Latest Issue

2024, Volume 41,  Issue 3

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Review
Research progress on coating application and mechanism based on MOF materials
DU Juan, WANG Hongyu, SHI Yuchao, SONG Haipeng
2024, 41(3): 1093-1108. doi: 10.13801/j.cnki.fhclxb.20230814.003
Abstract:
Metal-organic framework (MOF), as a new type of porous crystal material, can be used as nanoparticle and carrier because of its high porosity, diverse structure and controllable chemical structure. Functional coatings prepared based on MOF materials can combine the advantages of MOF and have a wide range of applications, but there are not many papers on the application and mechanism of coatings based on MOF materials. The research status of MOF-based coatings at home and abroad was introduced, focusing on the anti-icing/de-icing applications of MOF-based coatings (superhydrophobic surfaces and smooth liquid-injected porous surfaces (SLIPS)), anti-corrosion applications (MOF materials as nanoparticles and carriers) and antibacterial applications (based on metal ion release, photodynamic therapy (PDT) and photothermal therapy (PTT)), and the anti-icing mechanisms of different coatings (reducing the solidification temperature of water and reducing ice adhesion) were summarized. Antiseptic mechanism (direct physical barrier or formation of compounds to achieve the barrier effect) and antibacterial mechanism (metal ions with weak toxicity to eukaryotic cells achieve antibacterial effect, reactive oxygen species (ROS) are activated under light irradiation to achieve antibacterial effect, and heat is generated by absorbing external light, and antibacterial effect is achieved with increasing temperature). The key challenges, potential applications and development prospects of MOF-based coatings are prospected.
Research progress of cellulose nanofibers based electromagnetic shielding materials
ZHANG Jiancheng, GUO Weijia, SHEN Shunyu, ZHANG Qian, LI Caicai, SUN Qingfeng
2024, 41(3): 1109-1123. doi: 10.13801/j.cnki.fhclxb.20230922.003
Abstract:
Cellulose nanofibers (CNFs), a new type of one-dimensional nanomaterials, have the characteristics of wide sources, high aspect ratio and excellent mechanical properties. A variety of electromagnetic shielding composite materials, such as aerogels, films and sponges, can be prepared by using CNFs as the carrier or reinforcement phase through different methods. In this paper, based on the principle of electromagnetic shielding, the preparation methods and the research progress of different CNFs-based electromagnetic shielding composites are reviewed, and the differences in the structure and performances of different CNFs-based electromagnetic shielding materials are compared. Finally, the research trends and application prospects of CNFs-based electromagnetic shielding functional composites are prospected.
Preparation status of ZrB2, ZrC single-phase powders and ZrB2-ZrC composite powder
REN Jincui, LI Xinyi, WU Yisheng
2024, 41(3): 1124-1140. doi: 10.13801/j.cnki.fhclxb.20231108.002
Abstract:
With the rapid development of science and technology and the increasing technical demand, ultra-high temperature ceramic materials can not only withstand high temperatures but also maintain high strength and high oxidation resistance at high temperatures, making them become the main research trend. ZrB2 and ZrC have become very potential ultra-high temperature structural ceramic materials because of their high melting point, good electrical and thermal conductivity, low density, low thermal expansion coefficient, and high strength and good oxidation resistance at high temperatures. However, ZrB2 and ZrC single-phase powders are difficult to meet the requirements of extreme conditions in aerospace field, so preparing ZrB2-ZrC composite powders has been widely concerned. The synthesis mechanism and preparation methods of ZrB2 and ZrC single-phase powders and ZrB2-ZrC composite powder are reviewed. The limitations of current preparation and application of ZrB2 and ZrC single-phase powders and ZrB2-ZrC composite powder are analyzed, the future research direction is prospected.
Research progress of electrospun P(VDF-TrFE) nanofibers in the field of flexible piezoelectric sensing and energy harvesting
QU Zhan, XIA Guangbo, FANG Jian
2024, 41(3): 1141-1152. doi: 10.13801/j.cnki.fhclxb.20230914.001
Abstract:
Poly(vinylidenefluoride-co-trifluoroethylene) (P(VDF-TrFE)) is a copolymer of polyvinylidene fluoride (PVDF) that exhibits outstanding piezoelectric properties, mechanical properties, and biocompatibility. Therefore, the flexible piezoelectric sensors and energy harvesters based on P(VDF-TrFE) have a promising future in the fields of intelligent textiles, wearable electronic devices and medical and health systems. These devices can convert signals such as tactile, pressure, strain, acoustic waves or even physiological micro-vibrations into electrical signals or low-power electrical energy. This paper aims to provide an in-depth analysis of the mechanism of P(VDF-TrFE) piezoelectric properties, summarize various strategies to enhance the piezoelectricity of electrostatically spun P(VDF-TrFE) nanofibers, and provide a comprehensive overview of the applications of P(VDF-TrFE)-based flexible piezoelectric sensing and energy harvesting. Specifically, research advances in the areas of pressure and tactile sensing, acoustic sensing, biological tissue sensing, physiological micro-vibration sensing, and energy harvesting are summarized. Finally, the emerging application scenarios of electrospun piezoelectric polymer nanofibers are illustrated, the current challenges and future prospects in this field are discussed.
Application of biomass chitosan-based composites for CO2 separation and capture and resource utilization
FENG Ying, YU Hanzhe, ZHANG Hong, LI Kexin, DONG Xin, ZHANG Jianwei
2024, 41(3): 1153-1165. doi: 10.13801/j.cnki.fhclxb.20230913.001
Abstract:
There is an urgent need to explore new treatment technologies and biomass materials to mitigate the growing ecological problems of global warming, sea level rise and climate degradation caused by excessive carbon dioxide emissions. This paper reviews the research progress of biomass chitosan in CO2 separation, capture and resource utilization; details the mechanism of CO2 separation by chitosan membranes and methods to improve membrane separation performance; summarizes the methods to enhance the CO2 capture performance of chitosan-based activated carbon; and summarizes the research on the conversion of CO2 into value-added products such as carbonate, methane and olefin by chitosan-based catalysts. Finally, the future development trend of biomass chitosan in the process of helping to achieve the "double carbon" strategic goal is presented.
Application progress of natural clays in proton exchange membrane
WANG Bei, LING Zhiwei, ZHOU Yilin, FU Xudong, ZHANG Rong, HU Shengfei, LI Xiao, LIU Qingting
2024, 41(3): 1166-1178. doi: 10.13801/j.cnki.fhclxb.20231031.003
Abstract:
As a key component of polymer electrolyte fuel cells, the proton exchange membrane (PEM) directly impacts cell performance. Expanding its operational temperature and humidity range is advantageous for simplifying fuel cell water and thermal management designs, thereby promoting miniaturization and cost reduction. In recent years, the development of polymer composite membranes based on natural clay has emerged as a crucial avenue for enhancing traditional PEM performance and broadening its applicability across varying environmental conditions. Natural clay minerals predominantly consist of hydrated layered silicate compounds, characterized by unique pore and layer structures at the nanoscale, endowing them with substantial specific surface area and surface effects. The abundance of hydroxyl groups on their surfaces and interlayers not only enhances the mechanical strength of composite membranes but also immobilizes mass transport media. Consequently, these materials facili-tate the creation of novel proton-conductive pathways within the composite membrane, thereby elevating membrane performance. We comprehensively review, from a nanoscale perspective, various categories of clay minerals, elucidating their structural and performance attributes. Furthermore, we provide a comprehensive summary and future prospects of research advancements in natural clay mineral-composite proton exchange membranes.
Performance optimization and deterioration mechanism of fiber reinforced epoxy/vinyl resin composite materials: A review
CAO Yinlong, YU Zhenqi, FENG Peng, LI Rong, ZHANG Peng, ZHANG Shaojie, BAO Jiuwen
2024, 41(3): 1179-1191. doi: 10.13801/j.cnki.fhclxb.20230914.002
Abstract:
Fiber reinforced polymer (FRP) composite has great potential in infrastructure construction due to the advantages of light weight and high strength, corrosion resistance and high economic benefit. However, the performance of FRP composite will decrease by more than 50% after long-term service in complex environment, which limits its application in engineering. In the paper, the enhancement methods of different FRP composites components are reviewed. The evolution law of FRP composites on long-term properties under thermal oxygen, ultraviolet and corrosive media environment are revealed, and the deterioration mechanism of FRP composites in complex environment is elucidated by the analysis of chemical structure and microstructure. In addition, the long-term performance prediction model of FRP composites under complex environments is summarized, which can provide theoretical basis for ensuring the long-term performance of FRP composites in complex environment and promote its application in practical engineering.
Research progress of decommissioned wind power blade resource utilization technology
ZHANG Xiaolin, YANG Menghao, CAO Jing, HE Jun, GAO Limin, LI Xin
2024, 41(3): 1192-1203. doi: 10.13801/j.cnki.fhclxb.20231019.001
Abstract:
Wind power, because of its clean, efficient, renewable and other advantages, has become an important part of China's strategic action plan for energy development, and China has become the world's largest installed wind power capacity. With the arrival of the wind turbine retirement tide, the retired wind turbine blade (RWTB) has become a large solid waste material that China urgently needs to solve. Wind turbine blades are mainly prepared from glass fibre/carbon fibre/plant fibre reinforced composites, and the traditional treatment menthods are mainly landfill and incineration, which not only results in a large amount of wasted resources, but also leads to environmental pollution. The resourceful and high-value utilisation of decommissioned wind turbine blades has become a research hotspot of great concern to the country. This paper briefly describes the scale of installed wind power and the development scale of RWTB at home and abroad, overviews the existing recycling technologies (mechanical recycling, pyrolytic recycling, chemical recycling) of wind turbine blades, overviews the current status of recycling application of RWTB, summarises and analyses the strengths and weaknesses of various types of recycling technologies and the current status of their application. Analysed the prospect of RWTB recycling technology and application, put forward the "multi-method" gradient use and the "high efficiency and standardised full use" without secondary pollution are important research direction of RWTB recycling technology.
Research progress on crystal structures and properties of superlattice La-Mg/Y-Ni composite hydrogen storage alloys
ZHANG Xiaojie, TIAN Xiao, ZHANG Ying, HAN Jiale, YANG Yanchun, TA Na
2024, 41(3): 1204-1214. doi: 10.13801/j.cnki.fhclxb.20231017.001
Abstract:
The La-Mg/Y-Ni composite hydrogen storage alloys with superlattice structure have the advantages of large discharge capacity, high energy density and low cost, and are important hydrogen energy storage and conversion material. At present, they are mainly used as the negative material of nickel-metal hydride batteries and anode catalyst of direct borohydride fuel cell. Superlattice La-Mg-Ni composite alloy was originally developed on the basis of La-Ni based hydrogen storage alloy by replacing La with partial Mg. Due to the low melting point and boiling point of Mg and its volatility, La-Mg-Ni alloy is difficult to be prepared by conventional melting method. At the same time, Mg in the alloy is easy to corrode and oxidize in the alkaline electrolyte, resulting in poor cycling stability of the La-Mg-Ni alloy. In order to overcome the difficulties in the preparation and the poor cycle stability of La-Mg-Ni composite alloy, the researchers also developed La-Y-Ni alloy on the basis of La-Ni based hydrogen storage alloy by replacing La with partial Y. La-Mg-Ni and La-Y-Ni alloys have very similar superlattice structures, and both can show good hydrogen storage properties. It can be seen that they belong to the same class of new superlattice structure hydrogen storage alloys. The research achievements of La-Mg/Y-Ni composite hydrogen storage alloys in the past 20 years are reviewed in this paper. The crystal structure and structure evolution of superlattice La-Mg/Y-Ni hydrogen storage alloys are introduced in this paper. Then, the effects of Mg element and Y element partial substitution of La element on the structure and properties of La-Mg/Y-Ni composite alloy are analyzed. At the same time, the effect of phase structures on the properties of La-Mg/Y-Ni composite alloys are discussed. Finally, the future challenges and development directions of superlattice La-Mg/Y-Ni composite hydrogen storage alloys are pointed out.
A review on reinforcing and toughening methods of geopolymers
SHA Dong, WANG Baomin, PAN Baofeng, BAO Chao
2024, 41(3): 1215-1225. doi: 10.13801/j.cnki.fhclxb.20230911.003
Abstract:
Due to the excellent mechanical properties, good durability, and low carbon and environmental friendly synthetic characteristics, geopolymers are considered as the most promising new cementitious materials to replace portland cement. Unfortunately, there are some defects in geopolymers: On the one hand, coal-based solid wastes with low calcium content such as fly ash and coal gangue can only obtain high strength cured at a high temperature, while the strength of geopolymers prepared at room temperature is low; On the other hand, geopolymers have disadvantages such as high brittleness and low toughness, which seriously restricts the large-scale application of geopolymers. In this study, the effects of mechanochemical effect, compounding of silicon, aluminum and calcium substances, fiber and organic matter modifications on the mechanical properties of geopolymers were reviewed, and the mechanisms of strengthening and toughening were also summarized. Finally, some suggestions were made for related studies that needs to be carried out in depth in the future.
Resin Polymer Composite
Preparation and properties of 4D printed magneto responsive shape memory epoxy resin-based composites
DENG Pan, WU Zhi, SUN Jiye, LU Linjiao, SHAN Yilian, DU Jianke, ZHANG Minghua
2024, 41(3): 1226-1234. doi: 10.13801/j.cnki.fhclxb.20230714.002
Abstract:
ACB-Ni/EP51 composites were prepared by using direct-write 3D printer with ink that was blended from epoxy resin (EP51) as the matrix, acetylene black (ACB) and nickel powder (Ni) as fillers, and polyether polyol (PPG) as toughening agent. Rheological properties and printability of ink were characterized by rheometer and direct-write 3D printer, mechanical properties, microscopic morphology, thermal properties, and shape memory properties of the material were characterized by universal tensile testing machine (UTM), scanning electron microscope (SEM), dynamic thermomechanical analyzer (DMA), and differential scanning calorimeter (DSC). The effects of fillers on properties of the ink and material were investigated. The results show that the ink can be printed well when the ACB content reaches 12wt%. Clogging of the printer nozzle causes discontinuous and uneven printing when Ni content reaches 16wt%. The toughened structure of the "island" formed after solidification significantly improves the tensile strength of the material (above 60 MPa). As Ni content increases, the effect of Ni on tensile strength changes from promoting to weakening. The shape fixation rate (Rf) decreases from 99.4% to 94.2% when Ni content increases 6wt% increases to 14wt%. Under the action of a 300 kHz alternating magnetic field, the shape recovery occurs, and an increase in Ni content results in higher shape recovery rate (Rr) and recovery rate, Rr increases from 94.8% to 99.1%, and the recovery time shortens from 39 s to 17 s. The ACB-Ni/EP51 composites exhibits excellent shape memory performance and has promising application prospects in areas such as deployable structures in space, actuators, and 4D printing.
Study on compressive strength and thermal conductivity of interlayer reinforced and stiffened CFRP composites with CNT films
ZHU Zaibin, LING Hui, YANG Xiaoping, LI Gang, WANG Chao
2024, 41(3): 1235-1248. doi: 10.13801/j.cnki.fhclxb.20230814.005
Abstract:
In recent years, the structure-function integrated carbon fiber reinforced plastic (CFRP) composites have attracted extensive attention, and the interlayer reinforcing and stiffening based on carbon nanotube (CNT) films with high strength, high modulus and high thermal conductivity provided an innovative idea. In this paper, the stretched CNT films (S-CNTF), epoxided CNT films (E-CNTF) and stretched-epoxided CNT films (S-E-CNTF) were prepared by wet stretching and epoxidation reaction based on pristine CNT films (P-CNTF), and used for interlayer reinforcing and stiffening CFRP composites (CFRP/S-CNTF, CFRP/E-CNTF and CFRP/S-E-CNTF), respectively. The physicochemical characteristics and tensile properties of CNT films were analyzed, and the effects of S-E-CNTF on longitudinal compressive strength and failure mechanism of composites were studied by combining Jumahat's combined model and experimental verification. Meanwhile, the in-plane thermal conductivity and corresponding mechanism of composites were discussed. In contrast with P-CNTF, the CNTs in S-E-CNTF present highly oriented bunching morphology and the surface chemical activity of S-E-CNTF is observably improved, so that the tensile strength and modulus of S-E-CNTF are enhanced to 116 MPa and 6.3 GPa, respectively. In comparison with CFRP, the in-plane shear modulus and interlaminar shear strength of CFRP/S-E-CNTF are increased by 28.3% and 34.2%, respectively, implying that the S-E-CNTF can effectively inhibit delamination and enhance resistance of shear deformation of CFRP. The model prediction also shows that the theoretically elastic and plastic compressive stress of CFRP/S-E-CNTF are increased by 30.7% and 32.3%, respectively, which is in accord with experimental values. Meanwhile, based on the three-dimensional thermal conductivity network constructed by S-E-CNTF in the interlaminar region of CFRP, the in-plane thermal conductivity of CFRP/S-E-CNTF is improved to 7.8 W/(m·K).
Preparation and flame retardancy of thermoplastic polyester elastomer composites
LIU Tianming, ZHAO Dong, SHEN Yucai, JIANG Guodong, WANG Tingwei
2024, 41(3): 1249-1258. doi: 10.13801/j.cnki.fhclxb.20230724.004
Abstract:
Thermoplastic polyester elastomer (TPEE) is extremely flammable, which seriously hinders its application in the fields of electronics and electrical, wire sheath, charging station, etc. TPEE composites with high flame retardancy were prepared by adding aluminum diethylphosphinate (AlPi) and melamine polyphosphate (MPP) flame retardant into TPEE matrix through internal mixing and hot pressing process. The flame retardancy of the TPEE composites was studied by limiting oxygen index (LOI), vertical burning (UL-94) and cone calorimeter (CONE) tests. The results show that AlPi combined with MPP can achieve high-efficiency flame retardancy of TPEE composites. In addition, the TPEE composite with 22wt%AlPi and MPP passed the UL-94 V-0 rating and its LOI value increase from 19.3% to 31.5%, accompanied with 27.6% reduction in the total heat release and 64.8% reduction of the peak heat release rate compared to pure TPEE. The thermal stabilities, mechanical properties, and electrical properties of the TPEE composites, as well as the microscopic morphology of the composites before and after ablation were studied by thermogravimetric analyzer (TGA), SEM, universal testing machine and electrical insulation test. The results indicate that the flame retardant mechanism of the composite flame retardant system is the barrier action of intumescent char layer in the condense phase. The composite flame retardant system can promote the decomposition of TPEE into carbon. The mechanical properties, electrical insulation properties and microtopography tests show that the combination of AlPi and MPP can improve the electrical insulation performance, but reduce the mechanical properties of TPEE composites due to their poor compatibility with TPEE matrix.
Effect of vulcanization system on thermal aging property of silicone rubber
FAN Zaiqian, XIAN Richang, BIAN Jihui, GE Wangquan, XING Yawen, SUN Fengrui
2024, 41(3): 1259-1269. doi: 10.13801/j.cnki.fhclxb.20230814.004
Abstract:
In order to explore the effects of different vulcanization systems on the thermal aging properties of sili-cone rubber used for enhanced insulation of cable accessories, silicone rubber was used for enhanced insulation of 35 kV cable accessories as the research object, and peroxide and hydrosilane addition vulcanization systems were used to produce vulcanized silicone rubber samples and carry out thermal aging tests to compare and analyze the mechanical and electrical properties of the rubber. In the early stage of thermal aging, the oxidative cross-linking reaction of molecular side chains and the re-cross-linking reaction between molecular chains occurred in both sili-cone rubber vulcanization systems, and the cross-linking degree increased. In the later stage of thermal aging, the cross-linking system structure and molecular chain were destroyed, and the cross-linking degree decreased. The research and test results show that the tensile strength and elongation at break of silicone rubber samples gradually decrease with the increase of thermal aging time, the conductivity decreases first and then increases with the increase of temperature, the relative dielectric constant increases gradually and decreases with the increase of temperature, the tangent of dielectric loss angle increases gradually and increases with the increase of temperature, and the breakdown field strength increases first and then decreases. The silicone rubber under the hydrosilane addition vulcanization system has always maintained high crosslinking degree and has better mechanical and electrical properties after thermal aging, while the silicone rubber under the peroxide vulcanization system produces strong acidic by-products during vulcanization and produces strong polar groups after thermal aging, resulting in the deterioration of the thermal aging performance of the silicone rubber.
Evaluation of electrical aging life of nano SiO2/PP composites
GAO Junguo, ZHANG Guangwei, LIU Yanli, JU Huicheng, LIU Liwei, LIU Xiongjun, HAN Xiao
2024, 41(3): 1270-1280. doi: 10.13801/j.cnki.fhclxb.20230818.002
Abstract:
The electrical aging life of polypropylene (PP) insulation, a new environmentally friendly material, and its nano-SiO2 composites were investigated to provide theoretical support for the reliability of PP-insulated cables in later applications. Based on the electric aging life formula-inverse power method, the life model parameters of PP insulation and SiO2/PP composites were estimated by constant voltage accelerated aging test, and then the reliabi-lity of life index n was evaluated by stepwise accelerated aging test. The SiO2/PP composites were also structurally characterized and performance tested. The results show that the lifetime index n of SiO2/PP6 is 14.61, which is enhanced by 16.51% compared with that of PP6 of 12.54. It is found in the experimental stage that the doping of SiO2 has a significant effect on the enhancement of PP6's time to failure at lower aging field strengths, and it is predicted that the long-term electrical aging lifetime of SiO2/PP6 is more than five times that of PP6 below the aging field strength of 25 kV·mm−1. Meanwhile, the doping of nano-SiO2 reduced the industrial frequency dielectric loss factor and lowered the loss peak height of PP insulation. Based on the electrical aging cavity theory, it is proposed that SiO2 enhances the electrical aging life of PP insulation by limiting the chain segment breakage by consuming hot electron energy.
Effect of basalt modified by coupling agents with different molecular structures on foaming behavior and properties of basalt/polypropylene composites
ZHU Nenggui, LI Shengnan, ZENG Xiangbu, SHEN Chao, JIANG Tuanhui, GONG Wei, HE Li, HUANG Anrong
2024, 41(3): 1281-1289. doi: 10.13801/j.cnki.fhclxb.20230707.002
Abstract:
In this paper, basalt fiber (BF) was used as reinforcement phase and polypropylene (PP) as the matrix, BF/PP foam composites were prepared using a chemical foaming secondary mold opening process. The thermal properties, rheological properties, foaming behavior and mechanical properties of BF/PP foam composites modified with different sub structure coupling agents were studied using DSC, SEM and other characterization techniques. The results show that after modifying BF with different molecular structure coupling agents, the crystallization and rheological properties of the composite improve, the crystallinity increase, and the melt viscoelasticity improve. When KH-550 is used to modify BF, the foaming quality of BF/PP foamed composites is the best, with a foam cell size of 84.52 μm. Cell density is 2.45×105 cells/cm3. After BF is modified by coupling agent, the flexural strength, flexural modulus, and tensile strength of the foam composite are improved compared to those of the unmodified BF; When modifying BF with KH-792, the maximum flexural strength, flexural modulus, and tensile strength are 33.4 MPa, 1919 MPa, and 21.4 MPa, respectively. This study provides a theoretical reference for the development and industrial application of BF/PP foam composite materials.
Functional Composite
Optimization of broadband sound absorption performance of honeycomb sandwich sound liner
LUO Liang, BAI Heyu, YE Zhuoran, GU Yizhuo
2024, 41(3): 1290-1299. doi: 10.13801/j.cnki.fhclxb.20230817.005
Abstract:
In view of the wide frequency noise characteristics of turbofan engine with large bypass ratio at present, traditional single-degree-of-freedom honeycomb sandwich acoustic lining material was optimized to improve its sound absorption performance. Under the premise of keeping the basic form of single-degree-of-freedom honeycomb structure of sound liner unchanged, in order to broaden the sound absorption spectrum and reach two or more characteristic frequencies, carbon nanotube film was compounded at a specific position inside the single-layer honeycomb core. At the same time, in order to improve the sound absorption effect, metal wire mesh and flexible porous materials were introduced between perforated plate and honeycomb core, and they were assembled through a rapid process. The influences of placement position and parameters of the introduced material on the sound absorption performance of the sound absorption composite were also investigated. The experimental results show that the structure with the best sound absorption performance is the introduction of 37 μm hole diameter wire mesh placed behind the porous panel, the placement of 15 mm thick melamine sponge between the porous panel and the honeycomb, and the placement of carbon nanotube film with a porosity of 2% and 4% in the middle of the honeycomb sandwich structure. The sound liner prepared based on this result has excellent sound absorption performance, and shows good sound absorption performance in the range of 800 Hz to 4500 Hz. The peak sound absorption coefficients of the two characteristic frequencies reach 0.98 and 0.99, respectively, and the average sound absorption coefficient reaches 0.89, which is 61.8% higher than that before optimization. At the same time, the half-peak width can fully cover the frequency range of 800 Hz to 4500 Hz tested, which indicates good broadband noise reduction characteristics.
Preparation of GO/epoxy acrylic coating and application in corrosion resistance of concrete to deicing salt
SONG Lifang, ZHAO Like, LI Kaiyuan, XIA Huiyun, NIU Yanhui
2024, 41(3): 1300-1315. doi: 10.13801/j.cnki.fhclxb.20230714.004
Abstract:
AGO/WEP and KGO/WEP anti-corrosion coating was prepared, using epoxy resin E-44 and three acrylic monomers as raw materials, modified by different dosages of graphene oxide (KH560/GO (KGO), A151/GO (AGO)) under in-situ polymerization method. The results show that the addition of KGO or AGO can both improve the thermal performance of the composite coating. The comprehensive performance of 0.05wt%KGO/WEP is better, the pencil hardness of the composite coating is 5H, the impact strength is more than 50 cm, the bonding strength is 1.79 MPa, the water absorption rate is 1.06%, the contact angle is 78.05°, the color difference after 1000 h UV aging is 0.75, the gloss is maintained well at 9.7, the coating morphology is maintained well after 240 h of chemical resistance, and the chloride ion permeability of the coating is 0.34×10−3 mg/(cm2·d). The results show that the 0.05wt%KGO/WEP coating has good comprehensive performance and a maximum bond strength is 1.91 MPa after 40 salt freeze cycles. The mass growth rate is 1.46%, the chloride ion flux at 6 h is 532 C, the compressive strength loss is 18.2%. The composite coating can effectively improve the corrosion resistance of snow melting salt on the surface of concrete substrate, and has important research significance for improving the maintenance level of roads.
Study on preparation and absorption properties of ZnO-graphene-TPU/PLA composites
WU Haihua, FU Wenxin, LIU Shaokang, CHAO Bin, BAO Yuntian
2024, 41(3): 1316-1326. doi: 10.13801/j.cnki.fhclxb.20230627.003
Abstract:
Developing light-weight and high-efficiency absorbing composite materials is one of the important ways to solve the electromagnetic pollution. In this paper, ZnO-graphene (GR)/polylactic acid (PLA)/thermoplastic polyurethane (TPU) composite materials were prepared by a two-step method and the phase structure, micromorphology and electromagnetic characteristics of the composite were characterized by XRD, Raman spectroscopy, SEM and vector network analyzer. The effects of different combinations of ZnO/GR on the microwave absorbing properties of the composites were studied, and the synergistic mechanism was revealed. The results show that with the increase of the content of ZnO, the microwave absorbing effect increases at first and then decreases. Proper amount of ZnO dispersed in the matrix increases the defects of the composites enriching the heterogeneous interface, enhancing the interface polarization and dipolarization, and improving the microwave absorbing properties of the composites. When the content of ZnO is 2wt% , at 5.6 mm thickness, the minimum reflection loss is −49.2 dB and the effective absorption bandwidth is 2.0 GHz meaning the best absorption efficiency. The excellent absorbing effect is attributed to the good impedance matching and the synergy among the interface polarization loss, the dipolarization loss and the conductivity loss. In addition, the preparation process of ZnO-GR/PLA/TPU composite is simple and environment-friendly, and the component of absorbing agent can be adjusted which is expected to be used in the manufacturing of complex absorption structures.
Performance and mechanism of U(VI) removal from solution by pomegranate peel carbon supported CaTiO3 composites
GONG Yi, LI Xiaoyan, ZHANG Yishuo, LI Kun, LI Mingzhe, CAO Xiaogang, DU Yanjun, LIU Bo
2024, 41(3): 1327-1337. doi: 10.13801/j.cnki.fhclxb.20230817.004
Abstract:
In order to achieve the goal of green and efficient energy utilization, how to deal with uranium-containing waste generated during the development of nuclear energy has become an increasingly prominent environmental problem. The CaTiO3 materials were initially prepared using the solvent-thermal method. Subsequently, the carbon material was synthesized by grinding a mixture of CaTiO3 and pomegranate peel carbon material, resulting in the formation of carbon-loaded CaTiO3 (C@CaTiO3). Modern characterization techniques were employed to analyze the morphological and compositional changes of C@CaTiO3 before and after its reaction with U(VI). The performance of the material in removing uranium from the solution was evaluated using a static experimental method. The research findings revealed that, under the conditions of pH=3.5, an initial concentration of U(VI) of 25 mg·L−1, reaction time of 40 min, and temperature of 25℃, the material exhibited a U(VI) removal rate of 96.26% with a corresponding removal capacity of 119.21 mg·g−1. The reaction mechanism between C@CaTiO3 and U(VI) was investigated using adsorption kinetics models, isothermal adsorption models, and thermodynamic models. The results demonstrate that the adsorption process of U(VI) by C@CaTiO3 is a spontaneous endothermic reaction. The removal of U(VI) from the solution using C@CaTiO3 involved both adsorption and reduction, with physical and chemical adsorption coexisting and surface monolayer chemical adsorption being the predominant mechanism. Photocatalytic reduction played a major role in the reduction process.
Photoelectrochemical cathodic protection performance of two-dimensional Ti3C2-modified WO3/SrTiO3 heterojunction composites
SU Xinyue, WANG Jiansheng, ZHAO Yingna, QING Da, ZENG Xiongfeng
2024, 41(3): 1338-1346. doi: 10.13801/j.cnki.fhclxb.20230705.001
Abstract:
The introduction of second-phase materials to construct heterojunctions and the addition of co-catalysts can effectively improve the photoelectrochemical performance of semiconductor materials. In this study, Ti3C2-WO3/SrTiO3 composites were designed and prepared to protect 304 stainless steel (304 SS) by photochemical cathodic protection technology in simulated sunlight environment. The results show that the photoelectrochemical cathodic protection performance of Ti3C2-WO3/SrTiO3 composites is significantly enhanced. Coupling 304 SS with Ti3C2-WO3/SrTiO3 composites transfers the potential of 304 SS from −0.13 V to −0.42 V, and the ternary composites produce a photocurrent density 7 times higher than SrTiO3 alone. The heterojunction electric field formed at the WO3/SrTiO3 interface and the addition of co-catalyst Ti3C2 synergistically improve the separation efficiency of photogenerated electrons and holes, and improve the photoelectrochemical cathodic protection performance.
Construction of highly hydrophobic nanocellulose-chitosan/bentonite aerogel and its application of efficient oil-water separation
XU Shiqi, ZHOU Zhou, TANG Rui, JIANG Luying, WANG Junhui, JIN Xuequn, ZHANG Jingwei, LIAO Dankui, TONG Zhangfa, ZHANG Hanbing
2024, 41(3): 1347-1355. doi: 10.13801/j.cnki.fhclxb.20230912.003
Abstract:
Due to the high porosity and high absorption characteristics, aerogel has been a promising candidate material in the field of oily wastewater treatment. However, the reported aerogels were still suffering from insufficient mechanical strength, complicated fabrication process and high preparation cost, which limited the application of aerogels in the field of oil-water separation. Bentonite (BT) has the characteristics of low price, abundant source and excellent mechanical properties, which can effectively improve the mechanical properties of aerogels. In this paper, hydrophobic nanocellulose-chitosan/exfoliated bentonite aerogels (CNC/BTex) were synthesized by introducing exfoliated bentonite (BTex) onto a cross-linked network of carboxycellulose nanofibres (CNF-C) and chitosan (CS) by a simple freeze-drying and ambient temperature impregnation method. The prepared CNC/BTex aerogel exhibited excellent hydrophobic properties (water contact angle 133°), recovered deformation within 5 s after extrusion and showed good mechanical properties. The adsorption capacities for different oils (hexane, cyclohexane, dichloromethane, cooking oil and engine oil) ranged from 18.48-40.20 g·g−1. Using dichloromethane and cyclohexane as the main research objects, the oil adsorption performance remained stable (90% of the original adsorption capacity) after five cycles of use. In summary, the present work provides a reference for the preparation of low-cost and high-performance adsorbent materials for oil-water separation.
Effect of ion doping on microwave absorbing properties of sodium alginate/SiO2 aerogels
LI Jun, YU Mingxun, LIU Yao, LIN Long, GOU Wenqi, ZHOU Shuai
2024, 41(3): 1356-1366. doi: 10.13801/j.cnki.fhclxb.20230629.001
Abstract:
With the intensification of electromagnetic pollution, absorbing materials have attracted the attention of researchers, and airgel has the potential to become an ideal absorbing material due to its light weight and porous characteristics. PVA/SiO2 nanofibers were prepared by electrospinning from polyvinyl alcohol (PVA) and ethyl orthosilicate (TEOS), the flexible SiO2 nanofibers were homogenized in sodium alginate (SA) solution and freezedried to obtain SA/SiO2 aerogels. SA/SiO2/AlBSi and SA/SiO2/FeCl3 aerogels were prepared by introducing AlBSi and FeCl3 as dopants, respectively. Microwave absorbing properties of three kinds of aerogels were analyzed. The results show that there are small particles on the surface of SiO2 nanofibers, which are the SA/SiO2 aerogel doped by FeCl3. This granular structure produces multiple reflection and scattering, interface polarization, which improves the dielectric loss performance of aerogels. After adding FeCl3, the imaginary part of the magnetic loss of the aerogel increases, which improves the magnetic loss performance of the aerogel. Thus, the overall wave absorption performance of aerogel is improved. When the thickness is 3 mm, its maximum absorption peak is –23.85 dB, reaching 14.42 GHz. It has an effective absorption bandwidth of 1.3 GHz (13.82-15.12 GHz). It is a light material with good wave absorption performance.
Piezo-photocatalytic property of PbTi0.85Ni0.15O3/TiO2 nanorod array composite materials
ZHOU Xiaoju, QIAN Jun, HU Zhenglong, REN Yiming
2024, 41(3): 1367-1377. doi: 10.13801/j.cnki.fhclxb.20230630.001
Abstract:
The built-in electric field induced by piezoelectric materials has been proven to be one of the most effective strategies for regulating charge transfer pathways and suppressing carrier recombination. PbTi0.85Ni0.15O3/TiO2 nanorod arrays compsite were fabricated via a two-step process comprising hydrothermal and sol-gel methods. By degrading organic dyes, composite materials exhibit excellent piezo-photocatalytic performance. After 30 minutes, the piezo-photocatalytic degradation rate of methylene blue (MB) by PbTi0.85Ni0.15O3/TiO2 reached 97.3%, with a degradation reaction rate of 0.1215 min–1, which is 3.3 times of the photocatalytic degradation rate (0.0372 min–1) and 5.7 times of the piezoelectric catalytic degradation rate (0.0211 min–1). After doping Ni, the band gap decreases, the carrier concentration increases, the lattice distortion increases, and the piezo-photocatalytic performance enhances. The results of sacrificial agent addition experiments and electron spin resonance spectroscopy (ESR) experiments indicate that •O2 and •OH are the main active spices in piezo-photocatalytic degradation. After doping Ni, the band gap decreases, the carrier concentration increases, and the lattice distortion increases, resulting in superior piezo-photocatalytic performance of PbTi0.85Ni0.15O3/TiO2 compared to PbTiO3/TiO2. In addition, the degradation of different dyes by PbTi0.85Ni0.15O3/TiO2 and the degradation rate after 5 cycles indicate that the composite material has good piezo-photocatalytic degradation property for various dyes and good stability. According to the energy band arrangement, it is proposed that the tilting and bending of the energy band caused by piezoelectric polarization can promote the separation of photogenerated carriers, so that dye degradation has excellent piezoelectric photocatalytic performance.
β-cyclodextrin modified magnetic palm fiber biochar for highly efficient Pb(II) removal from water
CUI Can, NIU Jiaojiao, YANG Lian, ZHOU Lingyun, WANG Huanjiang, XIE Yadian
2024, 41(3): 1378-1390. doi: 10.13801/j.cnki.fhclxb.20230706.002
Abstract:
In order to solve the water contamination arises from heavy metal Pb(II), β-cyclodextrin modified magnetic palm fiber biochar (β-CD@PFMBC) was prepared with palm fiber as raw material by chemical coprecipitation method for efficient removal of Pb(II) from aqueous solution. The structure and morphology of the material were characterized by FTIR, XRD, BET, SEM, Raman and VSM. The adsorption properties of Pb(II) were analyzed through single factor experiment. The adsorption mechanism and recycling of Pb(II) were also explored. The results show that the specific surface area and the number of surface functional groups of β-CD@PFMBC increased compared with the pristine biochar. The adsorption process of Pb(II) can be better described by both the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model, which indicates that the adsorption process is chemical adsorption and monolayer adsorption. According to the Langmuir isotherm model, the maximum theoretical adsorption capacity of β-CD@PFMBC at 303 K is 625.49 mg∙g–1, which is significantly higher than that of the pristine biochar. Thermodynamic studies show that the adsorption is a spontaneous endothermic process. The oxygen-containing groups on the surface of β-CD@PFMBC produce surface complexation and electrostatic interaction with Pb(II). The removal ration remains above 79% after five cycles of adsorption-desorption. It can be expected that β-CD@PFMBC will be of potential application in removing of Pb(II) from aqueous solution.
Effect of Cr(VI) on photocatalytic of xanthate and synergistic mechanism
ZHANG Xueqiao, ZHONG Xiaojuan, TANG Shuang, JIANG Liping, WEI Yufan, XIAO Li
2024, 41(3): 1391-1401. doi: 10.13801/j.cnki.fhclxb.20230814.001
Abstract:
In order to further study the effect of Cr(VI) on the photodegradation of xanthate and its synergistic mechanism in the co-existing system of xanthate and Cr(VI), the photocatalyst of coal gangue/bismuth vanadate (CG/BiVO4) was used, xanthate and Cr(VI) coexisting systems were studied by photocatalytic activity test, UV, FTIR, ion chromatography and quenching experiments, the photooxidation of xanthate and photoreduction of Cr(VI) and their synergistic mechanism were explored. The results show that there is a significant synergistic effect between the photo-oxidation of xanthate and photo-reduction of Cr(VI) in the co-existence system of xanthate and Cr(VI). Then, at the xanthate of 25 mg/L and the pH value of 7, with the dosage of catalyst being 1. 5 g/L, at the Cr(VI) of 2.0 mg/L, the removal rate of xanthate and Cr(VI) by CG/BiVO4 are the best during a period of 480 min, reaching 98.81% and 88.80% respectively. The predicted degradation rate of xanthate is 94.79% by response surface methodology, lower 3.82% than the actual degradation rate, which indicates that the model can be used to predict the degradation of xanthate in the co-existing system. In the co-existing system, the vibration of C=S is changed first, followed by C—O—C, S—H, S—C—S, butyl, and the intermediate product peroxy xanthate (ROCSSO) is formed after the visible light illumination 3 h , the highest conversion of sulfur is reached 97.94% after the visible light illumination 7 h. The synergistic mechanism analysis shows that the photogenerated e are rapidly captured in the photo-reduction of Cr(VI) and photogenerated h+ are consumed by xanthate photodegradation. The photogenic electron and hole pairs are consumed, on the one hand, due to the inhibition of photogenerated electrons and holes recombination, the lifetime of photogenerated electron and hole pairs are prolonged, on the other hand, the rapid consumption of photogenerated electron-hole pairs accelerates the conversion of light energy to chemical energy, generating a large number of photogenerated electron-hole pairs, therefor promoting the synergistic removal of xanthate and Cr(VI) .
Civil Construction Composite
Effect of nano-SiO2 and polypropylene fibers on the mechanical properties and microscopic properties of all coal gangue aggregate concrete
YAO Xianhua, GUO Xiaoning, HAN Ruicong, GUAN Junfeng, LI Huan
2024, 41(3): 1402-1419. doi: 10.13801/j.cnki.fhclxb.20230714.005
Abstract:
Coal gangue as industrial solid waste, replacing all aggregates to produce concrete, is an effective way to reuse coal gangue. In this paper, all the coarse and fine aggregates of concrete were replaced by crushed coal gangue aggregate, and modified by different amounts of nano-SiO2 and polypropylene fiber (PPF). Based on the combination of macro mechanics and micro analysis, the effects of the single and combined action of nano-SiO2 and PPF on the mechanical properties and microstructure of concrete were studied. The results show that the performance of concrete is the best when the mixture of nano-SiO2 and PPF is 1.5wt% and 0.6 kg·m−3, respectively. Compared with the control group, the compressive strength, flexural strength and splitting strength of the concrete at 7 days increase by 21.8%, 43.5% and 44.4%, respectively. Besides, the compressive strength, flexural strength and splitting strength at 28 days increase by 20%, 44.9% and 43.6%, respectively. The microstructure analysis shows that the porosity of coal gangue concrete decreases, the hydration process is accelerated, the fractal dimension of large holes of the concrete increases from 2.9975 to 2.9990, while that of small holes decreases from 2.9852 to 2.9827, the fractal dimension of small holes decreases, and the fractal dimension of large holes increases, so that the stronger the space filling capacity, the fewer internal pores.
Experimental and theoretical study on flexural behavior of precast UHPC-RAC composite beams
QIN Chaogang, WU Tao, LIU Boquan, WANG Bo, LI Yu
2024, 41(3): 1420-1435. doi: 10.13801/j.cnki.fhclxb.20230704.001
Abstract:
Ultra-high performance concrete (UHPC) and recycled aggregate concrete (RAC), with a low carbon footprint, belong to the "Low Carbon Concrete". A portion of RAC on the tensile side or side wall of the RAC beam was replaced with UHPC to form a "green and low carbon" UHPC-RAC composite section to improve mechanical pro-perties. The precast UHPC-RAC composite beam was fabricated by precast technology. The influences of tensile UHPC thickness, roughness of UHPC-RAC joint surface and UHPC height of side wall on failure mechanism, bearing capacity, deformation and initial stiffness of precast UHPC-RAC composite beams were analyzed by four-point flexural tests, then the calculation formula of bearing capacity were proposed. The results show that, comparing precast UHPC-RAC composite beams with RAC beams, the UHPC-RAC bonding surface traversed by the stirrups with the increase of UHPC thickness on the tensile side limits the peeling off of UHPC after cracking. The increasing roughness of the interface further retards the extension of horizontal cracks and improves the initial stiffness about 16.6%. With the failure of steel fiber pulling out in the UHPC on the tensile side, the load-displacement curves decrease obviously. The precast composite beams still have a high residual strength when the compression concrete is crushed. Compared with RAC beams, the cracking load and ultimate load of precast UHPC-RAC composite beams are increased by 63.1% and 22.9%, respectively, and the section flexural stiffness and initial stiffness are signifi-cantly improved. In the composite section, reinforcement, UHPC and RAC work collaboratively, and the strain changes linearly along the section height, conforming to the assumption of plain section. After equivalent section stress distribution, the calculation formula of the bending capacity of the precast UHPC-RAC composite beams is deduced, and the calculated results are in good agreement with the experimental values.
Preparation technology and mechanism of cementitious material based on solid waste phosphogypsum
ZHENG Yulong, JI Shuai, LU Chunhua, SUN Yutao, ZHAO Hang
2024, 41(3): 1436-1446. doi: 10.13801/j.cnki.fhclxb.20230731.001
Abstract:
A large amount of industrial solid waste phosphogypsum has caused serious pollution to the environment. At the same time, the contradiction between the traditional cement industry with high energy consumption and the realization of the "double carbon" target has become increasingly prominent. Some studies have shown that the cementitious material based on phosphogypsum can replace part of ordinary Portland cement, but its working and mechanical properties are poor when using raw materials without treatment. In this paper, the green and high strength phosphogypsum based cementitious materials were prepared by using common industrial solid wastes such as original phosphogypsum, slag, steel slag and limestone. The results show that chelates are formed by mixing 0.5wt% plant protein with Ca2+ in the gelling system to produce a coordination compound covering the surface of gypsum nucleus, which not only delays the setting time of the gelling material, promotes the hydration reaction degree, but also improves its mechanical properties. The microstructure and composition analysis show that phosphogypsum is mainly used as a filler in the cementitious material, the slag is activated by the alkali of steel slag, and the limestone promotes the hydration reaction while providing Ca2+. Based on the original solid waste phosphogypsum, using the mixture ratio of mphosphogypsummslagmsteel slagmlimestone = 0.45∶0.35∶0.1∶0.1, 28 days flexural strength of mortar specimen is 7.0 MPa, compressive strength is 39.1 MPa, and softening coefficient is 0.91, which is very close to the performance of P·O 42.5 grade ordinary Portland cement.
Dynamic characteristics of polyurethane reinforced sea sand under traffic loads
SHEN Yang, YANG Long, DUAN Liqun, LIU Ruonan, MA Linjian
2024, 41(3): 1447-1457. doi: 10.13801/j.cnki.fhclxb.20230628.001
Abstract:
In order to improve the bearing capacity of sea sand foundation in China, a treatment method for curing of sea sand foundation using polyurethane has been studied. The cyclic traffic load tests on the pure sand and reinforced sand were carried out by using hollow cylinder apparatus under different dynamic stress ratios and loading frequencies. A hollow cylindrical sample preparation method which is suitable for polyurethane rapid and efficient curing sea sand was innovatively designed for the study. And the micro-reinforcement mechanism was analyzed based on SEM results. The experimental results show that: The strain curve and pore pressure development of pure sand are divided into three development trends with the change of dynamic stress ratios, the critical dynamic stress ratio η' obtained by the test is 0.33. The smaller the frequency f under different frequency conditions is, the more obvious the cumulative effect of cyclic load is, the more obvious the development of strain and pore pressure are, bounded by the condition f=1.5 Hz, showing two development trends. The axial cumulative strain of the cured sea sand under the two sets of loading conditions did not exceed 0.7%, and the pore pressure development limit did not exceed 20 kPa. In some conditions, pore pressure eventually turned to be negative, resulting in shear dilatation. The analysis of SEM results shows that the curing agent takes up part of the pores in the sand after reaction. And as a consequence, the curing agent and sea sand forms a stable spatial structure, which leads to an increase of the resistance of particle rearrangement, thereby greatly improving the mechanical properties of the cured sample.
Biological and Nano-composite
Preparation and properties of double crosslinked waste corrugated paper-based aerogel buffer materials
REN Ziming, LI Liangli, JIANG Xiangxiang, YUE Shiqi, LI Hongda, GOU Jinsheng
2024, 41(3): 1458-1469. doi: 10.13801/j.cnki.fhclxb.20230802.002
Abstract:
Waste corrugated paper (WCP) was used as raw material, gelatin (G) and phytic acid (PA) were used as modifiers, and high energy absorption aerogel was prepared by sol-gel method. The effects of G dosage, PA dosage, and reaction temperature on the mechanical properties of dual-crosslinked modified waste paper-based aerogels were investigated. The structural and performance changes of aerogels before and after single modification with G and dual modification with G and PA were characterized by SEM, FTIR, XRD and TGA. The results show that the modified monomer is successfully crosslinked onto the waste paper fiber, and the double crosslinked waste paper based aerogel presents a three-dimensional network structure. Compared with the unmodified and single modified waste paper based aerogel, it has higher thermal stability, excellent thermal insulation (0.045 W·m−1·K−1) and super energy absorption (Absorption energy per unit volume is 253.45 kJ/m3 at 70% strain). The energy absorption capacity is 11.26 and 2.7 times higher than that of expanded polyethylene (EPE) and ethylene vinyl acetate (EVA), respectively. As a green cushioning material in the packaging and transportation process, it has broad application prospects.
Preparation and properties of tannic acid coated abamectin/mesoporous silica nano-pesticide delivery system
XU Peng, DAI Wei, CAO Rong, SHI Weishan, XING Gang, WANG Zhaogui, WANG Shasha, LI Qun, YOU Zhaoqun, HAO Dejun
2024, 41(3): 1470-1479. doi: 10.13801/j.cnki.fhclxb.20230828.002
Abstract:
It is important to increase the retention time of pesticides on the leaf surface of target crops for improving pesticide utilization and reducing the impact of pesticides on the environment. In this paper, we used abamectin (Aba) as a model pesticide and mesoporous silica nanoparticles coated with tannic acid (TA) as a carrier material to construct a nano-pesticide delivery system. Based on the structural and morphological characterization of the nano-pesticide delivery system, we investigated the release performance and foliar adhesion of the nano-pesticide delivery system through simulated release experiments, comparison of contact angle and retention amount on plant foliage and UV photolysis resistance experiments. It is found that tannic acid-coated abamectin-loaded mesoporous silica nanospheres (Aba/MSNs@TA) significantly improve drug wettability on the foliage of Epipremnum aureum, corn and masson pine, and foliar retention is also improved compared to Aba/MSNs. Aba/MSNs@TA exhibits significant pH-responsive release performance, with lower pH environments accelerating the release rate of Aba. In addition, the coating of tannic acid further improves the UV photolytic resistance of the drug in the drug-loaded system.
Metal and Ceramic Matrix Composite
Organization and properties of the surface bionic gradient hardness high strength layer of 17-4PH stainless steel
YAO Jiantao, GAO Cheng, LI Junqiang, LIU Xiaogang
2024, 41(3): 1480-1486. doi: 10.13801/j.cnki.fhclxb.20230731.002
Abstract:
In this paper, it is proposed to prepare a high hardness wear-resistant layer on the surface of 17-4PH stainless steel, and in order to alleviate the problem of cracking between the high hardness cladding layer and the substrate, it is proposed to prepare a bionic gradient hardness surface cladding structure. The use of manual electric arc welding in the 17-4PH stainless steel surface preparation of bionic gradient hardness high strength layer, the choice of D322 electrode and D707 electrode were used as a transition layer and high strength layer in the 17-4PH stainless steel surface for the preparation of the bionic gradient hardness high strength layer, the use of optical microscopy, Vickers hardness tester, X-ray diffractometer, impact testing machine on the high strength layer of the microstructure, microhardness and other properties were characterization. The results show that the bionic gradient hardness high-strength layer prepared on the surface of 17-4PH stainless steel has a uniform organization and good interfacial metallurgical bonding. The organization of the bionic gradient hardness high-strength layer mainly consists of martensite, austenite, WC and carbide. The bionic gradient hardness high-strength layer phase structure mainly consists of Fe-Cr, WC, γ-Fe, with an average hardness of HV0.5 726.5, which is a significant improvement compared with that of the substrate. The bionic gradient hardness high-strength layer on the surface of 17-4PH stainless steel is also a good example of a bionic gradient hardness layer. 17-4PH stainless steel surface bionic gradient hardness high-strength layer average impact absorption power is 12.90 J, the main reason for the reduction of its impact absorption power is due to the different properties between the layers.
Composite Micro-mechanics
Cyclic stress-strain relationship of CFRP-confined recycled aggregates concrete under different loading rates
LI Pengda, XIAN Xujun, REN Yuhao, ZHOU Yingwu
2024, 41(3): 1487-1504. doi: 10.13801/j.cnki.fhclxb.20230831.004
Abstract:
This study experimentally investigated the mechanical behavior of carbon fiber reinforced polymer (CFRP) confined recycled aggregate concrete (RAC) under cyclic loading. In total, 72 CFRP-confined circular RAC specimens were tested under monotonic and cyclic axial compression, with a focus on the various loading rates and recycled aggregate (RA) replacement ratios. Test results indicate that the reinforcing effect of CFRP confinement on the ultimate condition of the concrete with 100wt%RA replacement ratio is most pronounced. However, this enhancement diminishes as the loading rate increases. In comparison to a loading rate of 3 mm/min, for two layers of CFRP-confined concrete with 100wt%RA replacement ratio, the enhancement ratio in ultimate strength is reduced by 16.2%, and the enhancement ratio in ultimate strain is reduced by 22.6% at a loading rate of 18 mm/min. Furthermore, under cyclic axial compression loading, both the unloading stiffness and reloading stiffness exhibit a negative correlation with the RA replacement ratio and loading rate. Nevertheless, the loading rate increase weakens the RA ratio's influence. Based on a regression analysis of the experimental data, a new cyclic stress-strain model for CFRP-confined recycled aggregate concrete incorporating the coupled effects of loading rate and RA replacement ratio is proposed. The proposed model exhibits excellent agreement with the experimental curves in this paper and the collected stress-strain curves from the opening literature.
Study on fracture of fiber-reinforced composite single layer laminate based on adaptive double phase-field model
GUO Wen, MA Yu'e, SUNDAR Natarajan, CHEN Pengcheng, PENG Fan
2024, 41(3): 1505-1515. doi: 10.13801/j.cnki.fhclxb.20230816.003
Abstract:
The phase-field method can automatically capture crack initiation and propagation, which has obvious advantages in simulating complex fracture behaviors in composites. To distinguish different fracture modes in fiber-reinforced composites (FRC), two phase-field variables were introduced to represent the damage evolution of fiber and matrix, respectively. An adaptive mesh refinement scheme based on the quadtree decomposition was incorporated into the anisotropic double phase-field formulations using the phase-field variables as the error indicators. The corresponding Matlab programs were designed and developed to study the fracture behaviors of the unidirectional and variable stiffness fiber-reinforced composite single layer laminate under tensile load. The results show that: The numerical results are in good agreement with the experimental results; and the adaptive double phase-field method can not only guarantee high computational accuracy but also refine the mesh along the crack paths with the evolution of phase-field parameters automatically and accurately. Moreover, this method can simplify the mesh pre-processing process, greatly reduce the number of unnecessary elements and the calculation cost, improve the calculation efficiency.
Fatigue performance analysis of composite joints based on hole deformation
LIU Xueshu, WANG Xueyao
2024, 41(3): 1516-1527. doi: 10.13801/j.cnki.fhclxb.20230619.001
Abstract:
In the practical application of composite materials, using the failure of assembly components or faste-ners as a criterion for determining the failure of composite bolted joints brings great risks. After analysis of development characteristics of fatigue damage in composite materials, a method for predicting the fatigue life of composite bolted joints was proposed, which was based on the deformation of connection holes, and validated by using experimental data on tensile-tensile fatigue performance of double-bolt single-lap and single-bolt double-lap composite joints. The results show that the deformation of the connection hole can well reflect the development process of fatigue damage of the connection structure, and the maximum relative error of the fatigue life prediction model proposed in this paper does not exceed −3.62%. The existence of assembly gaps can lead to a decrease in the fatigue life of the connection member of up to 64.8%.
Quasi-fiber scale modelling of 3D woven preforms
ZHU Wanqing, XIE Junbo, WU Lanfang, CHEN Li, YANG Lin, LIU Jingyan
2024, 41(3): 1528-1538. doi: 10.13801/j.cnki.fhclxb.20230816.002
Abstract:
3D woven composites are widely used in the aerospace field. As a reinforcement structure, the geometry of fiber preform has a decisive influence on the mechanical properties of composites. However, a preform is a flexible structure that is prone to significant geometric variation during the molding process, including yarn path changes and compressive deformations of cross-sections. Achieving refined and high-fidelity modeling of preforms is an important prerequisite for performance prediction and structural design of composite materials. Aiming at modeling of the complex fiber structure for carbon fiber 3D woven preforms, a quasi-fiber scale modeling method based on the concept of virtual fiber was proposed. Movements and deformations of yarn in the weaving process were simulated, and high precision model of 3D woven preform was constructed. The Micro-CT technology was used to analyze the unit cell structure inside the preform sample, which verified the reliability of the model.
Damage identification method for fiber-reinforced composite laminates based on element-level damage indicators
SHI Qinghe, YANG Ying, SUN Wei, WANG Hao, HU Kejun
2024, 41(3): 1539-1553. doi: 10.13801/j.cnki.fhclxb.20230710.002
Abstract:
An element-level damage index, damage index of laminated element, was proposed for composite laminate structures that can comprehensively reflect the degradation of load-bearing capacity, which can reflect the damage of stiffness in both internal and external directions and has the advantages of fewer parameters and easier identification. In order to ensure the rationality of the proposed damage index, mathematical and mechanical operators was used to equate the element-level damage index with the material-level damage index, and the differences between different damage indexes in characterizing the degree of damage were compared. The damage identification process of composite structures based on element-level damage parameters was also proposed, i.e., the damage elements were firstly screened by using modal strain energy change ratio, and then the damage degree of the candidate elements was identified by using optimization methods. The proposed method was validated by numerical examples and an experiment work, and the correlation between the elements of the element-level damage parameters was analyzed and the damage identification process of the composite laminate structure based on the element-level damage parameters was validated. The results of this paper complement the existing theory of health monitoring of composite structures.
Effect of porosity defects on crack initiation and propagation behavior in SiC/AZ91D composites
LI Buwei, YAO Junping, CHEN Guoxin, LI Yiran, LIANG Chaoqun
2024, 41(3): 1554-1566. doi: 10.13801/j.cnki.fhclxb.20230711.002
Abstract:
Using the finite element analysis method, this study introduced porosity defects into SiC/AZ91D magnesium matrix composites with realistic SiC particle morphology, and analyzed the influence of different porosity rates and shapes on the mechanical behavior of SiC/AZ91D composites during uniaxial tensile process. The results show that when the aspect ratio of the pore length to width is 1, the tensile strengths of the composites with void contents of 0%, 0.5%, 1.0%, and 1.5% are 351.214 MPa, 339.452 MPa, 325.735 MPa and 306.791 MPa, respectively. The tensile strength gradually decreases with the increase of porosity rate, and the initiation and propagation time of cracks in the composite material advances with the increase of porosity rate. As the aspect ratio of the pore length to width increases, the stress concentration at the tip of the pore becomes more severe, resulting in lower tensile strength of the composite material. The crack initiation and propagation mechanism in the SiC/AZ91D composite material without porosity defects involves the initiation of microcracks at the particle-matrix interface, followed by their interconnection to form a main crack, which propagates around the particles leading to material fracture. In the case of SiC/AZ91D composites with porosity, microcracks initiate around the pores and interconnect with microcracks generates at the particle-matrix interface, ultimately converging into a main crack that propagates around the particles, causing material fracture.
Mode II interlaminar mechanical behavior of needled/stitched multiscale interlocking composites
SU Xingzhao, CHEN Xiaoming, ZHENG Hongwei, WU Kaijie, XIN Shiji, GUO Dongsheng
2024, 41(3): 1567-1576. doi: 10.13801/j.cnki.fhclxb.20230711.001
Abstract:
Needled/stitched multi-scale interlocking composites have excellent interlaminar properties and are increasingly used in aerospace thermal structure composites. However, the effect of stitch technology on double incision interlaminar shear (DNS) performance of needle composites remains unclear. Using quartz satin fabric and quartz twill half-cut fabric as materials, quartz fiber-reinforced resin-based needle/stitch multi-scale interlocking composites with three kinds of stitch pattern and four kinds of stitch fiber bundles were designed and prepared. The DNS performance of the composite was tested and analyzed. The internal structure of the fabric was characterized by micro-CT, and the fracture morphology of the sample was observed by scanning electron microscopy (SEM) to clarify the mechanism of interlayer strengthening. The DNS behavior of needled/stitched multi-scale interlocking composites was further investigated by cohesive zone model (CZM) and Abaqus software, and the ultimate failure strength was predicted. The results show that the introduction of stitch technology greatly improves the interlamellar properties of the composite, and the maximum failure load of DNS reaches 32.73 MPa, which is 86.46% higher than that of the needled composite. The main failure modes of multi-scale interlocking composite DNS are matrix cracking, brittle fracture and pulling out of fiber bundle. At the same time, the simulation results are in good agreement with the DNS experimental results of needled/stitched multi-scale interlocking composites, and the maximum error is less than 8%, which proves that the cohesion model established in this paper can effectively predict the interlaminar shear performance of needled/stitched multi-scale interlocking composites.
Numerical simulation of hot forming of aluminum-carbon fiber reinforced polypropylene hybrid hat-shaped rail
WANG Zhen, CAO Xi'ao, MEI Xuan, ZHU Guohua, CHEN Yisong, GUO Yingshi
2024, 41(3): 1577-1587. doi: 10.13801/j.cnki.fhclxb.20230714.003
Abstract:
Aluminum alloy (Al)-carbon fiber reinforced polypropylene (CF/PP) hybrid materials can be quickly formed into thin-walled components of the vehicle body by the hot press molding technology, and has broad application prospects in the lightweight design of automobiles. However, the Al mainly exhibits plastic deformation while the CF/PP mainly exhibits fabric tensile/shear deformations during the hot pressing process; In addition, the Al-CF/PP hybrid materials exhibit significant thermo-mechanical coupling characteristics, which bring huge challenges to numerical model developments and hot forming characteristic studies. The 8-layer (Al and CF/PP are alternately and symmetrically laid) Al-CF/PP hybrid hat-shaped rail specimen was prepared by the hot pressing technology, and the fiber angle variations were characterized through the X-ray computed tomography (X-ray CT) layer-by-layer, and the results indicate that the fabrics in Al-CF/PP undergo significant shear deformations; Then, the uniaxial and biaxial tensile experiments were conducted for Al sheets and CF/PP sheets under different temperature conditions, and the temperature-dependent material constitutive model of Al-CF/PP was constructed; And the hot press molding finite element model of the Al-CF/PP hat-shaped rail was developed in ABAQUS, and the predicted fiber angle variations by the simulation are basically consistent with the experimental results. The results indicate that all Al sheets occur thickness reductions, all CF/PP sheets undergo obvious shear deformations and interlayer materials between Al and CF/PP occur significant failure damages during the hot press molding process.
Energy consumption and constitutive relationship of interface between corrugated steel plate and concrete
WANG Wei, LI Pengluo, LIN Zhongliang, MI Jiaxin, WANG Xiaofei, XU Jian, JIA Yu
2024, 41(3): 1588-1600. doi: 10.13801/j.cnki.fhclxb.20230919.001
Abstract:
To study the interface bonding and sliding performance of corrugated steel plate concrete, considering the thickness of concrete cover, concrete strength, embedded length and stirrup ratio, the push out tests of 12 corrugated steel plate concrete specimens were completed, the failure modes of the specimens were analyzed and summarized, the composition of interfacial bonding force at different stages was analyzed based on the interfacial bonding slip mechanism, and the bonding performance of corrugated steel plate concrete was studied from the perspective of interface energy consumption. The results show that the concrete cracks at the trough develop from the outside to the inside. Under the action of interfacial compressive stress and stirrup tension, the crack of concrete at wave ridge is 45° with the extension line of wave ridge. The ultimate bond strength of the interface is between 0.99 and 1.86 MPa, and the residual bond strength is between 0.25 and 0.63 MPa. Increasing the embedded length can improve the elastic deformation energy of the interface and the ultimate bond strength of the interface. Finally, considering the four influencing factors, the bond stress-slip constitutive relation expression of the interface between corrugated steel plate concrete was proposed and verified by finite element analysis. It is found that the simulated curve is in good agreement with the experimental curve, which shows that the proposed constitutive relation expression is reasonable and accurate, and can provide a reference for the finite element analysis of corrugated steel plate concrete structure.
Vibration response analysis of fiber reinforced composite thin-walled truncated conical shell based on multilevel iterative correction
XU Zhuo, XU Peiyao, CHU Chen, YAO Nan, LI Hui, GU Dawei, LI He, WEN Bangchun
2024, 41(3): 1601-1610. doi: 10.13801/j.cnki.fhclxb.20230625.001
Abstract:
A vibration response analysis model was established for a fiber-reinforced composite thin-walled truncated conical shell. Based on the structural characteristics of the fiber-reinforced composite thin-walled truncated conical shell, the theoretical modeling of the structure was carried out using plate shell vibration theory and complex elastic modulus methods, considering the angle between the basic excitation load direction and the generatrix, the angle between the fiber laying direction and the x-axis. The vibration mode function was expressed using the bi-directional beam function method, and the natural characteristics and vibration response were solved using the energy method and modal superposition method. In order to verify the correctness of the model, vibration characteristic tests were conducted on a TC300/epoxy resin-based fiber-reinforced composite thin-walled truncated cone shell using a self-built vibration test platform. To reduce the influence of material parameter errors caused by sample processing, a dichotomous particle swarm algorithm iteration method was developed to correct the material parameters. The results show that the maximum error between the test results and the theoretically calculated resonance response is within 3.0%, which verifies the correctness and effectiveness of the proposed theoretical model and calculation method.
Low-velocity impact properties of foam sandwich composites with different thicknesses prepared via thermal expansion molding process
MIN Wei, CHENG Lele, YU Muhuo, SUN Zeyu
2024, 41(3): 1611-1625. doi: 10.13801/j.cnki.fhclxb.20230710.003
Abstract:
Thermal expansion molding process is expected to be integrated to form various foam sandwich composites. The expandable epoxy foam prepreg with an initial thickness of 1 mm was selected, and four kinds of foam sandwich panels with different thicknesses were prepared by controlling the mold cavity size and different molding pressures. The impact energies of 10 J and 42 J were used to study the effects of thermal expansion process and core thickness on the low-velocity impact properties of foam sandwich composites. The damage patterns of different specimens were investigated by ABAQUS finite element analysis, ultrasonic C-scan and the test data. Compression after impact tests were conducted to investigate the damage tolerance of different specimens. The results show that the foam core with higher expansion rate produces lower expansion force, and the impact strength of the foam sandwich board is reduced, but the structure has better energy absorption effect. Both high impact energy and low strength foam cores lead to higher damage degree of the skin. The compression strength decay rate of the sample at 10 J impact energy is 8.2%, and the compression strength decay rate of the sample at 42 J impact energy is 38.2%. The forming pressure and the thickness of the core have little effect on the damage tolerance of the foam sandwich plate. The high designability of structural and impact resistance properties of foam sandwich composites formed by thermal expansion process was determined.
Dynamic characteristics and mechanisms of table tennis blades with the inclusion of special fiber laminates
YIN Tiantian, HAO Liling, ZHAO Xinliang, FU Zhiqiang, LIU Chidong, HE Shan
2024, 41(3): 1626-1632. doi: 10.13801/j.cnki.fhclxb.20230703.002
Abstract:
Several series of special fiber laminates with different performance were designed and fabricated by chemical vapor deposition method. The dynamic responses of table tennis blades were found adjustable with the inclusion of different fiber laminates. The dynamic characteristics and mechanisms of the blades were analyzed and measured by finite element method (FEM) and non-contact mode measurement method. The first and second order frequencies of the blades can be adjusted in the range of 115-127 Hz, and 179-198 Hz, respectively, which cover the performances of most popular market products. The FEM and non-contact mode measurement method are both proved to be feasible on designing and studying the characteristics of table tennis blades.