Latest Accepted Articles

Factors influencing interfacial shear strength between UHPC and concrete substrate
XUE Shanbin, JING Fengjie, WANG Dan, ZHANG Peng, GAO Xiaojian
, Available online  
Abstract:
Ultra-high performance concrete (UHPC) has excellent mechanical and impermeability properties, and has a broad application prospect in the concrete structure reinforcement project. How to improve the bonding performance between UHPC and existing substrate has become an important topic of general concern in the field of civil engineering. In this paper, experimental studies were carried out using specimens prepared under standard curing conditions, and the effects of the water-binder ratio (w/b) of UHPC and the initial water saturation of the concrete substrate on the interfacial shear strength between them were first investigated. In addition, the evolution law of interfacial shear strength with age between the selected UHPC with a specific mix proportion and concrete with different saturation was investigated. Pre-wetted lightweight aggregate was incorporated into UHPC to achieve internal curing, and the evolution law of the interfacial shear strength between lightweight aggregate UHPC and concrete substrate after curing with different ages was investigated by taking into account the effects of the replacement rate of lightweight aggregate in UHPC, and the water saturation of concrete substrate. The microstructure of the interface between UHPC and concrete was observed using scanning electron microscopy. The results show that (1) for UHPC without lightweight aggregates, the interfacial shear strength between it and water-saturated substrate is the highest while the interfacial shear strength between it and dry substrate is the lowest irrespective of the change of the w/b of UHPC. The interfacial shear strength between UHPC and dry substrate decreases with the increase of w/b, and that between UHPC and pre-wetted substrate increases first and then decreases with the increase of the w/b. (2) The interfacial shear strengths between UHPC with a w/b of 0.154 and different saturated substrate all increase significantly at 28d compared to that at 7d. At 90d, only the interfacial shear strengths between it and 50% saturated substrate further increase significantly. (3) A low lightweight aggregate replacement rate can increase the interfacial shear strength between UHPC and dry substrate at 7d, while a high lightweight aggregate replacement rate can significantly increase the interfacial shear strength between UHPC and dry substrate at 28d and 90d. The interfacial shear strength between lightweight aggregate UHPC and 50% saturated substrate is significantly higher than that between lightweight aggregate UHPC and dry substrate at 28d and 90d. At 7d, a certain interfacial shear strength can be formed between UHPC with different lightweight replacement rates and water-saturated substrate, and the strength further increases at both 28d and 90d.
Preparation of high-strength MXene/PPy@BC composite films and their electromagnetic shielding properties
TANG Jie, LI Xiang
, Available online  
Abstract:
With the continuous development of communication technology and mobile electronic devices, electromagnetic interference problem is increasingly prominent, so the development of high performance electromagnetic shielding materials has become an important research direction. In this paper, a high conductivity MXene/polypyrrole (PPy)@bacterial cellulose (BC) film (MPB) with high conductivity was successfully prepared by a simple vacuum filtration method. The influence of different proportions of MXene and PPy@BC on the conductivity, mechanical properties and electromagnetic shielding performance of the composite film was deeply studied. The results show that when the ratio of MXene and PPy@BC is 3∶1, the conductivity and X-band electromagnetic shielding efficiency (EMI SE) reach the maximum, 1209 S/cm and 63.89 dB, respectively. In addition, due to the rich hydrogen bond interaction between PPy@BC and MXene, the maximum tensile strength of the composite film can reach 24.73 MPa, which is nearly 10 times higher than that of pure MXene film. The excellent comprehensive performance of MPB film shows its great potential in the EMI shielding of the next generation of intelligent and wearable electronic products.
Preparation of carbonxymethyl chitosan and its effects on medical dialysis paper
FU Bingqing, ZUO Jinhua, ZHANG Feiyang, XIONG Fangtao, YANG Jun, ZHAO Huifang, SHA Lizheng, CHEN Jianbin
, Available online  
Abstract:
In order to improve the water solubility of chitosan (CS) and extend its application in the field of papermaking, CS was used as the main raw material and chloroacetic acid was used as the etherification agent to prepare carboxymethyl chitosan (CMCS) under alkaline conditions. CMCS with different substitution sites were obtained by controlling the reaction temperature, time and pH value. Then, the structures of CMCS were analyzed by using infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (1H-NMR), and their degree of substitution and water solubility were measured. Finally, the prepared CMCS was used as additives to prepare dialysis paper, and the effects of CMCS dosage on the physical strength, permeability and antibacterial performance of dialysis paper were investigated. The results showed that the addition of CMCS with different substitution sites all improved the physical strength of dialysis paper, however, compared with the amino substituted CMCS (N-CMCS) and the amino and hydroxyl substituted CMCS (N,O-CMCS), the addition of the hydroxyl substituted CMCS (O-CMCS) had the most significant effects. When 2.5% O-CMCS was added to the papermaking pulp, the dry tensile, wet tensile and burst index of the paper were 61.6 N·m·g−1, 8.61 N·m·g−1 and 6.19 kPa·m2·g−1, which increased by 18.8%, 113%, and 91.0%, respectively. The air permeability of paper reached 7.98 µ m·(Pa·s) −1, meeting the requirements of air permeability of the dialysis paper. In addition, the paper containing O-CMCS, N-CMCS and N, O-CMCS all showed good antibacterial activity, and had antibacterial rates of 86.7%, 83.8%, and 83.6% against Escherichia coli, respectively.
Recent research progress of functional materials in industrial wastewater treatment
CHEN Hongyu, WANG Qinggang, HU Lin, SUN Hongjie
, Available online  
Abstract:
The continuous expansion of industrialization has led to a sharp rise in the rate of water pollution, the quality of water bodies is declining, while the human demand for freshwater resources is increasing day by day. In the face of the complex and severe water pollution situation, a variety of water treatment technologies are rapidly developing. Functional materials as the basis for the development of water treatment technology, more and more attention. Various types of functional materials have unique advantages, and have different processing roles and effects in water pollution treatment, but there are also different defects. The purpose of this paper is to summarize the effective treatment effect of several types of functional materials in the field of industrial wastewater, to describe the advantages and disadvantages of several types of functional materials, and to look forward to the possible future direction of research and exploration.
Progress in defect modulation of g-C3N4 based materials and its photocatalytic property
LU Yu, LIU Chengbao, ZHENG Leizhi, CHEN Feng, QIU Yongbin, MENG Xianrong, CHEN Zhigang
, Available online  
Abstract:
Semiconductor photocatalytic materials have become a key factor of photocatalytic technologies to solve environmental pollution and energy crisis. Among them, graphitic phase carbon nitride (g-C3N4) has shown great potential for application as an emerging highly efficient catalytic material. However, the unmodified g-C3N4 has disadvantages such as limited visible light response range, less reactive sites and high photogenerated carrier complexation rate, which severely limit its practical applications. Thus, researchers have adopted various strategies, such as designing and developing heterogeneous structures, defect engineering and morphological modulation to solve the problems mentioned above. Among them, defect modulation has attracted much attention because it can effectively modulate the electronic band structure of photocatalytic materials, delay carrier recombination and increase the surface reactive sites. This paper describes the types of defect modulations, defect modulation strategies, and finally summarizes the development and application of g-C3N4 based photocatalytic materials and gives an outlook.
Preparation and performance of smart high strength and high ductile concrete
LIU Jintao, HONG Yuchao, ZHOU Yu, WANG Weisheng, KONG Deyu
, Available online  
Abstract:
In this study, high strength and high ductility concrete (HSHDC) was developed by mixing carbon fiber (CF) and polyethylene fiber (PE). The mechanical properties and agility of HSHDC were analyzed. The results show that the compressive strength, flexural strength and tensile strain of HSHDC with 0.25vol% CF content were 7% higher than those of control group. The resistivity of HSHDC decreases significantly with the increase of CF content, and the resistivity of HSHDC with 1.0vol%CF content was as low as 10 Ω·m, which was three orders of magnitude lower than that of the control group. With different temperature and relatively humidity conditions, the resistivity of HSHDC mixed with CF showed good stability. Under cyclic loading, the resistivity change rate of HSHDC with 0.25vol%CF content showed a good correspondence with the stress, and the compressive stress and compressive strain sensitivity coefficients reached 0.75%/MPa and 136.5, respectively. For HSHDC with 0.25vol%CF content, the maximum resistivity change rate was 9.2% when the loading amplitude was 15MPa, and the peak resistivity change rate was 7.87% when the loading speed was 0.4 mm/min.
Strength characterization of 3 D hollow sandwich composite with Al-GF/PP faceplate under aerodynamic load
LIN Yanyan, GUO Xinghao, WU Can, LI Huaguan, XIANG Junxian, CHEN Xi, TAO Jie
, Available online  
Abstract:
With the increasing speed of high-speed trains, especially when passing through tunnels or meeting cars, aerodynamic loads place higher demands on the strength characteristics of the skin structure. 3D hollow sandwich composite with Al-GF/PP (Thermoplastic aluminum alloy-glass fibre/polypropylene) faceplate is a kind of sandwich material with fiber metal laminates as faceplate and 3D hollow composite as core material, which has the advantages of lightweight and high strength, sound and heat insulation, and can be used in the skin structure of high-speed train doors, skirts and so on. By comparing the performance of 3D hollow composites with different heights (10-25 mm) in flatwise compressive, edgewise compressive and flexural properties, it is found that the mechanical properties show a decreasing trend with the increase of the thickness, and the thicker 3D hollow composites have higher bending moments in the core and low structural stability. Aerodynamic load tests of 4 kPa, 5 kPa, 6 kPa and 7 kPa were carried out on the 3D hollow sandwich composite with Al-GF/PP faceplate. The results show that when the "8" fibres are subjected to forces perpendicular to the faceplate, the weft fibres carry the main load, which help to reduce the displacement of the fibres in the loading direction. The highest loading stress is applied at the joint between the core and the upper panel, and the main displacement occurs on the loaded side of the structure, with maximum displacement values of 1.80 μm, 2.26 μm, 2.72 μm, and 3.19 μm, respectively, and the aerodynamic loading of this order of magnitude does not lead to macroscopic deformation and failure of the specimens.
Microstructure and mechanical properties of Ni-rich TiNiZr alloy associated with repeated cold-rolling and annealing
ZHANG Jiang, HAO Gangling, QIAN Jiaxiang, YANG Yuanxia, WANG Xingfu, WANG Weiguo, WANG Dan, XU Qiaoping
, Available online  
Abstract:
TiNi shape memory alloys have clear target demand in a variety of fields owing to their excellent structural and functional properties. In this paper, focusing on B2 structural austenitic Ni-rich TiNi alloys, it is proposed to modulate the microstructure of the TiNi alloys through repeated cold rolling annealing, with an expectation to enhancing the lower mechanical strength and plastic deformation ability of the alloys. The dependence of the mechanical properties and microstructure of Ti48.9Ni50.9Zr0.2 and Ti47.9Ni51.9Zr0.2 alloys on cold rolling deformation and recrystallization annealing was systematically investigated. The tensile mechanical property tests showed that the repeated cold rolling annealing could significantly enhance the overall mechanical properties of the alloys, in which the tensile strength of Ti48.9Ni50.9Zr0.2 alloy is increased from 550 MPa in the unrolled samples to 1070 MPa after 6 passes of cold rolling annealing, and the elongation after fracture has grown from 4.9% to 10.0%. The EBSD, SEM and TEM microstructural observation reveals that the deformation and recrystallization structures of the alloy change alternately after multi-pass cold rolling and annealing, and the alloy grains are significantly refined and undergo an obvious preferred grain orientation. In addition, the basal texture of the alloy is further enhanced. The Ti2Ni and Ti3Ni4 precipitates were broken and refined during cold deformation, in which the nano-sized Ti3Ni4 precipitate exhibits a favorable matching with matrix. Furthermore, stress-induced martensite as well as a large number of high-density dislocations in the vicinity of the precipitation phases appeared in the alloy. The mechanical properties of alloys are strongly related to the microstructure, and the strengthening mechanisms can be understood by grain refinement strengthening, dislocation strengthening, precipitation strengthening and texture strengthening.
Current status of interface modification of carbon fiber cement-based composite materials
LI Zi Qi, PEI Chun, ZHU Ji Hua
, Available online  
Abstract:
Carbon fiber reinforced cement composite (CFRCC) is widely used in the fields of construction, infrastructure, and civil engineering due to its high strength-to-weight ratio, corrosion resistance, and durability. In the context of CFRCC, the interface plays a crucial role as it acts as a bridge connecting the matrix and the reinforcing phase. The performance and structure of the interface directly impact the bond strength of the composite material, thereby influencing its overall macroscopic properties. However, the inherent hydrophobic nature of carbon fibers and their inadequate bonding with aqueous suspensions limit their application in cement and other mineral building materials. To address this issue, researchers have explored physical and chemical modification methods to enhance the transfer of load from the mineral matrix to the carbon fibers. This paper provides an overview of the properties of carbon fibers, CFRCC, and CFRCC interfaces, while also summarizing recent studies by domestic and foreign scholars on CFRCC and its interface modification methods, such as oxidation, electrophoretic deposition, plasma, and grafting treatments, along with discussions on relevant mechanistic analyses. Additionally, it presents characterization methods for studying the properties of carbon fibers themselves and their bonding behavior with cementitious matrices.
Fabrication and properties of coaxial electrospun PLA/PEG composite nanofibers for thermal regulation
HU Baoji, CHEN Yirui, WANG Xu, PENG Yike, XU Feiyang, ZHANG Yifan, LIU Jiamin, ZHANG Qiaoling
, Available online  
Abstract:
To investigate the effect of spinning solvents on coaxial electrospun nanofibers and prepare thermal regulation nanofibers, polyethylene glycol (PEG) and polylactic acid (PLA) solutions were used as inner and outer layer spinning solutions respectively, and PLA/PEG nanofibers (NfC-S) were prepared by coaxial electrospinning. Three types of NfC-S were prepared using deionized water, Tetrahydrofuran (THF), and Dimethyl carbonate (DMC) /N, N-dimethylformamide (DMF) as inner solvents, named PPw, PPt, and PPd, respectively. The morphology, chemical structure, crystalline properties, mechanical properties, thermal properties, and hydrophilicity of NfC-S were studied, and the thermal regulation function was further investigated. The results showed that PPw obtained fibers with two different scales, and the average diameter increased by 190 nm compared to PPd. PPw exhibited higher elastic modulus and breaking stress, while PPd and PPt showed higher breaking strain, with the breaking stress of PPw increasing by 0.54 MPa compared to PPt. NfC-S possessed the melting endothermic capacity attributed to PEG, with PPt and PPw exhibiting significant temperature hysteresis during heating and cooling processes, demonstrating excellent thermal regulation capability. The hydrophobicity of NfC-S was lower compared to pure PLA (PP0), with the water contact angle of PPw (136.5°) being closest to PP0. In conclusion, thermal regulation NfC-S was developed based on the research for inner layer solvent, with PPw showing superior comprehensive performance, providing a reference for the controllable preparation of thermal regulation nanofibers.
Preparation of the porous ZIF-8 and the behaviors of loading ibuprofen
SUN Ruihua, YANG Zhuofan, ZHANG Ruibo, JIANG Qi, LU Xiaoying, LIAO Hai
, Available online  
Abstract:
Oral bioavailability of poorly soluble drugs is severely limited due to their low solubility. In recent years, metal-organic framework materials (MOFs) have attracted much attention because of their hydrophobicity and high specific surface area. In this paper, the porous ZIF-8, one of MOF family materials, were prepared by solution co-precipitation method. The specific surface area and pore size distribution of ZIF-8 were optimized by changing the molar ratio of Zn2+ to 2-Methylimidazole. In addition, ZIF-8 were used as the carrier for ibuprofen (IBP), a poorly soluble drug, and its loading performance was studied in detail. The results showed that when the molar ratio of Zn2+ to 2-methylimidazole was 1∶8, ZIF-8(8) had the largest specific surface area (1187 m2/g) and pore volume (1.183 cm3/g). And the loading capacity of ZIF-8(8) on IBP was as high as 21.8%. The drug carrier composite (IBP-ZIF-8(8)) showed a well dissolution rate in vitro, and its cumulative dissolution rate was about 98% in phosphate buffer solution with pH of 2.5 and 7.4. The survival rate of RAW246.7 cells treated with IBP-ZIF-8(8) was over 94%, demonstrating satisfied biosafety. ZIF-8(8) with excellent specific surface area, pore volume, good loaded-IBP performance and biosafety has great potential applications in drug controlled-release system.
Research progress on the recycling and reuse of waste polyvinyl butyral
WANG Mengdie, CHAI Liqin, ZHOU Lan, ZHOU Guoxuan, LIU Guojin
, Available online  
Abstract:
Polyvinyl butyral (PVB) resin has excellent film-forming properties, optical transparency, strong flexibility, elasticity, adhesion, and impact resistance. It is widely used in ceramic flower paper, coatings, adhesives, automotive windshield interlayer materials, solar cell packaging materials, and other fields. However, PVB exhibits non degradable characteristics, and the production of a large amount of waste PVB resin is prone to resource waste and environmental pollution. How to achieve the recovery and reuse of waste PVB resin is a research hotspot in the current engineering field. This article briefly introduces the characteristics of PVB resin and the sources of waste PVB resin, elaborates on the recycling technology of waste PVB resin, and provides examples of the application status of regenerated PVB resin in filtration materials, adsorption materials, toughening materials, foaming materials, and electrochemical materials. The review provides a reference for the recycling and reuse of waste PVB resin.
Research on dry friction and wear characteristics of SiC/AZ91D composites based on Archard wear mode
FU Hao, YAO Junping, LIANG Chaoqun, LI Buwei, CHEN Guoxin
, Available online  
Abstract:
The particle reinforced magnesium matrix composite is of great significance in the manufacture of piston. The service life of piston is closely related to the friction and wear properties of the material, so it can predict the wear resistance of magnesium matrix composite piston. Based on Archard wear model and adaptive mesh technology, a finite element model of SiC/AZ91D magnesium matrix composite and its matrix was established to explore its wear behavior under different loads, investigate its stress field distribution and wear depth, and conduct experimental verification to reveal the wear mechanism. The results show that, under different loads, the stress values of the nearest and furthest distance from the disc axis are larger on the contact surface of the disc pin, while other radial regions are smaller. With the increase of load, the stress values in all parts of the disc and pin contact area increase. Under different loads, the wear depth of the contact surface of the disc pin is smaller at the closest point to the disc axis, and the wear depth is larger and larger with the increase of the radial distance from the disc axis. With the increase of load, the wear depth increases in all parts of the disc and pin contact area. However, the wear depth of the composite is less than that of the matrix, which shows better wear resistance. Abrasive wear and peeling wear are the main wear mechanisms of the composite, adhesive wear is the main wear mechanism of the matrix alloy, and the simulation results are in good agreement with the experimental results.
Mechanical properties and toughening mechanism of polyurethane epoxy resin composite materials
MA Yanxuan, FU Shuangyang, WANG Shuaifei, WU Rui, GAO Yuhua, LI Meiyu, ZHANG Jian, ZHANG Peng, GAO Song
, Available online  
Abstract:
Epoxy resin materials have high brittleness and poor toughness, and are prone to aging, cracking, and peeling on the surface, making it difficult to protect concrete from complex working conditions such as marine environments. Polyurethane/Epoxy resin (PU/EP) composite materials with different systems were designed, and orthogonal experiments were conducted using the tensile strength, fracture elongation, and impact toughness of PU/EP composite materials as evaluation indicators. The optimal preparation formula for PU/EP composite materials was determined through response surface analysis method, with an R value of 1, a PU content of 15wt%, and a preparation temperature of 80℃. The results showed that the crosslinking effect of PU and EP was good, and the tensile strength, fracture elongation, and impact toughness of PU/EP composite materials were improved by 37.61%, 52.21%, and 47.07% compared to pure epoxy resin, respectively. With the increase of PU content, the proportion of flexible long chain segments in the material increases, and the area forming the secondary network increases. The coordination effect between molecules and the increase of soft connecting segments greatly improved the mechanical properties of the material, and the hardness and elastic modulus of PU/EP composite materials are reduced to a certain extent.
Multi-objective optimization of fiber orientation and grammage of recycled carbon fiber felt
LIU Rui, CHEN Hongda, HU Haixiao, LI Shuxin, WANG Jihui, CAO Dongfeng, ZHANG Yu, LI Ruiqi, WANG Hongrong, LU Lizhe
, Available online  
Abstract:
It is of great significance to realize the recycling and reuse of waste composite materials. Traditional recycling methods consume high energy and are easy to damage the material structure of the fibers. The recycled fibers are oriented in a disorderly manner and cannot be utilized for high value. In this research, the new recyclable epoxy resin developed by our team was used to manufacture type IV hydrogen storage vessel, and the efficient recycling method of carbon fiber from waste composite hydrogen cylinder was studied. The fiber wet orientation device was designed independently to prepare oriented fiber felt. The effects of various process in the wet orientation process on the quality of regenerated fiber felt samples, including orientation degree and weight, were explored. The response surface method (RSM) was used to establish the objective models related to the orientation and grammage of the fiber felt, and the reliability of the models were analyzed. Based on the models, the non-dominated sorting genetic algorithm Ⅱ (NSGA-Ⅱ) was used to perform multi-objective optimization of the parameters of fiber wet orientation process. The optimal solution was selected using technique for order preference by similarity to ideal solution (TOPSIS), and experiments were designed to verify the results of multi-objective optimization. The results show that the impact of various process conditions on the orientation of fiber felt is ranked as fiber length > fiber content > dispersant content > filter mesh hole size. And the order of the impact of various process conditions on the grammage of fiber felt is fiber content > dispersant content > filter mesh hole size > fiber length. The objective function models are very reliable for analyzing the orientation and grammage of the fiber felt. Through the multi-objective optimization algorithm, the optimal process parameters for the preparation of regenerated fiber felt are fiber length 3 mm, fiber content 6.37 g/L, dispersant content 13.37 g/L, and filter mesh hole size 0.75 mm. The orientation degree of the fiber felt prepared by verification experiment is 81.08%, with an error of 0.94% from the orientation degree(81.84%) predicted by genetic algorithm. The grammage of the fiber felt experimentally prepared is 42.86 g/m2, with an error of 0.68% from the grammage(42.57 g/m2) predicted by genetic algorithm.
Research progress on the application of lignin-based functional materials in barrier packaging paper
GAI Xiaoqian, LI Yu, LEI Tong, BIAN Huiyang, LU Hailong, XIAO Huining, LIU Chao
, Available online  
Abstract:
With the gradual depletion of petroleum resources, bio-based barrier packaging materials have garnered growing attention as an eco-friendly alternative to conventional petroleum-based plastic packaging. Lignin, the second most abundant natural polymer and the only renewable resource rich in repetitive benzene ring structural units, possesses biodegradability, biocompatibility and excellent processability. Currently, the majority of lignin is still disposed of through incineration as industrial by-products, resulting in limited utilization and low added value. Due to its unique chemical structure, water resistance, solvent resistance, aging resistance, and UV resistance, lignin exhibits significant potential in the development of bio-based barrier materials. However, further consideration is required regarding the structural characteristics of lignin, its multifaceted barrier properties in material applications, the establishment of structure-property relationships, and exploration of diverse application scenarios. Therefore, the present review provides a systematic and comprehensive review of the application of lignin-based functional materials in barrier packaging paper. Firstly, the structure and origin of lignin are briefly elucidated. A comprehensive overview of the current status of the application of lignin-based functional materials in barrier packaging papers is then provided, with particular emphasis on the advances in the use of lignin-based functional materials for water, gas, oil, ultraviolet radiation and flame retardancy properties in packaging paper. Finally, the primary challenges and future prospects for the development of lignin-based functional materials in barrier packaging paper applications are discussed. This review will provide a theoretical foundation for the utilization of lignin-based functional materials in the production of paper with single or multiple barrier properties, thereby providing practical significance for the industrial-scale manufacturing of value-added products derived from lignin.
Research progress in the preparation and application of functional materials based on inverse opal structure in water treatment fields
LI Jing, TANG Xinjun, HUANG Yong
, Available online  
Abstract:
The inverse opal structure (IO) is a typical spatial structure of photonic crystals. In addition to the interconnected, highly regular, and orderly homoporous structure, IO also has the properties of photonic crystals, including the slow light effect, multiple scattering effects, amplified photon absorption and emission characteristics. In recent years, applications for IO have included homoporous membranes, photonic inks, battery electrodes, sensors, etc. In this paper, we first briefly describe the construction strategy of IO, which is divided into the "three-step method" and "two-step method". Then, the research progress of IO in water treatment fields was summarized in detail, including filtration and screening, efficient adsorption, catalytic degradation, and water quality detection. Finally, the existing limitations and future development trends of IO materials in water treatment fields were elaborated and prospected.
Research Progress of Nano-enhanced Microcapsule Composite Phase Change Materials
WANG Cheng-jun, WANG Lin-qiang, WANG Rui-na, DUAN Zhi-ying, MENG Shu-juan, SHEN Tao, SU Qiong
, Available online  
Abstract:
Phase change materials (PCM) can bridge the gap between heat supply and demand in time and space, and are widely used in heat storage and thermal management systems. However, a single PCM has defects such as easy leakage, volume change, phase separation and corrosion. Therefore, microencapsulated PCM to prepare microencapsulated composite phase change materials (MEPCM) by microencapsulated technology and enhanced by different nano-fillers can not only effectively overcome the above defects, but also improve its thermal performance and operational stability. This paper first introduces the selection principle of the core material and shell of MEPCM, the composition and preparation strategy of MEPCM, focuses on the influence of nano-fillers of different dimensions on the thermal properties of MEPCM, and summarizes the application of MEPCM in the fields of construction, textiles and thermal management. The future research directions and challenges of nano-fillers in rational design and construction of high-performance MEPCM are also discussed.
Electric field driven micro 3D printing of high-precision circuit on bismaleimide resin matrix composite
LIU Yadong, ZHANG Houchao, ZHU Xiaoyang, XU Quan, LI Yirui, HAN Zhifeng, ZHAO Jiawei, LIU Qi, LAN Hongbo
, Available online  
Abstract:
Fiber-modified bismaleimide resin matrix composites are widely used in aerospace, smart skins, conformal antennas, electromagnetic shielding, high-frequency circuit substrates, and electrical heating by virtue of their excellent mechanical properties, high-temperature and corrosion-resistant characteristics. However, due to the non-flat, heterogeneous, and anisotropic characteristics of bismaleimide resin matrix composites, the simple, efficient, and low-cost fabrication of high-resolution circuits on this substrate is a current challenge to be solved. In this paper, a new method for fabricating high-precision circuits based on electric-field-driven micro-3D printing on quartz fiber modified bismaleimide resin matrix composites are proposed, and the basic forming principle and key technology implementation are described. Explored the characteristics of electric field distribution on the surface of non-flat heterogeneous composites and the changing law of field strength, and proposed a strategy to realize stable printing adjusting the threshold of electric field strength. The effects of the main process parameters on the precision, morphology and performance of the fabricated circuits were revealed experimentally, and the fabrication of various patterned circuits with a minimum line width of 50 μm had been realized by combining with an optimized process parameter. The typical sample manufactured had a conductivity of 4.5×107 S/m, and the resistance change rate was around 1% after 100 times of adhesion testing and 100 min ultrasonic experiments. It had excellent thermal response speed when applied to electric heating applications, and the maximum temperature can reach 158℃ under 3 V, and de-icing can be realized within 200s. This technology provides an effective method for the efficient and low-cost fabrication of fiber modified bismaleimide resin composite-based circuits, showing good prospects for industrial applications.
Recent progress in the preparation, properties and applications of superhydrophobic coatings
YANG Likai, WU Linsen, YANG Xu, MA Jiachen, NIE Yong, JIANG Xuchuan
, Available online  
Abstract:
Superhydrophobic coatings with excellent corrosion resistance, self-cleaning, anti-fog, drag reduction, or icing resistance have been paid more and more attention due to their applications in the engineering and coatings industry. In addition, the application of superhydrophobic coatings can be greatly expanded by introducing functional fillers such as heat insulation, anti-icing, flame retardant, and anti-corrosion into the coating. In this paper, the mechanism of superhydrophobic coating is first reviewed, and the classical wetting theory of superhydrophobic coating is further described, including Young's model, Wenzel model, and Cassie-Baxter model. The characteristics of different preparation methods of superhydrophobic coatings are compared, subsequently. Finally, the main problems existing in the development of superhydrophobic coatings are pointed out by introducing the research progress of multifunctional superhydrophobic coatings, and the development direction of superhydrophobic coatings is proposed.
Dynamic and static mechanical properties and energy dissipation of six polymer materials
XING Yongyang, WANG Haibo, WANG Mengxiang, LV Nao, CHENG Bing
, Available online  
Abstract:
In order to investigate the effect of different polymer materials as energy gathering tube tubes on energy gathering blasting, Uniaxial compressive experiments on different polymer materials under quasi-static conditions were conducted using an electro-hydraulic servo press and a 50 mm diameter Split-Hopkinson Pressure Bar. The static and dynamic mechanical properties, longitudinal wave velocity, energy dissipation and the deformation characteristics were studied. The results show that the maximum difference in wave impedance and quasi-static uniaxial compressive strength between different polymer materials reaches 42.5% and 312.3%, respectively. Under the impact load, the stress-strain curves of different polymer materials exhibit rebound phenomenon at the end of the curves, and the peak stress of PVC material is relatively higher among the six polymer materials under different impact pressures. From the analysis of energy transmission, dissipation rate and unit mass dissipation energy, PVC material has the highest energy transmittance among the six polymer materials, while energy dissipation and unit mass dissipation energy are the lowest. From the perspective of rock blasting, the absorption impedance ratio and incident energy are introduced for fitting analysis. The correlation coefficient between the fitting curves of PVC and PC materials is relatively high, which is more in line with the description of energy transfer during explosive explosion. Finally, based on all the analyses, it is believed that PVC material is the most suitable polymer material among the six types used in the experiment as a pipe material for energy gathering tubes.
Trajectory planning of in-situ fiber placement for carbon fiber composite shells
LIU Dong, TIAN Ming, WANG Fei, ZHANG Chengshuang, BAO Yanling, ZHANG Chenghao, SU Zhongmin
, Available online  
Abstract:
To address slippage issues at the end of a multi-function laying head, a prepreg tape laying trajectory planning method for robot placing carbon fiber composite material is proposed. First, laying angles and center angles are obtained based on a prepreg tape laying path model. A differential geometric solution is applied to transition from dynamic to static coordinates based on the center angle, enabling calculation of the paving pose. Second, the convergence speed and calculation accuracy are enhanced by refining the original Snake Optimization Algorithm and incorporating it into the inverse kinematics of the laying robot. Inverse kinematics is employed to obtain the joint angles of the front seven axes of the laying robot from the laying pose. Matching the joint angles to the center angles effectively suppresses slippage at the end of the placement head. Finally, simulations and experiments are conducted on in-situ molding of ellipsoid shell tow laying. The results demonstrate no occurrences of slippage or wrinkles during the in-situ molding experiment involving the laying out of tows for unequal pole hole shells. The laying pose accuracy reaches 10−16, meeting the precision requirements for in-situ molding pose of tow laying, thus making it suitable for practical applications in tow laying in-situ molding work.
Preparation and research of Diatomite@PNIPAm-stabilized Pickering emulsion with temperature responsiveness
WANG Chuanhao, WANG Mingye, LIU Ying, WANG Yongquan, SONG Yutong, ZHOU Chao
, Available online  
Abstract:
Aiming at the shortcomings of the emulsion stabilized by surfactant due to toxicity and non-environmental protection, modified diatomite particles (DE), the temperature-responsive Pickering emulsion was studied. Due to the advantages of superior biocompatibility, DE have application potential in the field of cosmetics and pharmaceuticals. First, the Diatomite@MPS was obtained by silane coupling agent (MPS) hydrophobic modified DE. Then, modified DE (Diatomite@PNIPAm) with temperature responsiveness was synthesized successfully by grafting the temperature-responsive polymer poly N-isopropylacrylamide (PNIPAm). According to the characterization results of FT-IR testing and water contact angle testing, the diatomaceous earth was modified successfully. The TGA results showed that the optimal molar ratio of the Diatomite@PNIPAm prepared from MPS to NIPAm was 1∶1. Subsequently, oil-in-water (O/W) Pickering emulsions were prepared with Diatomite@PNIPAm as an emulsifier at different concentrations, and 3.0 wt% was determined as the optimal concentration. In addition, the emulsion was prepared with different oil-water volume ratios from 1∶9 to 9∶1 after determining the Diatomite@PNIPAm concentration, and the results showed that the oil-water volume ratio was 7∶3 as the best. The characterization results of Differential scanning calorimeter (DSC) testing showed that the lower critical solution temperature (LCST) of the Pickering emulsion was 40℃. The emulsion can undergo at least 6 demulsification-reemulsification cycles, and possesses excellent demulsification-reemulsification cycle performance.
Effect of elevated temperature on failure behavior of hybrid bolted-bonded joints in composite structures
LU Yixian, CAO Dongfeng, HU Haixiao, CAI Wei, WANG Weilun, ZHENG Kaidong, JI Yundong, LI Shuxin
, Available online  
Abstract:
Experiments and simulations were conducted to investigate the load transfer mechanism and failure modes of a double-bolt single-lap hybrid bolted-bonded joint between GFRP plain weave laminates and an aluminum alloy plane under high-temperature conditions. The experimental aspect involved conducting tensile failure tests on hybrid bolted-bonded joints under high-temperature conditions of 80℃, and comparing them with three other working conditions: hybrid bolted-bonded joints at room temperature, high-temperature bolted joints, and room temperature bolted joints. Failure characteristics at macroscopic and microscopic scales of the hybrid jointed structure were characterized by means of 3D-DIC and SEM. The numerical simulation involved the development of a progressive damage failure model based on the LaRC failure criterion to accurately depict the evolution of in-plane failures. Additionally, cohesive elements were incorporated between plies to effectively simulate delamination behavior. The results indicate that the hybrid bolted-bonded joint exhibits an increase in ultimate load capacity compared to a bolt-ed joint at both room temperature and elevated temperature, with enhancements of 9.2% and 4.0%, respectively. However, it is noteworthy that the ultimate load capacity of the hybrid bolted-bonded joint specimens is reduced by 17.8% in the elevated temperature environment. The hybrid bolted-bonded joint mitigates stress concentration phenomena during the early stages of loading. However, noticeable stress concentrations occur on the surface under temperature-induced loading after premature adhesive failure. The ultimate failure modes include not only the static cross-sectional tensile failure observed in ambient conditions but also compression failure induced by bearing effects. In this scenario, the failure mode aligns with that of a pure bolted connection. The developed numerical simulation model can accurately predict the failure modes and evolution process of the structure, enabling a comprehensive analysis of the load transfer mechanism and failure patterns in hybrid bolted-bonded joint structures.
Degradation of bisphenol F by activated of peroxymonosulfate using sludge biochar loaded with cobalt iron bimetallic catalyst
ZHENG Mimi, YE Quanyun, HE Dechun, PAN Jie, LI Junfei, YANG Jianguo, MA Xiaorui, LIU Wangrong
, Available online  
Abstract:
In recent years, the large-scale construction of wastewater treatment plants has led to an increase in the production of sludge year after year, and the treatment of sludge is facing a serious challenge. Bisphenol F (BPF), which is widely used as a chemical additive in the industry, has been frequently detected in surface water, soil and sludge. By using municipal sludge loaded with cobalt-iron bimetal, cobalt-iron bimetallic@biochar composites (CoFeO@SBC) were prepared, and the catalytic performance was assessed by activating peroxymonosulfate (PMS) to degrade BPF. Scanning electron microscopy (SEM), specific surface area determination (BET), infrared spectroscopy (IR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterise and analyse the physicochemical properties of the prepared materials. The effects of the dosage of the materials, the dosage of the PMS, the initial pH, and the inorganic anions on the degradation of the BPF by the CoFeO@SBC/PMS system were investigated. The results showed that the pore structure of CoFeO was significantly improved after compounding with SBC, and the specific surface area was increased by 6.0 times. Moreover, CoFeO@SBC composites showed richer oxygen vacancies and —OH functional groups, which led to higher production of Fe(II) and Co(II). Therefore, CoFeO@SBC composites had excellent catalytic activity, which could almost completely degrade BPF (5 mg/L) within 10 min at the dosage of 0.04 g/L, and the degradation rate was 62% higher than that of CoFeO; Cl and NO3− showed less influence on the degradation effect of the system, while HCO3 had a significant inhibitory effect; EPR analysis shows that there are hydroxyl (·OH) and sulfate (\begin{document}$\mathrm{SO}_4 ^{\cdot-} $\end{document}) free radicals as well as singlet oxygen (1O2) and superoxide (\begin{document}$\mathrm{O}_2 ^{\cdot-} $\end{document}) free radicals in the CoFeO@SBC/PMS system. At the same time, the free radical quenching experiment, it is proved that \begin{document}$\mathrm{SO}_4 ^{\cdot-} $\end{document} is the key reactive oxygen species for the degradation of BPF in the system. Finally, the degradation products of BPF were identified by liquid chromatography-mass spectrometry (LC-MS), which could elucidate the primary degradation pathways and mechanisms in CoFeO@SBC/PMS system.
1D-3D cell coupling simulation of resin flow behavior in perforated sandwich composite materials
ZHOU Ziwei, NI Aiqing, FENG Yuwei, WANG Jihui
, Available online  
Abstract:
The Vacuum Assisted Resin Infusion process (VARI), recognized as a high-performance, cost-effective manufacturing technology, has been widely adopted in the production of large composite material components. Perforated core composite materials exhibit characteristics such as a high strength-to-weight ratio and strong load-bearing capacity. However, to accurately simulate the resin infusion process within perforated core composite materials, three-dimensional numerical calculations of resin flow within each hole of the core material are required, especially for thick components, involving substantial development costs and production cycles. To reduce the complexity and time costs of simulation calculations, this study proposed a novel 3D-1D finite element coupling method. Utilizing a self-developed ANSYS Fluent User-Defined Function (UDF) subroutine to simulate resin flow within the core material holes, the need for physical modeling of a large number of holes is avoided. This approach successfully optimizes the model construction and simulation calculation process of the vacuum infusion process for perforated core composite materials. The feasibility of the simulation was validated through full-scale infusion experiments. The research results indicate that the numerical simulation closely aligns with experimentally measured infusion time, providing a relatively accurate representation of resin flow during the formation process of perforated core structures.
Decoupling cohesion method based on mode I delamination damage mechanism of composite materials
ZHANG Xudong, DUAN Qingfeng, CAO Dongfeng, CHEN Chongyi, HU Haixiao, WANG Jijun, LI Shuxin
, Available online  
Abstract:
Delamination damage is one of the primary damage modes in aerospace composite structures. Mode I delamination exhibits characteristics of low initial fracture toughness and complex damage patterns. Analyzing the interrelationships among three damage mechanisms at the crack tip region and bridging fiber damage evolution plays a crucial role in studying Mode I delamination. This paper specifically designs T700 level carbon fiber/epoxy composite laminates with three different interlayer configurations (0//0, 0//45, 0//90) and conducts Mode I delamination tests. By observing the initiation and evolution of delamination, summarizing DCB experimental results in load-displacement curves and R-curves, and employing various characterization methods like SEM analysis based on specimen fracture surfaces, it reveals the damage mechanisms at the crack tip. Subsequently, a new approach to decoupling layered damage mechanisms is proposed, based on three bilinear cohesive constitutive laws. This method establishes a cohesive element model to decouple layered damage mechanisms at different damage scales, independently characterizing the contributions of different damage mechanisms during layered propagation. Parameters required for simulation are obtained from experiments, and the simulated results exhibit good consistency with experimental data.
Dynamic mechanical properties of novel star-rhombic negative Poisson's ratio honeycomb structure
LI Na, LIU Shuzun, ZHANG Xinchun, ZHANG Yingjie, QI Wenrui
, Available online  
Abstract:
In order to further improve the crushing resistance and energy-absorbing capacity of the honeycomb structure, by periodically arraying typical star-shaped and star-rhombic cells, the reentrant star-shaped honeycomb structures (RSH) and the novel in-plane enhanced star-rhombic honeycomb structures (ESH) were constructed in this paper. The in-plane mechanical response and energy absorption characteristics of ESH under different loading directions were systematically investigated through experiments and finite element (FE) simulations. Compared with RSH, the negative Poisson's ratio characteristics of ESH under quasi-static compression are weakened, but the energy-absorbing capacities are significantly improved. In addition, by combining the deformation features of micro-topological cells, the deformation mechanism that the stress-strain response of ESH-y exhibits a double-plateau characteristic at low velocities of crushing is revealed, and the influence of the structural parameters α, t, and b on the plateau stresses is discussed. Based on the periodic layer-by-layer collapse deformation features of ESH under high-velocity crushing and the momentum theorem, the theoretical solutions of the high-velocity plateau stress in different loading directions are obtained, and theoretical results are in good agreement with FE results. This study can provide a reference for the innovative design of novel negative Poisson's ratio structures with better mechanical properties.
Preparation of CQDs-rGO/ZnO composites and photocatalytic degradation of metronidazole
YE Hongyong, YANG Yanju, WANG Minghui, ZUO Guangling, DU Jia
, Available online  
Abstract:
The low visible light activity, low photogenerated carrier mobility and easy recombination of ZnO limit its practical application in the field of photocatalysis. To overcome these limitations, a carbon quantum dots (CQDs)-reduced graphene oxide (rGO)/ZnO ternary composite catalyst was prepared by an ultrasonic-assisted impregnation method and characterized for its crystal structure, morphology, and photoelectric properties using XRD, SEM, TEM, XEDS, XPS, BET, UV-Vis DRS, VB-XPS, PL, TPR, and EIS. The photocatalytic activity of CQDs-rGO/ZnO composite catalyst was investigated with simulated antibiotic wastewater metronidazole (MTZ) as degradation object. The results show that the introduction of rGO and CQDs can optimize the band structure of ZnO and enhance its absorption of visible light. The strong electrical conductivity of rGO and CQDs can promote the rapid transfer and separation of photogenerated carriers, and effectively improve the photocatalytic activity of CQDs-rGO/ZnO composite catalysts. The quenching experiments show that hydroxyl radical (·OH) and superoxide radical (·O2-) are the main active substances in the reaction process. When the recombination amount of CQDs is 1 wt%, the photocatalytic activity of CQDs-rGO/ZnO is the best, and the degradation rate of MTZ can reach 87.8% under visible light irradiation for 2.5 h. After four cycles, 75.2% of MTZ can still be degraded, indicating that the physicochemical properties of the CQDs-rGO/ZnO composite catalyst are stable.
Experimental study on axial compressive damage performance of CFRP-reinforced wood columns
HUANG Junjie, SHE Yanhua, ZHANG Hefan, HE Jiaming
, Available online  
Abstract:
To study the axial compression damage performance and failure mechanism of wood columns strengthened with carbon fiber reinforced polymer (CFRP), axial compression tests and real-time acoustic emission (AE) monitoring were carried out on six groups of wood columns with different CFRP winding methods. The effects of different winding layers and winding angle on the damage forms, mechanical properties, energy absorption properties and acoustic emission parameters of CFRP-reinforced wood columns were analyzed. The results show that: the reinforcement of CFRP can significantly improve the mechanical properties of wood, inhibit the occurrence of brittle damage; with the increase of the winding layers and angle, the ultimate bearing capacity of the wood columns increases from 112.63 kN to 161.21 kN, and the displacement ductility factor also increases from 1.44 to 1.72; the increase of CFRP winding layers and angle can significantly improve the stability and energy absorption capacity of CFRP-reinforced wood columns in the axial compression damage process; according to the evolution characteristics of acoustic emission ringing count, the damage process of CFRP-reinforced wood columns can be divided into three stages: elastic stage, compressive yield stage and damage failure stage; with the increase of the winding layers and angle, the peak frequency of acoustic emission gradually transitions from the low-frequency range (0~80 kHz) to the high-frequency range (160~240 kHz), and the damage form changes from large-scale damage to small-scale damage; the probability density of acoustic emission energy of wood columns with different winding methods follows a power-law scale-free distribution, the critical indices under six reinforcement methods are 1.31, 1.33, 1.36, 1.43, 1.49 and 1.57, respectively; the critical index increases with the increase of winding layers and angles, the reinforcement of CFRP limits the development of internal cracks and weakens the deterioration of the internal structure of the wood.
Glucose Sensor Based On Co-MOFs-modified Commercial Strip Electrodes
XIA Haiyan, Li Jianan, XU Jianghong, ZHANG Rao, QUAN Changyun, LI Suyuan
, Available online  
Abstract:
The oxidase catalyst in glucose sensors can be easily affected by temperature, humidity, PH. As a result, developing some catalysts with low cost and high sensitivity has a broad application prospect. Metal-organic Frameworks (MOFs) have attracted much attention because of their high mass transfer rate, adjustable porosity and strong electron transfer ability. The screen-printing technique has been used to fabricate commercial electrodes due to its low cost and batch preparation. Here, Co-MOFs were successfully synthesized by a simple and economical method at room temperature and coated on commercial strip silver-carbon electrode by screen-printing technique. As a biosensor catalyst, Co-MOFs nanomaterials exhibit high electrocatalytic activity for glucose. The results showed that the sensitivity of Co-MOFs-based strip electrode for glucose detection was 1393 nA·L/(mmol·cm2). The detection limit was 0.58 μmol/L (S/N = 3) and the linear range was 0.1-0.5 mmol/L. This work has certain guiding significance for the design of multi-function electrode in glucose sensor.
Deformation energy absorption characteristics and structure gradient design of novel cosine function-based lattice materials
LV Ruoxuan, REN Haoqian, MEI Xuan, NIU Xinxiang, CAO Xi’ao, WANG Zhen, ZHU Guohua
, Available online  
Abstract:
This study proposes a new type of cosine function cell-based (CFCB) lattice materials and conducts experimental and simulation studies on the mechanical properties of such materials under quasi-static out-of-plane compressive load. The experimental results show that the energy absorption of the CFCB lattice material is improved by 134.4% compared with that of the body centered cubic (BCC) lattice material. Besides, Through numerical simulation, it is found that the energy absorption of CFCB lattice materials increases with the increase of the diameter of the single-cell diameter. In order to further improve the out-of-plane compression deformation mode and improve the bearing performance of uniform CFCB lattice materials, an interlayer gradient CFCB lattice material was designed, and energy absorption capacity of these gradient lattice materials and their key affecting factors are experimentally and numerically investigated. The results show that the gradient CFCB lattice materials have superior advantages in energy absorption compared with uniform CFCB lattice materials, and it is also found that increasing gradient coefficients can improve their load-bearing capacity and energy absorption capacity. Finally, the multi-objective discrete optimization method was used to optimize the design of the interlayer gradient CFCB lattice material, and the mass of the optimized gradient CFCB gradient lattice material was reduced by 20.9%, and the energy absorption was increased by 7.1%. This study can provide reliable experimental results, accurate numerical models and efficient optimization methods for the design of novel CFCB lattice materials and their gradient configurations.
Numerical simulation and theoretical analysis of flexural strengthening of RC beams with high-strength steel strand mesh/ECC
LI Ke, WANG Shaohua, ZHENG Shuning, FAN Jiajun, ZHU Juntao
, Available online  
Abstract:
Using a combination of finite element simulation and experimentation, the impact of reinforcement layer material quantity, properties of reinforcement materials, and characteristic parameters of RC (Reinforced Concrete) beams on the flexural performance of RC beams strengthened with high-strength steel wire mesh/ECC (Engineered Cementitious Composites) was investigated. Firstly, the finite element (FE) analysis model of existing nondestructive RC beams strengthened with high-strength steel wire mesh/ECC was established, and its effectiveness and accuracy were verified by comparing with the experimental results. The validated FE model was adopted to analyze the influencing factors of flexural performance of strengthened beams systematically. The results indicate that the strengthening method can significantly enhance the flexural bearing capacity, stiffness, and ductility of RC beams, with improvement ranges of 7.81% to 61.84%, 6.35% to 40.90%, and 5.92% to 50.16% respectively. With the increase of longitudinal steel strand reinforcement ratio, thickness and cracking stress of ECC, the promotion range of bearing capacity increases, while the increase of longitudinal steel reinforcement ratio and section height of RC beams decrease the increment of bearing capacity. The increase of the thickness of ECC and the reinforcement ratio of longitudinal steel strand increase the promotion range of stiffness, but the promotion range decreases with the increment of longitudinal reinforcement ratio, concrete strength and section height of RC beams. The increment of ductility only increases with the increase of concrete strength. On this basis, combined with relevant mechanical theories, the calculation formula for the limit amount of steel strands for flexural strengthening and simplified calculation formulas for the normal-section bearing capacity of RC beams reinforced by high-strength steel wire strand mesh-reinforced ECC are proposed, calculation results are in good agreement with experimental and numerical simulation results.
Classification, absorbing mechanism and research progress of biomass-derived carbon-based composite absorbing materials
WU Zhihong, REN Anwen, LIU Yijun, XUE Qunhu, NIU Dan, CHANG Jijin
, Available online  
Abstract:
In order to solve the electromagnetic wave pollution caused by electronic information technology, carbon-based composite absorbing materials have received extensive attention. Biomass-derived carbon composites not only have excellent electromagnetic wave absorption ability, but also have the advantages of low density, wide source and low cost. Firstly, the preparation method and process of biomass derived carbon are described. Secondly, the structural and morphological characteristics of three kinds of biomass-derived carbon, including plant kingdom, fungus kingdom and protista kingdom, were systematically summarized, and the research results of biomass-derived carbon-based composite absorbing materials in recent years were summarized. Then, the structural morphology and electromagnetic wave absorption properties of different kinds of absorbing materials are compared, and the absorbing mechanism of various materials is analyzed. Finally, the current wave absorbing properties and disadvantages of biomass-derived carbon matrix composites are analyzed, and the future development direction is prospected. This paper provides comprehensive induction, classification, analysis and theoretical support for promoting the research of non-animal biomass derived carbon composite absorbing materials, and provides ideas for its future development.
In-plane tensile property of deformable honeycomb structure with compliant hinge
ZHAO Chang, ZHOU Li, QIU Tao
, Available online  
Abstract:
A deformable honeycomb structure with compliant hinge which is composed of the cross-shaped honeycomb and the half inside Lamina Emergent Torsional joint was proposed. By reducing the in-plane stiffness, the deformation ability of the structure is improved, and it has the characteristics of light weight and low in-plane modulus. The in-plane equivalent elastic modulus of the deformable honeycomb structure was studied by theoretical analysis, and simulation and experimental verification were carried out. The influence of geometric parameters on the equivalent elastic modulus of the structure was also analyzed. The in-plane deformation ability of the deformable honeycomb with compliant hinge and the cross-shaped honeycomb were compared through simulation and experiment. The results show that the deformable honeycomb structure with compliant hinge has better in-plane deformable ability. Compared with cross-shaped honeycomb, the equivalent elastic modulus of deformable honeycomb with compliant hinge is reduced by more than 80%. Thus, the combination of compliant hinge and deformable honeycomb structure is an effective way to improve the in-plane deformation ability of honeycomb structure.
Analysis of early microscopic pore structure of electrolytic manganese residue modified polymer magnesium phosphate cement composites
YANG Tianxia, QIAO Hongxia, LUAN Shuai, LU Chenggong, ZHANG Lei
, Available online  
Abstract:
Electrolytic manganese residue (EMR) can slow down the hydration rate of polymer magnesium phosphate cement composite mortar, prolong the setting time and improve the microstructure. Through macroscopic physical and mechanical properties, working performance, combined with microscopic means such as X-ray diffraction (XRD), scanning electron microscopy (SEM) simultaneous thermal analysis (TG-DTG) and low field nuclear magnetic resonance (NMR) techniques were used to investigate the mechanism of the influence of EMR dosage on the early macroscopic and microscopic pore structure properties of magnesium phosphate cement. The results show that the addition of EMR can improve the working performance of the slurry, enhance the later strength and effectively refine the pore structure; The 28 d compressive strength value of adding 2% EMR reaches 49.5 MPa, and the strength of 3% and 4% additives is significantly reduced; In addition to the elongated tree like struvite (MgKPO4·6H2O) and block like MgO in the raw material, Mn elements participate in the reaction to form manganese containing compounds, and the hydration products overlap with each other to form a dense microstructure which refines the pores; TG-DTG curve at 100 ℃ appeared obvious heat-absorption peak corresponds to the heat-absorption dehydration phenomenon of guano stone, the mass loss rate is 13.299%; EMR-doped specimens appeared three heat-absorption peaks, including the process of the loss of bound water by Mn(OH)2 and Mn3(PO4)·6H2O; T2 spectra relaxation time will be lagging behind, the pore size in the range of the transition pores and the distribution of the capillary pores. The total porosity decreases with the increase of doping, and the permeability decreases first and then increases. The pores of composites with 1% and 2% doping are mainly distributed by gel pores and transition pores, the distribution area of macropores is less, the internal structure is more dense, and the permeability is low, the saturation of bound fluid is high, and the saturation of free fluid is low.
Microstructure and Wide-temperature Range Tribological Properties of Silicide Coatings on High Niobium TiAl Alloy
LI Yongquan, HAO Qingrui, WANG Cunxi, LIU Guangjun, GAO Yang, LI Xuan
, Available online  
Abstract:
In order to improve the deficient oxidation and wear resistance of TiAlNb intermetallics, a dual rare-earth modified silicide coating was prepared on a TiAlNb9 alloy using the pack cementation process. The microstructure and phase composition of the coating were analyzed and characterized, and the friction and wear behavior of the TiAlNb9 substrate and the Si-Ce-Y co-diffused coating against WC balls has been comparatively investigated across a broad temperature range. The results show that the coatings prepared with different activators, including NaF, NH4Cl, and AlCl3·6H2O, have multi-layer structures: from the surface to the interior, the coatings are composed of outer layers of (Ti,Nb)Si2, (Ti,Nb)5Si4 and (Ti,Nb)5Si3, middle layers of (Ti,Nb)5Si4 and (Ti,Nb)5Si3, and the inner layers of TiAl2. The activators have imposed a significant impact on the density of the co-diffusion coatings. Under experimental conditions, the friction and wear resistance of the Si-Ce-Y co-diffusion coating are significantly better than those of the TiAlNb9 substrate. The wear mechanisms of the TiAlNb9 substrate at 20℃ are abrasive wear and plowing wear, while at 600℃, the main wear mechanisms are oxidational wear, plowing wear, and abrasive wear. The wear mechanisms of the Si-Ce-Y co-diffusion layer at 20℃ and 600℃ are similar, mainly including delamination wear and abrasive wear.
Interface thermal stability and element diffusion law of SiCf/TC18 composites
CHEN Weilong, ZHANG Yuming, YANG Qing, YAO Hongrui, WANG Yumin
, Available online  
Abstract:
Interfacial reaction will have a significant impact on the mechanical properties of titanium matrix composites. In order to determine the diffusion of elements and the growth law of interfacial reaction layer of SiCf/TC18 composites, SiCf/TC18 composites were prepared using magnetron sputtering precursor wire method and hot isostatic pressing process. Heat exposure experiments were conducted at different temperatures (400, 600, 800 ℃) and times (50, 100, 150, 200 h) to analyze the changes in interfacial reaction layer thickness, element distribution, and diffusion patterns of SiCf/TC18 composites in hot isostatic pressing and hot exposure states. More importantly, this work elucidated the mechanism of element mutual diffusion, summarized the growth law of interface reaction layer thickness with heat exposure time, and revealed that the interface reaction layer products of SiCf/TC18 composites are mainly TiC. After calculation, the interface index factor of SiCf/TC18 composites was 4.0 × 10−6 m/s1/2, the activation energy of reaction layer growth was 80.31 kJ/mol, the material exhibited excellent interfacial thermal stability at below 400 ℃.
Mica nanosheets splitting of aramid fiber and enhanced mechanical and insulation performances of the composites nanofilms
LI Nan, LU Zhaoqing, WANG Yang, NING Doudou, YAN Ning, HUA Li, E Songfeng
, Available online  
Abstract:
The mica nanosheets (MNSs) were prepared by high-speed mechanical ball milling as the reinforcement, and introduced into the splitting process of aramid fibers. The aramid nanofibers (ANFs) were prepared in a dimethyl sulfoxide/potassium hydroxide (DMSO/KOH) system. ANF/MNS composite films were prepared by vacuum-assisted filtration, and the effect of MNS content on the mechanical properties of ANF films was investigated. It gains the best mechanical properties and insulation properties when the MNS content is 0.041 wt.%. The tensile strength is 249.3MPa, the toughness is 36.7 MJ·m−3, and the dielectric breakdown strength is 46.2 kV·mm−1. They increased by 45.1%, 197.1%, and 60.0% compared with the pure ANF films, respectively. Nanoscale MNS can form strong interfacial interaction with ANF, and the inherent strength of MNS also contributes to the improvement of the mechanical properties of nanofilms.
Research progress on machining process of embedded holes in hot-section ceramic-matrix composite components
LUO Xiao, LIU Xiaochong, ZENG Yuqi, LI Jian, XU Youliang, LI Longbiao
, Available online  
Abstract:
Ceramic-matrix composites (CMCs) are typical difficult-to-machine materials, which possess great hardness—second only to diamond and cubic boron nitride—and anisotropy. The fundamental structure of CMCs parts in aeroengines is the embedded holes (air film holes, etc.) in the hot-section components. These holes are crucial for the preparation and molding of CMCs components as well as the service life. The categorization of embedded holes in hot-section CMCs components is given in this paper. The processing principles, process characteristics, selection of process parameters, characteristics of the processing defects and formation mechanism, etc., are all determined by analyzing the methods used for processing CMCs embedded holes, including conventional mechanical processing methods, ultrasonic vibration-assisted processing methods, laser processing methods, etc. Recommendations for the processing of CMCs embedded holes with different diameters and depth-to-diameter ratios are also provided.
Effect of warp yarn paths on bending properties of 3D woven composites
ZHAO Shibo, CHEN Li, GAO Ziyue, WANG Jingjing
, Available online  
Abstract:
Three types of 3D woven composites (3DWC) with different warp paths were designed. Using a combination of experimental research, finite element analysis and SEM morphology analysis, the bending properties, damage mechanism and fracture morphology of 3DWC were studied. The results show that the warp paths have a significant effect on the bending properties of 3DWC. Compared to the stuffer plain woven composites (SPWC), with the increase of the warp yarns float length, the stuffer twill and stuffer stain woven composites (STWC and SSWC) bending strength increase by 54.64% and 127.61%, and the modulus increase by 44.11% and 47.11%, respectively. The failure modes of the SPWC are the fracture of the stuffer and the warp yarns, while the fracture modes of the STWC and SSWC are mainly yarns fracture and interface debonding. The stuffer yarns play the main role under the process of bending load, while the difference of warp yarn paths leads to the change of stress transfer, crack propagation, bending property and failure mode of three 3DWC.
Effect of freeze-thaw cycle aging on properties of bamboo fiber/polypropylene composites
LI Zhenyu, LI Xingong
, Available online  
Abstract:
Bamboo fiber/polypropylene (BF/PP) composites are often used in the field of outdoor municipal engineering. In high latitude areas, the alternating effect of cold, heat, humidity, and freezing will seriously deteriorate the properties of the materials. In explore the aging resistance of BF/PP composites in high latitudes, BF/PP composites were prepared by synergistic modification of compatibilizer and coupling agent. After freeze-thaw cycle aging treatment, the physical and mechanical properties and apparent properties of the materials were studied. The creep behavior of the material was studied by 5400 s short-term creep test method, and the micro morphology and chemical compositions of the materials were analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy. The results show that after 720 h freeze-thaw cycle aging, the retention rates of tensile strength, flexural strength, flexural elastic modulus, and notched impact strength of BF/PP composites are 76.90%, 86.89%, 82.81% and 71.83%, respectively. Deep cross cracks, holes, and faults formed in the BF/PP composite, and the surface hydrophobicity of the BF/PP composite decreased, and obvious color changes occurred. The 5400 s short-term creep behavior of BF/PP composites was further fitted by Burgers model, and the influence mechanism of freeze-thaw cycle aging on the creep resistance of BF/PP composites was explored.
Ultra-wide range composite flexible pressure sensor based on air layer structure and carbon nanotube modified dielectric layer
MA Wenjun, ZHANG Jie, LI Changjiang, ZHU Liyang, HE Li, CHEN Xiaoming
, Available online  
Abstract:
A wide detecting range and high sensitivity are crucial factors to fabricate the flexible pressure sensors with high resolution and precision across various application scenarios. Despite the exploration of numerous microstructures and composite material mediums to enhance the sensitivity of pressure sensors, the detection range has remained narrow, because of the constraint between wide detection range and high sensitivity. In this study, a capacitive flexible pressure sensor with ultra-wide detecting range have been developed, where a multi-walled carbon nanotubes (MWCNTs) reinforced poly(vinylidene fluoride-co-trifluoroethylene) P(VDF-TrFE) composite was used as the dielectric layer. At same time, to enhance the sensitivity, an air layer was introduced between dielectric layer and packager layers. Consequently, the detected range as-fabricated sensor could reach to 0.1 – 10 MPa, which was wider than those of the reported flexible sensors. Additionally, it exhibits a high sensitivity (1.673 MPa−1 and 0.302 MPa−1) and excellent linearity in the ranges of 0.1 - 0.5 MPa and 0.5 - 10 MPa, respectively. Furthermore, an online monitoring system for capacitive pressure sensor stress was designed, of which the accuracy reached up to 95.0 %. Based on these results, the designed sensor and detecting system exhibited the potential applications flexible electronic devices and miniature pressure monitoring devices.
Thermal and mechanical properties of polyethylene glycol modified lignin/polylactic acid biocomposites for 3D printing
JU Zehui, WANG Zhiqiang, ZHANG Haiyang, ZHENG Wei, SHU Biqing
, Available online  
Abstract:
Polylactic acid (PLA) was a green, renewable and degradable polymer material, which was considered to be the most commercially available material at present. However, the rigidity of the main chain structure of PLA material determined its weak impact strength and low elongation at break, which limited its application in a wide range of fields. In this study, a twin-screw extrusion method for preparing PLA and polyethylene glycol (PEG) modified lignin biocomposites was proposed, in order to improve the mechanical properties of 3D printed lignin / PLA composites and expand the application field. The structure of PEG modified lignin was studied. The effects of soda lignin and PEG modified lignin on the physical and mechanical properties, microstructure, thermal properties and degradation properties of PLA composites were studied. The experimental results showed that PEG can be grafted onto lignin and the thermal properties of lignin can be improved. The addition of PEG modified lignin increased the heat resistance of PLA composites. With the addition of 30% PEG modified lignin, the tensile properties of the composites did not decrease significantly. Compared with L30/PLA, the tensile stress and elongation at break of PL30/PLA were increased by 18.1% and 81.9%, respectively. Compared with pure PLA, the composite has a better degradation rate in water systems, especially in alkaline media. Therefore, PEG modified lignin not only improved the added value of lignin, but also provided a new way for the production of high-performance PLA composites.
Preparation and Properties of thin-wall flame-retardant polycarbonate materials with low heat release and smoke
JIANG Hui, LIU Jie, ZHANG Lu, LI Sanxi, TANG Tao, WANG Song
, Available online  
Abstract:
The preparation of halogen-free and fluorine-free thin-wall flame-retardant polycarbonate (PC) with low smoke and heat release was a challenge in the field. Polyborosiloxane (PBS) flame retardant wasprepared by polycondensation reaction between octamethyl cyclotetrasiloxane and boric acid, and then compounded with boron-phenolic resin (LPR) to prepare PBS-LPR/PC composites. The results show that whenthe total amount of PBS and LPR is 10 wt% and the mass ratio is 3∶1, the best flame-retardant effect is shown in PC, the 1.6 mm thick PC sample can pass UL-94 V-0 rating. Compared with that of pure PC, the peak heat release rate (pHRR), the peak smoke production rate (pSPR), the total heat release (THR)and the total smoke production (TSP) of sample reduces by 76%, 64%, 49% and 65%, respectively. The investigation on flame-retardant mechanism show that LPR decrease the viscosity of PCcomposites first and then increase, which confirms the generation of cross-linking reaction. The notched ipact strength of 7.5%PBS-2.5%LPR/PC is 2.3 times that of PC, which makes the material show high toughness.
Research progress on testing methods, influencing factors and applications of graphene thermal conductivity
ZHANG Zhiyuan, BAI Jia-qi, RAO Changlv, WEI Yuxue, CHEN Jingshuai, WU Mingyuan, CHENG Qin, CAI Mengdie, SUN Song
, Available online  
Abstract:
Graphene has attracted much attention due to its unique structure and excellent thermal conductivity, which is widely used in energy materials, battery materials, thermal composite materials fields as a two-dimensional material with high thermal conductivity. It is of great significance to deepen the understanding of solid-state heat transfer mechanisms by theoretical and experimental research on the thermal conductivity of graphene, and it can guide the design of the development of energy technology, thermal management and heat dissipation technology of electronic devices and the high-efficiency thermal conductivity materials. In recent years, there are numerous reports on the thermal conductivity of graphene, and it is beneficial for researchers to carry out their work more effectively by summarizing these reports on the thermal conductivity of graphene. This work summarizes the testing methods, influencing factors, and application status of the thermal conductivity of graphene. Firstly, the thermal conductivity measurement methods of single-layer, few-layer and multilayer graphene and graphene matrix composites are introduced, including Raman spectroscopy, thermal bridge, laser flash and 3ω method. Then, the theoretical research achievements on the thermal conductivity of graphene was summarized and the influence factors of the intrinsic thermal conductivity of graphene such as size, number of layers and defects were discussed. Next, the application of graphene as a thermal conductor in energy materials, battery materials and modified composite materials is summarized. Finally, the research on graphene’s thermal conductivity is concluded and the current challenges and issues was highlighted in graphene’s thermal conductivity research. Moreover, the prospect for future development direction is proposed.
Interface characteristics and mechanical properties of reactive melt infiltrated C/C-SiC-ZrC matrix composites
DING Jiaxin, CHEN Zhaoke, WANG Duo, XIONG Xiang
, Available online  
Abstract:
C/C-ZrC-SiC matrix composites are widely used in aerospace field as a kind of promising thermal protection materials. But C/C-ZrC-SiC matrix composites prepared by reactive melt infiltration (RMI) have the disadvantage of low mechanical properties, which is the main factor restricting its development and application. In order to improve the fiber damage and mechanical properties of the C/C- SiC-ZrC matrix composites, 300 nm pyrolysis carbon(PyC) interface, 300 nm PyC/SiC double-layer interface, and 100 nm, 300 nm, and 800 nm (PyC+SiC) co-deposited interfaces were introduced into carbon fiber needled preform by chemical vapor deposition(CVD); and then the C/C-SiC-ZrC matrix composites were prepared by RMI. The phase composition, micro-morphology, element distribution and interface damage were investigated by XRD, SEM, EPMA and TEM, and the mechanical properties of the composites after RMI were evaluated by three-point bending tests. The results show that the introduction of the interfaces not only protect the fibers, but also improve the bonding state between the fibers and the matrix, which greatly avoids the erosion of the carbon fibers by RMI. The PyC interface provided limited protection to the fibers, while the PyC/SiC double-layer interface provided the best protection. The interface type and interface thickness have an important effect on the mechanical properties of the composites. When the interface thickness is the same, the flexural strength of the composites with (PyC+SiC) co-deposited interface and the composites with PyC/SiC double-layer interface are 162.80 MPa and 208.58 MPa, respectively, which are superior to those of the composites containing the PyC interface; the mechanical properties of the composites show a first increase in the thickness of the interface with the increase in the thickness of the interface with the increase in the thickness of the interface. With the increase of (PyC+SiC) co-deposited interface thickness, the mechanical properties of the composites show the trend of increasing and then decreasing.
Sizes effect on the tensile behaviors of H65-IF-H65 laminated metal composites
WANG Kun, AN Junbo, FEI Ruoyu
, Available online  
Abstract:
The H65-IF-H65 laminated metal composites (LMCs) of 0.12 mm thickness and 1-9 mm gauge widths were prepared by rolling combined with annealing. The EBSD, digital image correlation technology, conventional tensile testing, in-situ tensile testing and SEM were used to analysis the effect of specimen width on the mechanical behavior of the H65-IF-H65 LMC. The results show that the H65-IF interface is mechanical bonded without elements diffusion during the annealing process. As the gauge width gradually reduced from 9 mm to 1 mm, the tensile strength and yield strength remain basically unchanged, meanwhile the total, the uniform, and the non-uniform elongations decrease from 30.3%, 23.4% and 6.9% to 20.3%, 18.8% and 1.5% respectively. The work hardening ability also decreases rapidly. Moreover, the strain of the H65-IF-H65 LMCs is gradually concentrated. On the tensile fracture, the width of the dimple band and the number and size of dimples within it also decrease significantly, which indicates a significant size effect. The main reason of sample sizes effect on the tensile behaviors of H65-IF-H65 LMCs is that the interaction of shear stress is inhibited with the decrease of the gauge width. The cracks are more likely to spread rapidly in the single shear band and result in a decreased ductility.
Prediction of elastic properties of short fiber reinforced composites based on machine learning
WANG Jiling, JIN Hao, GUO Ruiwen, SHI Chenxi, YANG Lifang, LI Meie, ZHOU Jinxiong
, Available online  
Abstract:
The elastic and mechanical properties of short fiber reinforced composites are significantly affected by their internal structure and the properties of the underlying materials, and the parametric analysis of these effects requires extremely high experimental or numerical analysis costs. In order to solve this problem, this paper combines the numerical homogenization method based on periodic representative volume units (RVE) and artificial neural network (ANN) to construct three forms of mechanical property prediction surrogate models of short fiber reinforced composites: spatial random distribution, intralayer random distribution and aligned distribution, respectively. Each surrogate model can quickly predict the equivalent elastic properties of composites under different parameter combinations (fiber length, aspect ratio, volume fraction, and fiber and matrix material properties), and the goodness of fit R2 is above 0.98, the calculation time is negligible compared to conventional simulation calculations, which greatly saves experimental and computational costs and creates important conditions for the design and customization of short fiber-reinforced composites.
Influence of multiple process parameters on the friction coefficient of prepregs and machine learning prediction method
SONG Feng, ZHANG Jiachen, LV Bingyi, WANG Shiyu, XIAO Jinyou, WEN Lihua, HOU Xiao
, Available online  
Abstract:
During the forming process of composites, the friction-sliding behavior between prepreg ply-ply and ply-tool may lead to defects such as wrinkles and pores, which seriously affect the mechanical properties of the components. However, there are many factors affecting the inter-ply friction of the prepreg plies in the forming process of complex components. The existing theoretical models contain insufficient process parameters, resulting in the accuracy of forming process simulation not meeting high-quality forming requirements. In this paper, a friction test method for carbon fiber prepregs was designed for multiple process parameters. The influence of sliding velocity, normal force, viscosity, surface roughness, contact material, and fiber orientation on the friction coefficient were studied. Taking the typical fiber orientations of \begin{document}$ {{\text{0}}^{\text{o}}}{\text{/4}}{{\text{5}}^{\text{o}}}{\text{/9}}{{\text{0}}^{\text{o}}} $\end{document} as examples, the inter-ply friction mechanism in different fiber orientations was revealed. In order to predict the friction coefficient of prepreg corresponding to multiple process parameters rapidly and accurately, a prediction model for the friction coefficient of prepreg was established using the support vector regression (SVR) method. Taking the prepreg ply-ply friction behavior with relative fiber orientation of \begin{document}$ {\text{[3}}{{\text{0}}^{\text{o}}}{\text{/}}{{\text{0}}^{\text{o}}}{\text{]}} $\end{document} and \begin{document}$ {\text{[6}}{{\text{0}}^{\text{o}}}{\text{/}}{{\text{0}}^{\text{o}}}{\text{]}} $\end{document} as examples, the experiments and predictions were conducted, and the error was less than 7%.
Research progress on energy absorption mechanism and damage mode of fiber reinforced resin based bulletproof composites
ZHAO Yun, YANG Bo, TAO Ziwei, NING Huiming, CHENG Yehong, HU Ning, ZHAO Libin
, Available online  
Abstract:
This article reviews the energy absorption mechanism and damage modes of fiber reinforced resin matrix composites in the field of impact resistance. Firstly, the applications of fiber reinforced composites in the fields of ballistic protection and aerospace are introduced. In addition, the advantages and disadvantages of high-performance fibers such as ultra-high molecular weight polyethylene fiber (UHMWPE), aramid fibers and carbon fibers are compared. Secondly, based on ballistic experiments and theoretical simulations of various fiber reinforced resin matrix composites, the energy absorption mechanism and damage mode of bulletproof composites are analyzed. It is found that tensile deformation is the main energy absorption mode of composites, and delamination is its main damage mode. Finally, the classification and characteristics of fabric structures and their influence on the ballistic performance of composites are summarized and the development prospect of fiber reinforced resin matrix composites is prospected.
Research progress of modified epoxy resin anticorrosive composite coatings
TONG Qingling, YANG Jianjun, WU Qingyun, WU Mingyuan, ZHANG Jianan, LIU Jiuyi
, Available online  
Abstract:
In the field of anti-corrosion, epoxy resin anti-corrosion composite coating is an excellent material to prevent metal corrosion. The epoxy coating forms a barrier between the metal and the corrosive ions, but the anti-corrosion effect of the epoxy resin does not last long during curing due to mechanical breakage and the formation of micropores. Three strategies for enhancing the anticorrosive properties of epoxy resin are introduced in this paper, namely nanoparticle modification, micro/nano container modification, and bio-based material modification. The research progress of epoxy resin anticorrosive composite coating modification is reviewed, and the future development direction of epoxy resin anticorrosive composite coating is prospected. In the future, a green epoxy anticorrosive composite coating with intelligent self-warning and self-repair, multi-function and cost-effective should be developed.
Simulation and experimental study of CFRTP orthogonal cutting considering the influence of temperature
WEI Gang, WANG Fuji, JIA Zhenyuan, JU Pengcheng, HU Xiaohang, FU Rao
, Available online  
Abstract:
Carbon fiber reinforced thermoplastic composites (CFRTP) is the preferred material for weight loss and efficiency improvement of high-end equipment. However, CFRTP is a typical difficult-to-machine material, and damage occurs frequently during processing. In this paper, the process of material removal and damage formation during cutting CFRTP was simulated and experimentally studied. CFRTP is prone to plastic deformation during cutting, and the material properties are greatly affected by temperature. In this paper, a three-dimensional orthogonal cutting simulation model of CFRTP was established, and the J-C model was introduced to characterize the elastic-plastic deformation of resin at different temperatures. The effects of temperature and fiber orientation angle on the cutting removal process of CFRTP were analyzed. The results show that when cutting at room temperature, and the fiber orientation angles are 0° and 45°, the machined surface is relatively flat and the processing quality is better; when the fiber orientation angles are 90° and 135°, the bending degree of the fiber increases obviously, and there are cracks on the machined surface, and the processing quality is poor. When cutting at room temperature, and the fiber orientation angle is 0°, the unremoved material appears on the machined surface; when the fiber orientation angle is 45°, cracks and fiber pull-out phenomenon appear on the machined surface. When the fiber orientation angles are 90° and 135°, the machined surface is more cracked, and the workpiece has obvious out-of-plane deformation along the thickness direction. The material with out-of-plane deformation is difficult to be effectively removed.
Preparation and characterization on carbon fiber composites with high thermal conductivity based on multifunctional intercalation structures
CAO Hongtao, CHENG Tao, SUN Zhenghao, CHEN Li, LI Yaoyao, HU Bingsheng
, Available online  
Abstract:
With the extensive application of carbon fiber reinforced resin matrix composites in aerospace field, structure/function integrated composites will play a crucial part. In this paper, asphalt based carbon fiber (CF) reinforced cyanate ester composites with high thermal conductivity were prepared by functional interlayer technology (Functional Interlayer Technology, FIT). The film material graphene sheets (GNPs)-Al2O3/CF prepared by electrophoretic deposition of GNPs and Al2O3 on the surface of the short-cut carbon fiber film was used as the functional interlayer film to replace the resin-rich layer region between the fiber layers. The in-plane thermal conductivity and through-plane thermal conductivity of orthogonal lamination composites are increased by 123.1% and 77.5%. The in-plane thermal conductivity and through-plane thermal conductivity of quasi-anisotropic lamination composites are increased by 119.0% and 50.0%, respectively. In addition, the addition of multifunctional intercalation structure can prevent the propagation of cracks and improve the interlaminar toughness of composites. Therefore, the multifunctional intercalation structure can not only form an effective thermal network structure between the layers to improve the in-plane and out-of-plane thermal conductivity of the composite, but also improve the toughening efficiency of the interlayer region.
Considering the influence of temperature and stress levels on the nonlinear creep model of GFRP in a water environment
ZHANG Yanfeng, LU Qi, LI Xingen, ZHU Sirong
, Available online  
Abstract:
This study investigates the influence of temperature and stress levels on the creep behavior of GFRP composite materials in deionized water environment. After treating the specimens with resin edge sealing, long-term creep tests were conducted at 20%, 30%, 40%, 50%, and 60% stress levels under 20°C, 30°C, 40°C, 50°C, and 60°C conditions using a constant load bending corrosion test machine. Furthermore, long-term creep tests were also performed at 20%, 30%, 40%, and 50% stress levels under 30°C conditions. The study separately examines the effects of different temperatures and stress levels on the creep performance of GFRP, quantifies the comprehensive impact of temperature and stress levels on the creep behavior of GFRP in deionized water environment, and establishes an improved Findley nonlinear creep model. Additionally, the study assesses the influence of deionized water environment on the interlaminar shear strength of GFRP using the short beam shear method. The results indicate that the improved Findley nonlinear creep model can accurately describe the creep performance of GFRP at temperatures ranging from 20°C to 60°C and below its creep fracture stress level, showing a broad applicability and high accuracy with good agreement with experimental results. Based on this model, the long-term creep performance of GFRP composite materials under different temperatures and stress levels in deionized water environment can be predicted, with prediction errors within 2%. Deionized water has minimal impact on the interlaminar shear strength of edge-sealed GFRP specimens. The findings of this study provide a basis for the design of GFRP structures.
Axial compressive property of 3 D braided-unidirectional hybrid tubes
SUN Houli, SUN Lin, WANG Xiaobo, CUI Jian, LI Zherui, ZHA Yibin, QIN Cheng, YAN Hongxia, LIU Yong, ZHANG Hui, YU Jianyong
, Available online  
Abstract:
Using the method of combining quasi-static axial compression experiment with finite element simulation, the axial compression characteristics and failure mechanisms of 3D braided-unidirectional ply (3D-UD) hybrid tubes were investigated. Test results show that the peak load, total absorbed energy and specific energy absorption (SEA) of 3D-UD hybrid tube are increased by 20.3%, 109.2% and 67.1% respectively compared to the UD tube, and the compression energy absorption mode becomes more stable. In addition, the failure process of 3D-UD hybrid tubes was simulated by finite element method. The results show that load-displacement curves curve are in good accordance with experiment results so that the reliability of the simulation model is verified. Combined with the experimental results and the simulation analysis of the damage deformation of the mixed tube, it is found that the binding and supporting effects of the outer layer 3D and the inner layer 3D on the sandwich UD inhibit the breakage of the UD tube wall due to excessive bending. At the same time, the stability failure and energy absorption of the sandwich UD tube prevent the 3D tube from serious braided layer crimp. Therefore, the mixed tube can effectively resist the wall deformation and improve the stability and energy absorption under axial compression.
Deep learning based tensile-shear damage evolution mechanism of quasi-isotropic satin weave C/SiC composites
CHEN Peng, WANG Long, ZHANG Daxu, DU Yonglong, GUO Weiyu, CHEN Chao
, Available online  
Abstract:
4D X-ray CT in-situ tensile testing, along with deep learning technology, was used to characterize the damage and failure process of quasi-isotropic lay-up satin C/SiC composites under tensile loading, and to reveal the damage evolution mechanism under the coupled action of (0°/90°) lay-up tension and (±45°) lay-up shear. Using the deep learning image segmentation method, damages were extracted for quantitative analysis based on intelligent detection of matrix cracks, delamination of the material under loading. Furthermore, damage and failure mechanisms were investigated by examining the fracture morphology. It is found that ±45° oblique cracks account for the major part of matrix cracks. Oblique cracks were mainly induced by small cracks at the initial loading stage. Although transverse cracks were less than oblique ones, their lengths and crack opening distance developed rapidly. Delamination was induced by the deflection of matrix cracks along the interfaces between adjacent layers. For a (0°/90°) satin lay-up, transverse split took place in the tissue point region of 90° fibre tows, and accompanied by bending in the floating length region of 90° fibre tows. Fractures occurred in the tissue point region of 0° fibre tows, and accompanied by longitudinal split in the floating length region of 0° tows. For a (±45°) satin lay-up, oblique split and relatively sliding occurred in −45° (or +45°) tows. While fractures accompanied by fibre tow bridging and bending took place in the +45° (or −45°) tows of the same lay-up.
Nonlinear transient heat transfer analysis of functionally graded material sandwich slabs by incremental differential quadrature element method
ZHANG Zhong, XU Jiajing, CAO Xiaojian, WANG Yanchao, ZHU Jun, YAO Lu
, Available online  
Abstract:
As a first attempt, the incremental differential quadrature element method (IDQEM) was adopted to perform the one-dimensional nonlinear transient heat transfer analysis of functionally graded material (FGM) sandwich slabs. The thermophysical properties of the slab were considered to be position- and temperature-dependent. To implement the IDQEM, the sandwich slab was divided into three spatial sub-domains along the layer interfaces, and the entire heating process was also divided into several temporal sub-domains. For each temporal sub-domain, the governing equations as well as the initial condition, interfacial condition, and boundary condition were discretized by the differential quadrature technique. Because the obtained discrete equations were built in different regions of grid points, a modification of the equations was proposed which were then expressed in the matrix forms so that they can be built in the same regions. Using the Kronecker product, the simultaneous matrix equations were transformed into a set of nonlinear algebraic equations, which were then solved by the Newton-Raphson iteration method to obtain the temperature profile for each temporal sub-domain. Because the initial condition of each temporal sub-domain was defined by the temperature results at the end of the previous sub-domain, the temperature profile of the slab during the entire heating process can be obtained by repeating the calculation procedure from the first temporal sub-domain to the last one. Numerical examples were carried out to verify the fast convergence of the present method. The correctness of the present method was verified through comparison with the analytical and numerical results reported in previous works. The effects of temperature-dependent thermophysical properties, volume fraction index, and thermal boundary on the temperature profile of the slab were discussed.
Extraction of plant long fiber and its application in biodegradable composites
HUANG Jingxu, LI Minwen, LI Zhihan, HUANG Haibo
, Available online  
Abstract:
Plant fibers have the advantages of eco-friendliness, lightweight, high strength, sound and heat insulating, and low carbon footprint, etc. These attributes make them highly sought-after for applications in sectors such as automotive, aerospace, construction, packaging, and transportation, particularly when plant fibers are processed into composites with polymers. This paper briefly describes the effects of the types of plant long fibers and extraction methods on their physical properties, and at the same time outlines the effects of plant long fibers on the physical properties of composites when they are used as reinforcement in combination with the fiber orientation distribution, fiber surface modification, composite molding process, and failure modes under tensile loading, as well as summarizes and looks forward to the application of plant long fiber-reinforced biodegradable composites.
Study on the mechanism of radiation heat dissipation behavior of rubber/steel cord composites based on multi-scale simulation
ZHOU Jiazhi, XIAO Huiping, XIE Xiaolin, ZHOU Zhisong, AN Lin, LI Wenbo
, Available online  
Abstract:
Heat transfer and temperature field analysis of rubber steel/cord composites are important for the study of vulcanization molding, thermo-oxidative aging, and thermal fatigue life of rubber products. In this paper, the heat transfer and heat dissipation mechanisms of rubber/steel cord composites with different steel cord ratios, laminate angles and temperature rise operating conditions are investigated based on a multi-scale heat transfer model and experimentally verified. The results show that the rubber/steel cord composites exhibit obvious anisotropic heat transfer behavior, and the heat flow aggregation effect at the heat transfer interface accelerates the interlayer diffusion of heat for more uniform temperature distribution. The radiative heat dissipation emissivity obtained from the simulation is as high as 0.95, and the radiative heat dissipation behavior is more pronounced as the percentage of steel cord increases and the temperature rises. Compared to the series-parallel heat transfer model, the prediction error of the multiscale heat transfer model is reduced from 10.1% to 2.5%.
Impact of the morphological evolution of SEBS based on external field effects on the mechanical properties of PPS composite materials
YI Chenghong, XIE Linsheng, JI Huajian, LI Guo, MA Yulu, WANG Yu
, Available online  
Abstract:
Polyphenylene sulfide (PPS) stands as a thermoplastic engineering material, renowned for its high strength and excellent stability. It has found extensive applications in both defense and civilian sectors. However, the intrinsic lack of toughness in PPS necessitates toughness enhancement for broadening its application scope, typically achieved through the incorporation of elastomers. In this study, a melt-blending technique utilizing a high-stretch chaotic flow rotor was employed to prepare hydrogenated styrene-butadiene-styrene block copolymer/polyphenylene sulfide (SEBS/PPS) composite materials. The research aimed to investigate the microstructural evolution of the materials under the influence of high-stretch external forces and analyze the impact of varying SEBS content on the mechanical properties of the PPS-based composite materials. The results indicate that with an increase in SEBS content, the impact strength and fracture elongation of the PPS-based composite materials exhibit an initial rise followed by a subsequent decline. When the SEBS content reaches 6wt%, the composite material demonstrates a ductile fracture behavior, achieving the highest impact strength and fracture elongation at 67.8 J/m and 6.1%, respectively. Microstructural analysis of the composite material reveals that within the SEBS content range of 0~6wt%, under the action of the high-stretch blending rotor, SEBS particles exhibit smaller and more uniformly distributed sizes. The droplet morphology undergoes a transition to elongated rod shapes, indicating a brittle-to-ductile transformation and a significant improvement in toughness. In the composite material with 6wt% SEBS content, multiple silver streaks are induced upon impact, leading to shear yielding and exhibiting plastic deformation. Continued increase in SEBS content intensifies the aggregation behavior of SEBS, resulting in an enlargement of particle sizes and broader distribution. At this stage, numerous void regions appear at the two-phase interfaces, triggering the development of silver streaks and concurrently causing fracture failure in the composite material, leading to a decrease in impact strength.
Preparation of curved carbon/carbon honeycomb and its mechanical properties under uniform load
WU Hao, LI Weijie, ZHANG Zhongwei, LIU Yu, LEI Yu, SHI Wentong, DONG Zhichao
, Available online  
Abstract:
With the increasing demand of precision instruments on the bearing platform structure, honeycomb structure has been widely concerned because of its light weight and ultra-high stability. In order to meet the requirements of the special-shaped composite bearing platform, this paper uses the combination of hot pressing and resin impregnation carbonization and chemical vapor deposition (CVD) to prepare the curved carbon/carbon honey-comb structure samples of different specifications. Then, according to the structural characteristics of curved honeycomb and the service environment, a test method of uniform load is designed to conduct compression tests on different samples. The influences of honeycomb thickness, layering angle and curvature radius on the mechanical properties of curved honeycomb were analyzed. The results show that when the radial thickness of honeycomb increases, the bending degree of honeycomb wall increases, the load on honeycomb double-walled space increases, and the cracking tendency of adhesive surface becomes more obvious. When the orientation of honeycomb fiber changes from 0° to 45°, the bending mode of honeycomb wall changes to non-buckling, ductile buckling and plastic buckling. When the curvature radius of curved honeycomb decreases, the failure mode gradually changes from decudation cracking to buckling fracture of honeycomb wall. The curved carbon/carbon honeycomb prepared in this paper has a compressive strength of 1.48 MPa, and has good mechanical properties, which can meet the requirements of increasingly complex aerospace structures.
Advances in silica aerogel composites and their research in aerospace
Mu Rui, LIU Yuanxue, LIU Xiaoying, ZHANG Yuxin, YAO Weilai, REN Junru, CHEN Jinfeng, CHENG Xinlei, YANG Xiuming, GONG Hongwei
, Available online  
Abstract:
As the most cutting-edge, basic and influential science and technology research field, the level of scientific research development is an important symbol to measure the innovation of national science and technology. However, aerospace thermal insulation materials are the most important technical support for the development of aerospace technology, and how to prepare materials with good thermal insulation properties and mechanical strength is of great significance for the development of aerospace technology. Silicon dioxide aerogel with ultra-low thermal conductivity, high porosity, high specific surface area and ultra-low density and other excellent properties, in the deep space probe, solar panels, space shuttle engines, solid rocket boosters and return capsule base and other special engineering equipment materials have a better application prospects.. In recent years, with the continuous development of silica aerogel research methods and preparation technology, by compounding it with functional materials with high strength and high temperature resistance, it can synergistically enhance its properties such as thermal insulation and mechanical strength, which is crucial for the development of aerospace special engineering materials. In view of this, this paper briefly describes the development history of silica aerogel, analyzes and summarizes in detail the research progress of aerogel composites formed by compositing silica aerogel with common oxides, fiber-reinforced and organic polymers and other reinforcing materials in the field of aerospace, and mainly comments on the preparation method, structural characteristics, heat insulation, mechanical properties, etc., and looks ahead to the problems, challenges, and future directions of the research and application of silica aerogel composites in this field.
Preparation of S−BiOI/BiOBr adsorption photocatalyst and its removal properties for 2,4−dichlorophenoxyacetic acid
YAO Dan, YANG Yi, ZHENG Anni, WANG Shaobing, YU Guanlong
, Available online  
Abstract:
Pesticide pollution of water body is a potential threat to human health. In this study, a new S0.1−(0.3/0.7)BiOI/BiOBr (S0.1BBI0.3) photocatalyst was synthesized by one−step solvothermal method. The structure, morphology and optical properties were characterized by XRD, SEM, XPS, UV−Vis DRS, EIS and other methods. S0.1BBI0.3 is a flower−like microsphere structure formed by the accumulation of two−dimensional nanosheets. Z−type heterojunction and S−doped dual−strategy co−modification broaden the photoresponse range of BiOBr, effectively prevent the photogenerated electron−hole pair recombination in S0.1BBI0.3, improve the photogenerated carrier redox ability, and increase the specific surface area. It provides more mesoporous structures, significantly improves adsorption properties, and provides more active sites for photocatalytic reactions. The photocatalytic experiment results showed that S0.1BBI0.3 had the best adsorption and photocatalytic performance for 2,4−dichlorophenoxyacetic acid (2,4−D) under visible light, and the removal rate of 2,4−D was up to 91.8% under 45 min darkness and 120 min light conditions. ESR technology confirmed that ·O2 is a photocatalytic active substance of S0.1BBI0.3.
Flexible capacitive pressure sensor based on carbon black/barium titanate/polyurethane
CHEN Xufeng, ZHANG Yu, QIN Yafei, WANG Mengyan, SUI Zhiyuan
, Available online  
Abstract:
With the rapid development and application of smart wearable flexible electronic technology in biomedicine, electronic skin, human-computer interaction and other fields, the research demand of flexible pressure sensors with high sensitivity and wide detection range has been put on the agenda. In this paper, a CB-BTO/PU flexible capacitive pressure sensor was prepared by using the polyurethane sponge (PU) as the base and combining CB-BTO/ BTO composite material on the polyurethane sponge by ultrasonic dipping coating. After testing, the sensor combines high sensitivity (~0.7911 kPa−1) and wide detection range (0~300 kPa). At the same time, the response time, the minimum detection limit and the stability of the sensor are studied. In addition, the sensor has been tested in four different pressure ranges, which verifies the potential of the sensor in high sensitivity and wide detection range, and provides a new possibility for low-cost and large-scale fabrication of high-performance flexible sensors.
Effects of high temperature heat treatment on the micro structure and mechanical performance of C/C-SiC composite materials
MA Fei, LUO Hao, SUN Shouye, SHI Xiangdong, LUO Ruiying, GUO Lingyan
, Available online  
Abstract:
The microstructure and properties of C/C-SiC composites prepared by reactive melt infiltration (RMI) are significantly affected by post-heat treatment. In order to study the effect and mechanism of post-heat treatment on the microstructure and mechanical properties of C/C-SiC composites prepared by RMI, the isothermal chemical vapor infiltration (CVI) process was used to deposit pyrolytic carbon matrix in the carbon fiber preform, and C/C porous bodies with a density of 1.2 g/cm3 were prepared by using natural gas as carbon source gas and nitrogen as carrier gas and dilution gas. Then C/C-SiC composites were prepared by reactive melt infiltration method. The effects of different post-heat treatment temperatures on the phase composition, internal stress and mechanical properties of C/C-SiC composites were studied. The prepared C/C-SiC composites were treated at 1300℃, 1500℃ and 1700℃ respectively. The effects of post-high temperature heat treatment on the density, porosity, matrix composition, internal stress and bending properties of the C/C-SiC composites were investigated. The results show that after heat treatment at 1300℃, 1500℃ and 1700℃, the density of C/C-SiC composites decreases, the porosity increases, the content of SiC matrix increases, the distribution of SiC matrix becomes more extensive, and the residual Si content decreases significantly with large pores caused by residual Si volatilization. At 1300℃, 1500℃ and 1700℃, the bending strength increases first and then decreases. At 1500℃, the bending strength reaches a maximum of 296.52 MPa. With the increase of the post-treatment temperature, the bending modulus decreases, and at 1700℃, the bending strength decreases the most.
Preparation and microwave absorption properties of ultra-fluffy doped graphene aerogel composites
REN Peiyong, CHEN Miao, ZHAO Ke, GAO Xiaoping
, Available online  
Abstract:
With the rapid advancement of intelligent communication, the issue of electromagnetic radiation caused by information transmission is becoming increasingly severe. However, traditional microwave absorption materials have limitations such as poor attenuation ability and difficulties in impedance matching, which no longer meet practical applications. In this paper, graphene aerogel (GA) was prepared by hydrothermal synthesis based on the theory of electromagnetic loss, the design strategy of multi-component synergistic loss and the construction of three-dimensional porous aerogel. To enhance its properties, we incorporated MnO2-coated Ni-Zn ferrite (NiZnFe2O4@MnO2) microspheres with graphene dielectric material to prepare ultra-fluffy magnetically doped graphene-based composite aerogel (NiZnFe2O4@MnO2/GA) powders. The impact of heat treatment temperature and magnetic doping on the wave absorption capability of the composite aerogel was analyzed. Our results demonstrate that at a heat treatment temperature of 300 ℃ and a nickel-zinc ferrite doping amount of 15 wt%, the composite aerogel exhibits optimal absorption performance. At a matching thickness of 2.9 mm, it achieves a minimum reflection loss (RLmin) value of -47.27 dB at a frequency of 8.72 GHz, providing an effective absorption bandwidth (EAB) spanning 3.2 GHz covering most X-band frequencies while maintaining only a packing load rate of 10 wt%. The problem of poor material impedance matching is solved, the dielectric loss and magnetic loss capacity of the absorbing materials are optimized,The application requirements of the wave absorbing material for "thin, light, wide and strong" are met.
Cement-based structural batteries: mechanism, influencing factors, and application
XIE Wenjian, GAO Wanyang, HU Nantao
, Available online  
Abstract:
Structural energy storage integrated composite materials provide an innovative approach to the integrated development of structure and energy storage. Using cement-based materials as a structural electrolyte and combining it with electrode material can produce cement-based structural batteries. This review paper provides an overview of research on cement-based structural batteries. The paper introduced the conductive and discharge mechanism and discussed the key factors that affect resistivity and discharge performance from the major aspects of electrode and electrolyte. Research indicates that cement-based structure batteries can achieve a voltage of 1.5 V and a capacity density of 8.45×105 mA·h·m−1, and are rechargeable. With the characteristics of integrated structural and energy storage functions, it demonstrates the potential for applications in energy storage green building, smart concrete, and energy-harvesting concrete. Finally, the paper points out current problems and future research directions.
Flexible capacitive pressure sensor with a wide detection range based on porous carbon nanotube、carboxyl iron powder/silicone composite
YUAN Lin, HUNG Chengyi, HUANG Pei, LI Yuanqing, FU Shaoyun
, Available online  
Abstract:
Featured by simple structure, fast response, high sensitivity, and low cost, etc., flexible capacitive pressure sensor has been widely used in the fields of health care, robotics, wearable devices and so on. However, the trade-off between the effective upper and lower detection limits greatly restricts the applications of the flexible capacitive pressure sensor. In this work, a flexible and porous carbon nanotube (CNT)/carbonyl iron particle (CIP)/silicone composite was produced by using sugar particles (SPs) as the as pore-forming agents, CIPs as the magneto-responsive fillers, CNTs as the conductive fillers and silicone rubber as the flexible matrix. After serving as the dielectric layer, the porous CNT、CIP/silicone composite endows the capacitive pressure sensor produced a wide effective detection range of 0.07-180 kPa (at the frequency range of 0-5 Hz), much wider than most capacitive pressure sensors reported. In virtue of the wide detection range, long-term stability and fast response, the sensor produced is capable of monitoring human breath, arm movement, talking, and robotic movement, thus showing great promise in health monitoring, wearable electronic devices, and intelligent robotics, etc.
Preparation and properties of Silicone polymer-Graphene oxide reinforced glass fiber/epoxy resin composites
XU Huan, YE Bei, LU Jing Jing, GUAN Ji Peng, DANG Rui Qiong, SHEN Xiao Jun
, Available online  
Abstract:
In this study, different proportions of Silicon polymer-Graphene oxide (PSOL-GO) were used as nano-fillers to modify Glass fiber/epoxy resin(GF/EP )composites, the composites with different PSOL-GO contents were prepared, The microstructure and strengthening mechanism of epoxy composites were analyzed by observing morphology, measuring contact Angle, infrared analysis, mechanical properties and dynamic mechanical analysis (DMA). The experimental results show that the mechanical properties of PSOL-GO@GF/EP composites are the best when the ratio of PSOL-GO is 1∶0.1: The interlayer shear strength of modified GF/EP composites is 13.19% higher than that of pure GF/EP composites; Its bending strength increased by 33.12%; Its tensile strength increased by 35.32%; Its impact strength increased by 16.95%. The glass transition temperature (Tg) of GF/EP composites was increased by 7.1℃ by adding PSOL-GO at 1∶0.1 ratio, and the heat resistance of GF/EP composites was improved. The epoxy resin with the introduction of PSOL-GO nano-filler has better wettability to glass fibers, and can fill the gap of pure GF/EP composite itself to enhance the performance of the composite materials.
Adsorption performance and mechanism of MnO2/Ti3C2TX composite towards U(VI) in water
ZHOU guolin, XIE shuibo, HU lian
, Available online  
Abstract:
To address the shortcomings of Ti3C2TX nanosheets, which tend to stack and have limited adsorption sites, a MnO2/Ti3C2TX composite was prepared using the hydrothermal method. The influence of uranium initial concentration, dosage, pH, time, and interfering ions on U(VI) adsorption was investigated through single-factor adsorption experiments. Modern characterization techniques were employed to analyze the surface properties of MnO2/Ti3C2TX and the mechanism of U(VI) adsorption. Experimental results revealed that with an initial U(VI) concentration of 5 mg·L−1, MnO2/Ti3C2TX dosage of 0.1 g·L−1, and a temperature of 303 K, pH of 6, the U(VI) concentration dropped to 0.41mg·L−1 within 30 seconds. Adsorption equilibrium was reached after 30 minutes, with an adsorption rate of 99.15% and an adsorption capacity of 49.58 mg·g−1. After five cycles, the adsorption efficiency of MnO2/Ti3C2TX remained at 96.3%, demonstrating its potential for regeneration and reuse.The entire adsorption process was endothermic and spontaneous, fitting the pseudo-second-order kinetic model and the Freundlich isotherm model. BET analysis showed that the specific surface area of MnO2/Ti3C2TX reached 318.3 m2·g−1, which is 55.9 times higher than that of Ti3C2TX. FTIR and XPS analyses indicated that the primary mechanism of U(VI) adsorption on MnO2/Ti3C2TX is the coordination complexation between surface oxygen-containing groups and uranium.
Research progress of electrolytes for aluminum ion batteries
LEI Xin, CHENG Cheng, SUN Tao, FAN Hognyu, SHEN Xuejing, WU Zhanjun
, Available online  
Abstract:
Due to the rapid development of society, demands for secondary ion batteries are gradually increasing. Aluminum-ion battery has a lot of advantages, such as low cost, high safety and good cycle performance. Thus, it is an ideal energy storage system to replace lithium-ion battery in the future. As an important component of battery system, electrolyte plays a key role in transferring ions and connecting circuits, and has a direct impact on battery performance. Therefore, designing and preparing of electrolytes with good overall performance has become a research hotspot in aluminum-ion batteries. This article summarizes the current research status of liquid electrolytes, inorganic solid electrolytes and polymer electrolytes for aluminum-ion batteries, analyzes their performance in terms of cost, electrochemical window, chemical stability and ionic conductivity. The future development direction of aluminum-ion battery electrolytes is prospected.
Research on the Uranium ion Removal Performance of Polyethyleneimine/Ramie Fiber Self-Supporting Membranes
ZHANG Shuang, TANG Yong, AN Zaixu, CHEN Xixi, NA Bing, LIU Hesheng, LIU Yuhui
, Available online  
Abstract:
In order to deal with the increasingly serious energy and environmental pollution problems, the treatment of uranium containing wastewater has become an urgent matter. In order to treat uranium containing wastewater efficiently and conveniently, polyethylenimide/ramie fiber self-sustaining membrane (PEI/RAM) was prepared by grafting polyethylimide (PEI) onto ramie fiber after treatment with low eutic solvent (DES, choline chloride-oxalic acid system), and was used to remove uranyl ion (UO22+) in aqueous solution. The effects of initial concentration of UO22+, pH value of solution, adsorption time and temperature on the properties of the adsorbent were studied. When the initial concentration of uranyl ion is 20 mg/L and the solution pH is 6, the adsorption equilibrium capacity of uranium reaches 302 mg·g−1. The uranium adsorption process of PEI/RAM is closer to Langmuir model and quasi-second-order kinetic model. In the presence of interfering metal ions (Ca2+, K+, Mg2+, Na+), the polyethylenimide/Ramie fiber self-supported film (PEI/RAM) adsorbent showed good selectivity for uranyl ions, and its adsorption capacity for UO22+ (20 mg/L) was nearly 70 times that of other metal ions (20 mg/L).
Electromagnetic performance and microstructure of amorphous/Fe-Si soft magnetic composites
GUO Hai, NIE Min, YANG Yiting, ZHAO Fengxiang, HE Jiayi
, Available online  
Abstract:
This work optimizes the electromagnetic properties of Fe-Si based soft magnetic composites by both modifying the composition and particle size distribution. The relationship between soft magnetic properties and microstructure is investigated. Great comprehensive electromagnetic properties can be obtained by firstly composing the Fe-Si powders with different sizes, and then partly replacing the coarse Fe-Si powder by Fe-Si-B-C amorphous powder with similar particle size. The amorphous/Fe-Si soft magnetic composites have good frequency stability within 1 MHz. When the mass ratio among Fe-Si-B-C amorphous powder, Fe-Si coarse powder, Fe-Si fine powder is 25∶25∶50, the effective permeability at 100 kHz is 47.6, the DC bias capacity at 100 Oe is 79.5%, and the power loss at 100 kHz/100mT is 1806 mW/cm3. Compared with other reported amorphous-containing soft magnetic composites, the amorphous Fe-Si-B-C/Fe-Si soft magnetic composites in this work have significant advantages in cost and combined electromagnetic properties. The Fe-Si fine powder can fill the gap between the coarse powder, which is conducive to improving the density and permeability of the soft magnetic composite, while the addition of amorphous powder can significantly reduce the power loss. The amorphous/Fe-Si soft magnetic composites prepared in this work have good comprehensive electromagnetic properties and can provide potential solutions for industrial production.
Pore structure and mechanical properties of steel fiber reinforced geopolymer recycled aggregate concrete
LI Zhenjun, LIU Xi, ZHAO Chenyu, WANG Chi, TIAN Xin
, Available online  
Abstract:
To study the pore characteristics and macroscopic performance of steel fiber reinforced geopolymer recycled aggregate concrete (SFGRC), the internal pore structure, mechanical properties and shrinkage performance of SFGRC were tested. The influences of recycled aggregate content and calcium silicon ratio on the pore structure, strength, stress-strain curve shape and characteristic parameters of concrete were analyzed. Based on fractal theory, a correlation model between pore structure and the macroscopic performance of SFGRC was established. The research results indicate that recycled aggregate significantly increases the porosity and harmful pore proportion of SFGRC and deteriorates its mechanical properties. The high ground granulated blast furnace slag (GGBS) content refines the pore structure of SFGRC, increasing the complexity of the material's pore size and spatial distribution. The GGBS and recycled aggregate significantly increase the shrinkage rate of SFGRC. The pore structure of SFGRC exhibits obvious fractal characteristics, with fractal dimensions ranging from 2.623 to 2.731. It strongly correlates with pore structure characteristic parameters and mechanical properties, which can effectively evaluate the pore structure characteristics of SFGRC. A prediction model based on fractal dimension for characteristic parameters such as SFGRC elastic modulus, ultimate stress, ultimate strain and drying shrinkage was established using the Bayesian- markov chain monte carlo (Bayesian-MCMC) method, with a goodness of fit of 0.51-0.98 and high prediction accuracy. This provides a theoretical basis for optimizing the pore structure and macroscopic performance of GRC concrete.
Construction and drug release performance of thermosensitive copolymer-modified hollow mesoporous silica and the composite nanofibers
PEI Wenxiang, MA Shijie, YANG Langfei, GAO Yujie, WU Jindan
, Available online  
Abstract:
Traditional drug-loaded nanofibers face challenges such as unstable drug loading and excessively rapid release. In light of these issues, this study employs a thermosensitive copolymer (P(NIPAM-co-AM)) to coat hollow mesoporous silica nanoparticles (HMSN), incorporating them as drug carriers in conjunction with poly(ε-caprolactone) (PCL) nanofibers. The drug release and antibacterial performance of the composite nanofiber membrane were investigated. Firstly, the HMSN surface was functionalized through free radical polymerization by grafting a copolymer of isopropylacrylamide (NIPAM) and acrylamide (AM) (P(NIPAM-co-AM)). Hydrophobic drug ciprofloxacin (CIP) was loaded into the modified nanoparticles (P(NIPAM-co-AM)-HMSN or PHMSN). The analysis of the microstructure, composition, and temperature-responsibility of the drug-loaded particles were performed using SEM, TEM, TG, BET analysis, FTIR, UV-Vis spectroscopy, etc. Blending PCL with drug-loaded PHMSN, a composite fibrous membrane (CIP@PHMSN-PCL) was fabricated using electrospinning. CIP@PHMSN-PCL exhibited temperature-stimulated drug releasing, with cumulative release rates of CIP reaching 90.78% and 72.67% at 45℃ and 25℃ after 72 hours, respectively. The Korsmeyer-Peppas model aptly described the drug release kinetics, suggesting the diffusion as the primary mechanisms for drug release from the composite fiber membrane. At 45℃, the drug-loaded fiber membrane exhibited a 100% inhibition rate against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). At 25℃, the inhibition rates were 92.34% and 95.83% against E. coli and S. aureus, respectively, demonstrating temperature-dependent drug release performance of the CIP@PHMSN-PCL membrane. In summary, the drug-loaded PHMSN composite nanofiber membrane exhibits temperature-regulated drug release functionality and excellent antibacterial activity, holding potential application value in the biomedical field.
Research progress of hydrogen permeation palladium composite membranes
ZHU Xiaoxin1, ZHANG Zhenqiang, CAO Mei, TIAN Yiran, HAN Fei, ZHANG Bin
, Available online  
Abstract:
Palladium composite membranes have highly selective permeability to hydrogen due to their special dissolution/diffusion mechanism of hydrogen permeation, and are an ideal material for hydrogen separation in membrane reactors. In order to promote the research and application of palladium composite membranes with high hydrogen permeability and stability, the preparation method of the membranes via electroless plating and its combined with other methods, and different types of the membranes are reviewed in this paper. Electroless plating is the most common preparation method of palladium composite membranes, and the quality of the membranes can be improved by combining with vacuum and continuous flow. Using group ⅤB metals, porous ceramics and stainless steel as the matrix of electroless Pd membranes, the membrane thickness can be reduced, mechanical strength and hydrogen permeability can be improved; The thickness of Pd membranes can be further reduced by adding refractory oxide, zeolite, natural mineral and polymer between Pd membrane and porous matrix, and the thermal and chemical stability can be improved. Compared with pure Pd membrane, Pd-Ag, Pd-Cu, Pd-Au binary alloy membranes and Pd-Au-Ag ternary alloy membrane have no hydrogen embrittlement phenomenon at low temperature, and can improve the hydrogen permeability and sulfur resistance of Pd membranes to a certain degrees. Finally, the future research direction of palladium composite membranes is prospected.
Study on plastic yield strength of gyroid lattice structures based on functional principleson
WU Fenghe, WANG Chaoshi, SUN Yingbing, LIU Lei, ZHANG Tongqing, WANG Zhaohua
, Available online  
Abstract:
One of the differences in mechanical properties between lattice structures and dense structures lies in the plastic yield response. Therefore, studying their yield behavior can provide important theoretical basis for the design and application of lattice structures. Firstly, The Gyroid lattice structure was simplified and its mechanical model was established based on the principle of deformable body function, obtaining the mapping relationship between the plastic yield strength and volume fraction of the Gyroid lattice structure. Then, based on the finite element analysis software Abaqus, simulation experiments were conducted on the quasi-static compression process of Gyroid lattice structures to preliminarily verify the accuracy of the theoretical model. Finally, different volume fractions of 316L stainless steel Gyroid lattice structures were prepared by selective laser melting (SLM), and uniaxial compression experiments were conducted to analyze their deformation mechanism and mechanical properties. The results show that the error between theoretical derivation, finite element simulation results and experimental results is within 25%, and the coefficients of the Gibson-Ashby model fitted based on the results of the three methods have good consistency, indicating the effectiveness of the Gyroid lattice structure plastic yield strength prediction model established based on theoretical derivation. The construction method of theoretical models can be transformed into other complex types of lattice structures, providing a theoretical basis for quickly calculating the mechanical properties of lattice structures and applying them in engineering equipment.
Performance and mechanism of biochar loaded magnetic nanocarbon hydroxyapatite(CHAP-γ-Fe2O3/BC) for the removal of U(VI) from water
SHAO Xiongbin, XIE Shuibo, MAI Yingqing, JIANG Peixuan
, Available online  
Abstract:
To address the efficiency of removing U(VI) from water using functional materials and the susceptibility of nanoparticles to agglomeration, biochar-loaded magnetic nanocarbon hydroxyapatite (CHAP-γ-Fe2O3/BC ) composites were prepared by dynamic oil-heating and impregnation methods using corn stover, egg shells, and magnetic γ-Fe2O, and the experiments were carried out to investigate the performances and used for the removal of U(Ⅵ) from water. When the initial concentration of U(Ⅵ) is 5 mg/L, the dosage of CHAP-γ-Fe2O3/BC is 0.1 g/L, the pH value is 6, the temperature is 30°, and the reaction time is 1 h, the experimental results show that the maximum adsorption capacity of CHAP-γ-Fe2O3/BC for U(Ⅵ) reaches 324.4 mg/g, and the removal rate reaches 95.93%. The proposed secondary kinetic model and Langmuir model could fit the adsorption process of CHAP-γ-Fe2O3/BC on U(Ⅵ) better, indicating that the monomolecular layer chemisorption is dominated. The materials are realized to attenuate the agglomeration by surface modification technique. The composite material shows good separation recovery and recyclability in the magnetic field. The characterization results of FTIR and XPS prove that the removal mechanism of uranium by this material mainly includes ion exchange, dissolution-precipitation chemisorption and surface complexation.
Preparation and properties of micromodulation-based polypropylene/polybutylene terephthalate/carbon nanotube electromagnetic shielding materials
ZHANG Xu, XIE LinSheng, ZHU HuiHao, LI Guo, MA YuLu, WANG Yu
, Available online  
Abstract:
The electromagnetic pollution caused by electronic equipment to the external environment has become another major public hazard after noise pollution, air pollution, water pollution and solid waste pollution, so the research and development of high-performance electromagnetic shielding materials has become a hot spot in materials science research. In this paper, the phase domain size of the polymer phases in the PP/PBT/CNTs blends was regulated by adjusting the blending methods of polypropylene (PP), polybutylene terephthalate (PBT) and carbon nanotubes (CNTs) during the melt blending process. The influence of the microscopic morphology of the composites on their electromagnetic shielding properties was studied by morphology analysis, dynamic rheology and crystallization behavior tests. The results show that compared with the PP phase, CNTs have a stronger affinity for the PBT phase, and are always located in the PBT phase domain among the four blending methods. When the PP/PBT/CNTs composites are prepared by PP/CNTs masterbatch method, the phase domain size of the PBT inside the obtained composites is smaller, the compatibility between PP and PBT is higher, the conductive path and interface area are significantly increased, and a denser and uniform conductive network structure is formed inside the composites, so the conductivity of the prepared polymer matrix composites is significantly improved, reaching 29.60 s/m, and the electromagnetic shielding efficiency is in the X-band (8.2-12.4 GHz) to 35.6 dB, far exceeding the demand for commercial electromagnetic shielding materials.
Preparation of polyvinylpyrrolidone water-based hybrid coating and its sizing treatment of recycled glass fiber
SHEN Yang, XIE Jiaqi, FU Yaqin
, Available online  
Abstract:
In order to effectively utilize recycled glass fiber, two polyvinylpyrrolidone water-based hybrid coatings were synthesized under acid catalysis and without adding catalyst using ethyl orthosilicate and coupling agent as precursors and polyvinylpyrrolidone as film-forming agent. The recycled glass fibers were sized separately using the prepared hybrid coatings. The results showed that the surface roughness of the recycled glass fibers after the sizing treatment of the hybrid coatings prepared under acid-catalyzed conditions was greater compared with that of the hybrid coatings prepared under the condition of no added catalyst; The single-fiber tensile strengths of the recycled glass fibers after sizing treatment of the hybrid coatings prepared under acid-catalyzed conditions and conditions without added catalysts were 1322.7 ± 98.5 MPa and 1093.8 ± 53.8 MPa, which were increased by 39.8% and 15.6%, compared with the single-fiber tensile strengths of the recycled glass fibers. The use of single fiber fragmentation method to evaluate the interfacial properties of recycled glass fiber and epoxy resin shows that single fiber epoxy resin composite materials prepared from recycled glass fiber after sizing with hybrid coating prepared under acid catalytic conditions and without adding catalytic conditions The interfacial shear strengths are 53.5 MPa and 35.7 MPa respectively, which are 200.5% and 100.8% higher than the interfacial shear strengths of single fiber epoxy resin composites of recycled glass fibers without sizing treatment. Aqueous hybrid coatings prepared under acid-catalyzed conditions are shown to be feasible for recycling glass fibers.
Carboxymethyl cellulose-MgCl2 composite based humidity sensor: self-powered, flexible, and multifunctional sensing applications
WANG Haoxiang, TANG Chengli
, Available online  
Abstract:
Humidity sensors have been widely used in fields of agriculture, industrial production, precision instruments and human health monitoring. To address the problem that humidity sensors need to be driven by an external power source, a self-powered flexible humidity sensor based on the principle of primary battery was proposed in this paper. The carboxymethyl cellulose with moisture-sensitive properties and MgCl2 with moisture-absorbent properties were applied as the sensitive layer. And commercialized conductive copper and nickel adhesive tapes were used as the positive and negative electrodes. The micro-morphology and surface elements of the sensitive layer of the sensor were characterized by SEM and EDS, the moisture sensitivity mechanism was analyzed based on complex impedance spectroscopy, and the multifunctional applications of the sensor was demonstrated. The sensor sensitive layer has good hydrophilicity, which can ionize the MgCl2 in it to produce carriers such as Mg2+ and Cl after contacting the water molecules in the environment. The directional movement of these carriers can generate output voltage. The response value can reach 177% when the relative humidity changes from 11% to 95%. The sensor can be used for human respiratory frequency and characteristic detection, soil moisture and urinary moisture detection, finger distance detection, and providing electrical energy. Experimental results show its potential for applications in health monitoring, environmental humidity monitoring, non-contact switching, and power-supply areas.
Influence of the rheological properties of paste on the early-age tensile creep of high-volume fly ash concrete
NI Tongyuan, YAO Shuifeng, CHEN Weizhong, YANG Yang, LIU Jintao, NIE Haibo
, Available online  
Abstract:
It is one of important factors affecting on concrete tensile creep that the rheological properties of concrete paste. The microscopic mechanical properties and rheological characteristics of cementitious paste containing high volume fly ash (60%) were analyzed by nanoindentation. And the same time, the tensile creep law dependent on ages of high-volume fly ash concrete containing same cementitious paste was experimental studied. The predictive function expressions of the HVFAC tensile creep considering the rheological properties of paste were proposed. The nanoindentation results show that the fly ash promotes the paste’s micro creep development of paste at the same test ages, and the micro creep of paste tends to converge quickly with the delay of test age which the cement is replaced with the same quality fly ash. The influence of fly ash and loading age on the development of HVFAC creep is consistent with the influence law of cementitious paste’s micro creep without aggregate. Base on the correlation analysis on the parameters of Et,28d/(EV+EH), Et,28d/χφ, φ and relative compressive strength fc(t0)/fc,28d, the parameters of C, τ and test ages, it shows that these parameters are in good agreement with the function y = axb. The tensile creep prediction expression of ZC model considering the rheological properties of cement paste can reflect the structure of the model unit cell.
Advances in photoelectrocatalysis and artificial photosynthesis for the reduction of CO2
LIU Jinrui, ZHANG Yan, SUN Shishu, SHI Jianjun, SUN Tianyi, SHI Zaifeng
, Available online  
Abstract:
With the continuous development of industrialization, CO2 produced by the excessive use of fossil fuels has led to problems such as the greenhouse effect, which has attracted great attention from the international community and a series of countermeasures have been formulated. Therefore, the research and development of technology for the reduction and recovery of CO2 from the atmosphere is urgent and important. Photoelectrocatalysis is one of the technologies with good application prospects that can be used to reduce CO2. In order to carry out a more in-depth research on this technology and promote its practical application, this paper firstly describes the basic principles and advantages and disadvantages of photocatalysis, electrocatalysis, and photoelectrocatalysis for CO2 reduction, and gives examples of the efficiency of various types of catalysts for CO2 reduction. Because photocatalysis is one of the important steps in photosynthesis, it then focuses on analyzing the current status and prospects of photosynthesis in reducing CO2 research, and proposes the feasibility and potential of artificial photosynthesis for CO2 reduction. The aim of this paper is to provide new ideas and references for the reduction of CO2 by artificial photosynthesis, and to provide new insights and perspectives for reducing the accumulation of CO2 in the atmosphere and addressing current environmental challenges.
Research Progress of Magnetic Silicate Nanomaterials for Photocatalytic Degradation of Organic Pollutants
ZHU Hao, DU Chunyan, CAO Jiao, ZHOU Lu, YU Guanlong, YAN Rong, YANG Yu
, Available online  
Abstract:
Photocatalysis is an effective method for removing recalcitrant organic pollutants from water, demonstrating significant potential due to its high mineralization efficiency. However, the practical application of most photocatalysts is hindered by their powder form, posing challenges for large-scale use. Recently, magnetic silicate composite materials have garnered increasing attention in the field of materials science due to their stability and recyclability. In this review, we examine the current state of research on magnetic silicate composite materials as photocatalysts, exploring the latest advancements in synthesis, modification, and degradation mechanisms. Finally, we provide an outlook on the research findings and future challenges associated with magnetic silicate composite materials.
Research progress on the regulation of filler particle alignment during physics-assisted 3D printing
LI Yang, ZHENG Xinmei, MEI Xin, REN Yan, CHEN Gang, PENG Biyou
, Available online  
Abstract:
3D printing is a bottom-up, layer-by-layer material additive manufacturing technique. Currently, 3D printing is evolving from prototype manufacturing towards high-performance and functionalization, placing higher demands on the control of printing materials and processes. The orderly arrangement of nanoparticles in 3D printing materials is crucial for enhancing the performance of printed components, yet effectively controlling the orientation of nanoparticles remains challenging. Incorporating physical fields (magnetic, electric, and ultrasonic fields) into the 3D printing process emerges as one of the effective strategies for precise microstructure manipulation of printed items. This approach not only endows the printed components with specific functions but also provides new insights for fabricating multi-scale and multi-responsive structured components. Therefore, physical field-assisted 3D printing has become a research hotspot in recent years. This article begins by briefly describing the types and characteristics of 3D printing technology, emphasizing the importance of physical field assistance in controlling the orientation of nanoparticles. Subsequently, it reviews and summarizes the fundamental principles, material requirements, applications, and performance of physical field-assisted 3D printing in controlling nanoparticle orientation. Finally, the problems and challenges existing in controlling the orientation of filler particles in physical field-assisted 3D printing are summarized, and its future development direction is prospected.
Low frequency bandgap characteristics and application of a novel two-dimensional three-component cement-based phononic-like crystal composite material
XIAO Peng, MIAO Linchang, ZHENG Haizhong, LEI Lijian
, Available online  
Abstract:
In order to widen the width and number of elastic bandgap of concrete metamaterials, a novel two-dimensional three-component cement-based phononic-like crystal was designed based on local resonance theory. Firstly, the finite element method was used to calculate and study the energy band structure, vibration mode, displacement field and attenuation characteristics of the novel two-dimensional three-component cement-based phononic-like crystal. Secondly, the formation mechanism and influencing factors of the bandgap were analyzed, and the theoretical estimation of the bandgap range was derived according to the mass-spring system model. Finally, the cement-based phononic-like crystal was applied to the subway track bed, and the vibration reduction performance of the cement-based phononic-like crystal subway track bed was analyzed. The results show that the novel two-dimensional three-component cement-based phononic-like crystal opens 5 low-frequency bandgaps in the 200 Hz frequency range, and the attenuation values are mostly above 10 dB within the bandgap frequency range, and the attenuation effect is good. The opening of the bandgap corresponds to the vibration characteristics of each primitive cell, which is triggered by the translational vibration of a specific primitive cell and controlled by the strength of the coupling between the specific primitive cell and the matrix. The density of scatterer material, elastic modulus and thickness of cladding material are the main factors affecting the bandgap. In the 1-200 Hz frequency band, the vibration acceleration of the cement-based phononic-like crystal subway track bed composed of the novel two-dimensional three-component cement-based phononic-like crystal is lower than that of the ordinary concrete subway track bed, and the maximum insertion loss is 10.22 dB and the average insertion loss is 8.76 dB, which has remarkable vibration reduction performance.
Biomass carbon tubes/kaolin rock - dual wastes derived composite for efficient microwave absorption
KONG Xiangkai, WU Peikun, YAN Han, ZHENG Fangyu, WANG Lizhi, LIU Qiangchun, JU Zhicheng
, Available online  
Abstract:
Low cost, high performance, and good environmental stability are the key factors to determine the application of microwave absorbent. In this study, the wasted platanus tree fruits were taken as raw biomass materials, which were combined with the kaolin rock, one kind of abandoned coal mine resources, to construct the dual wastes-derived composite for microwave absorption. The obtained carbon microtubes/kaolin rock composite was optimized by controlling their interfacial interaction followed by high-temperature pyrolysis to reach efficient absorbing capability towards microwave radiation. The experimental results showed that the acid-modified carbon microtubes (CMT-ac) and the alkali-decorated kaolin rock (KR-al) combined well to supply a large number of heterogeneous interfaces to strengthen the interfacial polarization mechanism. As a result, their conductivity difference under the irradiation of electromagnetic wave enabled greatly attenuating electromagnetic wave. The final KR-al@CMT-ac sample achieved an effective absorption bandwidth of 6.3 GHz (11.7~18.0 GHz) at a matching thickness of only 2.0 mm and a minimum reflection loss of -51.5 dB at 8.08 GHz at a thickness of 3.0 mm. The improvement in microwave absorption performance is due to the enhanced interface polarization and conduction loss. This study will provide an effective strategy for the design of low-cost and high-performance dielectric absorbents.
Design and processing of wear-resistant and ice-resistant PTFE surface
HE Zhihao, ZHANG Bingzhen, PAN Weihao, SUN Jing, SONG Jinlong
, Available online  
Abstract:
The icing on the surface of the silo of the ice jet cleaning equipment often causes the equipment to shutdown for maintenance, but how to reduce the icing adhesion on the silo surface is a difficulty of current research. In this work, CO2 laser was used to etch polytetrafluoroethylene (PTFE) to obtain a superhydrophobic surface, and a rhombus support rib array structure was designed to improve the wear resistance of the superhydrophobic PTFE surface. CO2 laser etching could form a multi-layer staggered stacked fiber structure on the PTFE surface, and there was no obvious change in the chemical composition of the surface after laser etching. The superhydrophobic PTFE surface with contact angle of 164° and rolling angle of 4° can be obtained at laser scanning line spacing of 50 μm, scanning speed of 300 mm/s, and laser power of 9 W. The designed rhombus support rib array structure with crest angle of 30°, length of side of 3 mm and rib width of 0.05 mm can effectively improve the wear resistance of superhydrophobic PTFE surface. Even after being rubbed by sandpaper for 6 m, the superhydrophobic PTFE surface with rhombus support rib array structure can still maintain excellent superhydrophobicity, and the icing adhesion of it is only 50% of that of ordinary PTFE surface. The wear-resistant and ice-resistant PTFE surface is expected to be used in ice jet cleaning equipment.