2023 Vol. 40, No. 11
2023, 40(11): 5977-5988.
doi: 10.13801/j.cnki.fhclxb.20230515.002
Abstract:
Metal-organic frameworks (MOFs) are widely used in materials because of their large specific surface area, adjustable porosity and pore size, strong surface modification function, and good chemical and thermal stability. However, MOFs are prone to agglomeration, and their inherent crystal structure leads to poor flexibility, processability and recyclability, which severely limits their application. In recent years, MOFs have been compounded with environmentally friendly and renewable biomass materials, which not only solves the above problems, but also combines the advantages of biomass and MOFs to realize their application in emerging fields. Starting from different biomass raw materials, this paper introduces the types and preparation methods of MOFs/biomass matrix composites, reviews the research progress of MOFs/biomass matrix composites in water purification, gas separation, antibacterial treatment and electrochemical application in detail, and puts forward constructive suggestions for the problems existing in the preparation and application process, in order to provide a scientific basis for researchers to design and develop high-performance MOFs/biomass composites.
Metal-organic frameworks (MOFs) are widely used in materials because of their large specific surface area, adjustable porosity and pore size, strong surface modification function, and good chemical and thermal stability. However, MOFs are prone to agglomeration, and their inherent crystal structure leads to poor flexibility, processability and recyclability, which severely limits their application. In recent years, MOFs have been compounded with environmentally friendly and renewable biomass materials, which not only solves the above problems, but also combines the advantages of biomass and MOFs to realize their application in emerging fields. Starting from different biomass raw materials, this paper introduces the types and preparation methods of MOFs/biomass matrix composites, reviews the research progress of MOFs/biomass matrix composites in water purification, gas separation, antibacterial treatment and electrochemical application in detail, and puts forward constructive suggestions for the problems existing in the preparation and application process, in order to provide a scientific basis for researchers to design and develop high-performance MOFs/biomass composites.
2023, 40(11): 5989-6009.
doi: 10.13801/j.cnki.fhclxb.20230523.002
Abstract:
Ti/Mg bimetallic composite possesses the virtues of both elements and is endowed with significant potential for multiple applications in fields such as aerospace, transportation, and others. Recently, it has been widely concerned by global scholars and researchers. Employing an interlayer metal as a typical means of interfacial strengthening to realize the metallurgical bonding of Ti and Mg alloys for a substantial discrepancy in melting points, weak metallurgical reaction, and low mutual solid solubility between Mg and Ti. The control and optimization of interfacial reaction are crucial in enhancing interfacial bonding strength, but also the difficulty of interfacial strengthening. Overview of research progress of Ti/Mg bimetallic composites fabricated by different join methods and analyzing the effect of interfacial microstructure on interfacial bonding strength was analyzed. The interfacial bonding strength with different interfacial strengthening methods under various join technology was listed. The Ti/Mg bimetallic interface bonding mechanism was summarized and the future research of Ti/Mg bimetallic interfacial strengthening has been prospected.
Ti/Mg bimetallic composite possesses the virtues of both elements and is endowed with significant potential for multiple applications in fields such as aerospace, transportation, and others. Recently, it has been widely concerned by global scholars and researchers. Employing an interlayer metal as a typical means of interfacial strengthening to realize the metallurgical bonding of Ti and Mg alloys for a substantial discrepancy in melting points, weak metallurgical reaction, and low mutual solid solubility between Mg and Ti. The control and optimization of interfacial reaction are crucial in enhancing interfacial bonding strength, but also the difficulty of interfacial strengthening. Overview of research progress of Ti/Mg bimetallic composites fabricated by different join methods and analyzing the effect of interfacial microstructure on interfacial bonding strength was analyzed. The interfacial bonding strength with different interfacial strengthening methods under various join technology was listed. The Ti/Mg bimetallic interface bonding mechanism was summarized and the future research of Ti/Mg bimetallic interfacial strengthening has been prospected.
2023, 40(11): 6010-6028.
doi: 10.13801/j.cnki.fhclxb.20230601.001
Abstract:
In the context of energy crisis and continuous deterioration of ecological environment, the development of advanced energy storage technology has become the focus of competing research in global. Structural supercapacitor composites (SSC) with both energy storage and structural bearing capacity are developed by using multifunctional carbon fiber electrode and polymer electrolyte, which is expected to meet the dual demands of modern equipment for efficient energy storage and lightweight structures. Therefore, SSC has a wide application prospect in electric vehicles, aerospace and other fields. Carbon fiber electrode is a key component of SSC, which plays an important role in charge accumulation and mechanical loading. It should have high specific surface area, excellent mechanical properties and good wettability with polymer electrolyte. However, the pristine surface of carbon fiber is smooth and chemically inert, which is not conducive to ion storage and resin electrolyte infiltration in carbon fiber electrodes, and thus limits the preparation and application of high-performance SSC, so surface modification of carbon fiber electrode is necessary. This paper introduces the current research status of carbon fiber electrode materials for SSC, mainly focuses on several important surface modification methods of carbon fiber (such as chemical etching activation, modification with carbon-based active materials, modification with nano metal compounds and polyaniline modification), summarizes the influence of different carbon fiber electrode preparation methods on the energy storage and mechanical properties of SSC and the corresponding mechanisms, and their respective advantages and disadvantages. The challenges and development trend of carbon fiber electrode for SSC are also prospected.
In the context of energy crisis and continuous deterioration of ecological environment, the development of advanced energy storage technology has become the focus of competing research in global. Structural supercapacitor composites (SSC) with both energy storage and structural bearing capacity are developed by using multifunctional carbon fiber electrode and polymer electrolyte, which is expected to meet the dual demands of modern equipment for efficient energy storage and lightweight structures. Therefore, SSC has a wide application prospect in electric vehicles, aerospace and other fields. Carbon fiber electrode is a key component of SSC, which plays an important role in charge accumulation and mechanical loading. It should have high specific surface area, excellent mechanical properties and good wettability with polymer electrolyte. However, the pristine surface of carbon fiber is smooth and chemically inert, which is not conducive to ion storage and resin electrolyte infiltration in carbon fiber electrodes, and thus limits the preparation and application of high-performance SSC, so surface modification of carbon fiber electrode is necessary. This paper introduces the current research status of carbon fiber electrode materials for SSC, mainly focuses on several important surface modification methods of carbon fiber (such as chemical etching activation, modification with carbon-based active materials, modification with nano metal compounds and polyaniline modification), summarizes the influence of different carbon fiber electrode preparation methods on the energy storage and mechanical properties of SSC and the corresponding mechanisms, and their respective advantages and disadvantages. The challenges and development trend of carbon fiber electrode for SSC are also prospected.
2023, 40(11): 6029-6042.
doi: 10.13801/j.cnki.fhclxb.20230515.001
Abstract:
Cation doping measures are considered as one of the effective measures to optimize the performance of Cu2ZnSn(S,Se)4 (CZTS(Se)) thin film solar cells, and divalent cation doping measures are the most studied and widely applied in all cation doping measures. Here, the research progress of divalent cation measures in optimizing the performance of CZTS(Se) thin film solar cells is introduced from two aspects: Cations substitution and extra cations addition. Divalent cations substitution measures, such as, substitution of Zn2+ with Cd2+, mainly reduce the defect density of the absorber layer of CZTS(Se) thin film solar cells, improve the crystalline quality, and solve the problem of large interface energy band offset between the absorber layer and buffer layer, thus reducing the open voltage circuit loss of the device and improving its efficiency. The extra addition of divalent cations, such as, the extra addition of Co2+/Mn2+, can optimize the crystallinity of the film, help the carrier transport, and improve the electrical properties of the absorber layer. Finally, their advantages, disadvantages, and the application prospects are also summarized.
Cation doping measures are considered as one of the effective measures to optimize the performance of Cu2ZnSn(S,Se)4 (CZTS(Se)) thin film solar cells, and divalent cation doping measures are the most studied and widely applied in all cation doping measures. Here, the research progress of divalent cation measures in optimizing the performance of CZTS(Se) thin film solar cells is introduced from two aspects: Cations substitution and extra cations addition. Divalent cations substitution measures, such as, substitution of Zn2+ with Cd2+, mainly reduce the defect density of the absorber layer of CZTS(Se) thin film solar cells, improve the crystalline quality, and solve the problem of large interface energy band offset between the absorber layer and buffer layer, thus reducing the open voltage circuit loss of the device and improving its efficiency. The extra addition of divalent cations, such as, the extra addition of Co2+/Mn2+, can optimize the crystallinity of the film, help the carrier transport, and improve the electrical properties of the absorber layer. Finally, their advantages, disadvantages, and the application prospects are also summarized.
2023, 40(11): 6043-6060.
doi: 10.13801/j.cnki.fhclxb.20230612.001
Abstract:
With the continuous development of electronic equipment towards miniaturization, integration and multifunction, the high thermal conductivity of electronic materials has become critically significant to ensure the stable operation and service life of electronic equipment. Polyimide (PI) is widely used in the thermal management field because of its excellent heat resistance and mechanical properties. However, the intrinsic thermal conductivity of traditional PI is low, which is difficult to meet the rapid heat dissipation requirements of electronic devices. The development of new highly thermally conductive PI and PI composites has become a research hotspot. This paper introduces the preparation and performance regulation of amorphous polyimides and liquid crystalline polyimides based on the molecular chain structure, molecular chain orientation and molecular interaction of intrinsic thermally conductive PI, and discusses the influence of surface modification, constructing hybrid fillers, orientation design, three-dimensional network structure on the structure and performance of PI composites. Finally, the challenges of highly thermally conductive PI and PI composites are summarized and prospected.
With the continuous development of electronic equipment towards miniaturization, integration and multifunction, the high thermal conductivity of electronic materials has become critically significant to ensure the stable operation and service life of electronic equipment. Polyimide (PI) is widely used in the thermal management field because of its excellent heat resistance and mechanical properties. However, the intrinsic thermal conductivity of traditional PI is low, which is difficult to meet the rapid heat dissipation requirements of electronic devices. The development of new highly thermally conductive PI and PI composites has become a research hotspot. This paper introduces the preparation and performance regulation of amorphous polyimides and liquid crystalline polyimides based on the molecular chain structure, molecular chain orientation and molecular interaction of intrinsic thermally conductive PI, and discusses the influence of surface modification, constructing hybrid fillers, orientation design, three-dimensional network structure on the structure and performance of PI composites. Finally, the challenges of highly thermally conductive PI and PI composites are summarized and prospected.
2023, 40(11): 6061-6072.
doi: 10.13801/j.cnki.fhclxb.20230626.001
Abstract:
The interfacial interactions between carbon fiber (CF) and polyetherketoneketone (PEKK) are poor due to the chemical inertness of CF, limiting the mechanical properties of carbon fiber reinforced polyetherketoneketone (CF/PEKK) composites. In this study, a water-based sizing agent of sulfonated polyetherketoneketone (SPEKK) was prepared by sulfonating domestic PEKK resin, in order to improve the mechanical properties of CF/PEKK composites. By regulating the sulfonation degree, the stable SPEKK aqueous emulsion was obtained and used for CF sizing modification. Subsequently, CF/PEKK composites were fabricated via vacuum hot-press technique. When the concentration of SPEKK aqueous emulsion was 0.5wt%, the flexural strength, flexural modulus and interlaminar shear strength of the modified CF/PEKK composites reached 1237 MPa, 78 GPa, and 92 MPa, which were 35.5%, 5.4%, and 26.0% higher than that of the unmodified CF/PEKK composites, respectively. Such enhancement in mechanical properties could be attributed to the introduced SPEKK on the CF surfaces, which could form hydrogen bonds and π-π interactions with CF, as well as π-π interactions and diffusion and entanglement with PEKK, significantly promoting the interfacial bonding between CF and PEKK. As a simpler process, CF surface modification with water-based SPEKK sizing agent is environmentally friendly and suitable for the industrial production, which is of great significance for the development of domestic high-performance carbon fiber reinforced thermoplastic composites.
The interfacial interactions between carbon fiber (CF) and polyetherketoneketone (PEKK) are poor due to the chemical inertness of CF, limiting the mechanical properties of carbon fiber reinforced polyetherketoneketone (CF/PEKK) composites. In this study, a water-based sizing agent of sulfonated polyetherketoneketone (SPEKK) was prepared by sulfonating domestic PEKK resin, in order to improve the mechanical properties of CF/PEKK composites. By regulating the sulfonation degree, the stable SPEKK aqueous emulsion was obtained and used for CF sizing modification. Subsequently, CF/PEKK composites were fabricated via vacuum hot-press technique. When the concentration of SPEKK aqueous emulsion was 0.5wt%, the flexural strength, flexural modulus and interlaminar shear strength of the modified CF/PEKK composites reached 1237 MPa, 78 GPa, and 92 MPa, which were 35.5%, 5.4%, and 26.0% higher than that of the unmodified CF/PEKK composites, respectively. Such enhancement in mechanical properties could be attributed to the introduced SPEKK on the CF surfaces, which could form hydrogen bonds and π-π interactions with CF, as well as π-π interactions and diffusion and entanglement with PEKK, significantly promoting the interfacial bonding between CF and PEKK. As a simpler process, CF surface modification with water-based SPEKK sizing agent is environmentally friendly and suitable for the industrial production, which is of great significance for the development of domestic high-performance carbon fiber reinforced thermoplastic composites.
2023, 40(11): 6073-6086.
doi: 10.13801/j.cnki.fhclxb.20230117.005
Abstract:
The interfacial properties between polymer and fiber are particularly important for improving the mechanical properties of composites. In this paper, the surface of nano-SiO2 was modified by polyurethane (PU) capped by isocyanate (—NCO), and the surface of carbon fiber (CF) was modified by KH550. Because of the high reactivity of —NH2 and —NCO, the covalent bond was formed between CF and nano-SiO2 particles through PU molecular chain. The results showed that the introduction of PU polar molecular chain improved the surface energy and wettability of CF. Compared with the CF directly grafted with nano particles by KH550(CF-KH550-SiO2), the surface energy of the CF with nano particles linked by PU (CF-KH550-PU-SiO2) molecules increased by 23.0%, and the grafting rate and dispersion uniformity of surface nano SiO2 particles also improved significantly. Compared with the untreaed CF/epoxy resin (EP) composites, the interfacial strength (IFSS) and the interlaminar shear strength (ILSS) of CF-KH550-PU-SiO2/EP composites increased by 72.9% and 47.9% respectively. Compared with the CF-KH550-SiO2/EP composites, IFSS and ILSS of CF-KH550-PU-SiO2/EP composites increased by 17.3% and 11.2%, respectively.
The interfacial properties between polymer and fiber are particularly important for improving the mechanical properties of composites. In this paper, the surface of nano-SiO2 was modified by polyurethane (PU) capped by isocyanate (—NCO), and the surface of carbon fiber (CF) was modified by KH550. Because of the high reactivity of —NH2 and —NCO, the covalent bond was formed between CF and nano-SiO2 particles through PU molecular chain. The results showed that the introduction of PU polar molecular chain improved the surface energy and wettability of CF. Compared with the CF directly grafted with nano particles by KH550(CF-KH550-SiO2), the surface energy of the CF with nano particles linked by PU (CF-KH550-PU-SiO2) molecules increased by 23.0%, and the grafting rate and dispersion uniformity of surface nano SiO2 particles also improved significantly. Compared with the untreaed CF/epoxy resin (EP) composites, the interfacial strength (IFSS) and the interlaminar shear strength (ILSS) of CF-KH550-PU-SiO2/EP composites increased by 72.9% and 47.9% respectively. Compared with the CF-KH550-SiO2/EP composites, IFSS and ILSS of CF-KH550-PU-SiO2/EP composites increased by 17.3% and 11.2%, respectively.
2023, 40(11): 6087-6097.
doi: 10.13801/j.cnki.fhclxb.20230407.001
Abstract:
Ultra-high molecular weight polyethylene (UHMWPE) fiber reinforced composites are considered as state-of-the-art materials for armor solutions, and interlaminar delamination is one of the main failure mechanisms for the composites under impact loadings. For UHMWPE composite laminates, an improved double cantilever beam (DCB) specimen was proposed. The interlaminar fracture toughness (GIC) and failure characteristics were then studied. Analysis were conducted regarding the influence of the specimen thickness and fiber layups on the GIC. The failure mechanism of interlaminar fracture and the effect of structural plasticity on the crack propagation process were further discussed. Evaluation was also implemented on the applicability of the existing test standards for the calculation of the interlaminar fracture toughness. Results show that the DCB specimen with small thickness exhibits obvious plastic behavior, and the measured interlaminar fracture toughness is significantly affected by structural plasticity. Increasing the thickness of the specimen can effectively avoid the influence of plasticity. Conclusively, the results presented in this paper provide experimental reference and data support for the study of dynamic interlaminar properties and theoretical models of UHMWPE composites, that have important engineering significance for the design of composite protective structures.
Ultra-high molecular weight polyethylene (UHMWPE) fiber reinforced composites are considered as state-of-the-art materials for armor solutions, and interlaminar delamination is one of the main failure mechanisms for the composites under impact loadings. For UHMWPE composite laminates, an improved double cantilever beam (DCB) specimen was proposed. The interlaminar fracture toughness (GIC) and failure characteristics were then studied. Analysis were conducted regarding the influence of the specimen thickness and fiber layups on the GIC. The failure mechanism of interlaminar fracture and the effect of structural plasticity on the crack propagation process were further discussed. Evaluation was also implemented on the applicability of the existing test standards for the calculation of the interlaminar fracture toughness. Results show that the DCB specimen with small thickness exhibits obvious plastic behavior, and the measured interlaminar fracture toughness is significantly affected by structural plasticity. Increasing the thickness of the specimen can effectively avoid the influence of plasticity. Conclusively, the results presented in this paper provide experimental reference and data support for the study of dynamic interlaminar properties and theoretical models of UHMWPE composites, that have important engineering significance for the design of composite protective structures.
2023, 40(11): 6098-6109.
doi: 10.13801/j.cnki.fhclxb.20230109.001
Abstract:
The research on improving the interlayer mechanical properties and heat resistance of epoxy resin matrix composites through toughening modification of epoxy resin matrix has important engineering application value. Modified resin (ES) was prepared by condensation reaction of hydroxyl terminated polydimethylsiloxane and epoxy resin, and glass fiber reinforced modified epoxy resin matrix composite (ES-GF) was prepared by vacuum introduction method. The interlaminar mechanical properties of the composite were measured by double cantilever beam and short beam shear tests. The thermal resistance of the composite was evaluated by thermogravimetry and dynamic mechanical thermal testing. The interlaminar mechanical properties and thermal resistance of the corresponding glass fiber reinforced unmodified epoxy matrix composites (EP-GF) were also tested for compara-tive analysis. In order to analyze the physical mechanism of strengthening the interlaminar mechanical properties and improving the heat resistance of the composite, the tensile strength, tensile modulus, flexural strength, flexural modulus, tensile elongation at break, pendulum impact strength and microstructure characteristics of the epoxy resin before and after modification were also measured and characterized. The experimental results show that, compared with EP-GF, the release rate of type I critical strain energy (fracture toughness) of ES-GF is increased by 98.1%, and the interlaminar shear strength is increased by 13.3%. The strengthening of interlaminar mechanical properties is attributed to the comprehensive effect of Si—O bond flexible chain segment, "ductile points" playing a "nail anchor" role and improvement of fiber/matrix wettability. The maximum thermal weight loss rate of ES is decreased by 33.1%, and the final residue at 800℃ is increased by 13.5 times. Before glass transition temperature Tg, the storage modulus of ES-GF is 1.3 GPa higher than that of EP-GF, and after Tg, the storage modulus of ES-GF is nearly 1.3 GPa higher than that of EP-GF, and the glass transition temperature of siloxane modified epoxy resin is slightly increased.
The research on improving the interlayer mechanical properties and heat resistance of epoxy resin matrix composites through toughening modification of epoxy resin matrix has important engineering application value. Modified resin (ES) was prepared by condensation reaction of hydroxyl terminated polydimethylsiloxane and epoxy resin, and glass fiber reinforced modified epoxy resin matrix composite (ES-GF) was prepared by vacuum introduction method. The interlaminar mechanical properties of the composite were measured by double cantilever beam and short beam shear tests. The thermal resistance of the composite was evaluated by thermogravimetry and dynamic mechanical thermal testing. The interlaminar mechanical properties and thermal resistance of the corresponding glass fiber reinforced unmodified epoxy matrix composites (EP-GF) were also tested for compara-tive analysis. In order to analyze the physical mechanism of strengthening the interlaminar mechanical properties and improving the heat resistance of the composite, the tensile strength, tensile modulus, flexural strength, flexural modulus, tensile elongation at break, pendulum impact strength and microstructure characteristics of the epoxy resin before and after modification were also measured and characterized. The experimental results show that, compared with EP-GF, the release rate of type I critical strain energy (fracture toughness) of ES-GF is increased by 98.1%, and the interlaminar shear strength is increased by 13.3%. The strengthening of interlaminar mechanical properties is attributed to the comprehensive effect of Si—O bond flexible chain segment, "ductile points" playing a "nail anchor" role and improvement of fiber/matrix wettability. The maximum thermal weight loss rate of ES is decreased by 33.1%, and the final residue at 800℃ is increased by 13.5 times. Before glass transition temperature Tg, the storage modulus of ES-GF is 1.3 GPa higher than that of EP-GF, and after Tg, the storage modulus of ES-GF is nearly 1.3 GPa higher than that of EP-GF, and the glass transition temperature of siloxane modified epoxy resin is slightly increased.
2023, 40(11): 6110-6118.
doi: 10.13801/j.cnki.fhclxb.20230105.004
Abstract:
Constructing thermal conductive pathways in polymer matrix with interconnected high conductive thermal fillers is an effective strategy to enhance the thermal conductivity of the composites. In this paper, eutectic Sn-Bi alloy (Sn57Bi43) nanoparticles are deposited on the surface of Al2O3 microspheres by coreduction method to prepare Al2O3-Sn57Bi43 hybrids as thermal conductive and electrical insulating fillers for epoxy resin. During the heat curing of epoxy resin, Sn57Bi43 nanoparticles on the Al2O3 surface melt and bridge the separate fillers together to form effective thermal conductive pathway, and thus enhance the thermal conductivity of the composites. When filler volume fraction is 60vol%, the thermal conductivity of Al2O3-Sn57Bi43/epoxy composites is 2.95 W·(m·K)−1, 62.1% higher than that of Al2O3/epoxy composites (1.82 W·(m·K)−1). The results of Fogyel and Agari simulation demonstrate that the deposition of Sn57Bi43 on Al2O3 surface reduces the thermal contact resistance between fillers and forms thermally conductive networks more easily. The Al2O3-Sn57Bi43/epoxy composites exhibit higher dielectric loss, lower dielectric strength and volume resistivity than Al2O3/epoxy composites, still with electrical insulating properties. What is more, the tensile strength of the Al2O3-Sn57Bi43/epoxy composites is improved, because the improved interfacial properties of filler-matrix and the formed networks could transfer stress and prevent crack expansion.
Constructing thermal conductive pathways in polymer matrix with interconnected high conductive thermal fillers is an effective strategy to enhance the thermal conductivity of the composites. In this paper, eutectic Sn-Bi alloy (Sn57Bi43) nanoparticles are deposited on the surface of Al2O3 microspheres by coreduction method to prepare Al2O3-Sn57Bi43 hybrids as thermal conductive and electrical insulating fillers for epoxy resin. During the heat curing of epoxy resin, Sn57Bi43 nanoparticles on the Al2O3 surface melt and bridge the separate fillers together to form effective thermal conductive pathway, and thus enhance the thermal conductivity of the composites. When filler volume fraction is 60vol%, the thermal conductivity of Al2O3-Sn57Bi43/epoxy composites is 2.95 W·(m·K)−1, 62.1% higher than that of Al2O3/epoxy composites (1.82 W·(m·K)−1). The results of Fogyel and Agari simulation demonstrate that the deposition of Sn57Bi43 on Al2O3 surface reduces the thermal contact resistance between fillers and forms thermally conductive networks more easily. The Al2O3-Sn57Bi43/epoxy composites exhibit higher dielectric loss, lower dielectric strength and volume resistivity than Al2O3/epoxy composites, still with electrical insulating properties. What is more, the tensile strength of the Al2O3-Sn57Bi43/epoxy composites is improved, because the improved interfacial properties of filler-matrix and the formed networks could transfer stress and prevent crack expansion.
2023, 40(11): 6119-6129.
doi: 10.13801/j.cnki.fhclxb.20230418.001
Abstract:
Carbon fiber is easily oxidized in a high-temperature oxygen-containing environment. The strong interfacial reactions with the matrix result in deterioration of their performance, which limits their use in carbon fiber-reinforced composites. In this paper, a C-Si3N4 protective coating which has high-temperature anti-oxidation performance was formed by constructing a polyacrylonitrile (PAN) layer and an organopolysilazane (OPSZ) layer on the surface of carbon fibers with curing at low-temperature and cracking at high-temperature. The results of scanning electron microscope and energy dispersive spectrometer show that the coating of PAN layer is helpful for Si element to adhere to the surface of carbon fiber. Increasing the concentration of the PAN solution from 1% to 3%, the relative content of the Si element increased from 2.81% to 8.26%. The tensile strength of PAN-OPSZ/carbon fiber prepared with PAN and OPSZ concentration of 3wt% was only 2.08% lower than that of uncoated carbon fiber, indicating that it did not cause obvious damage to the mechanical properties of carbon fiber. The oxidation resistance of the as-prepared PAN-OPSZ/carbon fibers was significantly improved, with a mass loss of less than 8wt% in an air atmosphere at 700℃, while the mass loss of uncoated carbon fibers was as high as 70wt%. The above results show that the PAN-OPSZ coating can effectively improve the high temperature oxidation resistance of carbon fibers, and has a very broad application prospect in the field of reinforced composites.
Carbon fiber is easily oxidized in a high-temperature oxygen-containing environment. The strong interfacial reactions with the matrix result in deterioration of their performance, which limits their use in carbon fiber-reinforced composites. In this paper, a C-Si3N4 protective coating which has high-temperature anti-oxidation performance was formed by constructing a polyacrylonitrile (PAN) layer and an organopolysilazane (OPSZ) layer on the surface of carbon fibers with curing at low-temperature and cracking at high-temperature. The results of scanning electron microscope and energy dispersive spectrometer show that the coating of PAN layer is helpful for Si element to adhere to the surface of carbon fiber. Increasing the concentration of the PAN solution from 1% to 3%, the relative content of the Si element increased from 2.81% to 8.26%. The tensile strength of PAN-OPSZ/carbon fiber prepared with PAN and OPSZ concentration of 3wt% was only 2.08% lower than that of uncoated carbon fiber, indicating that it did not cause obvious damage to the mechanical properties of carbon fiber. The oxidation resistance of the as-prepared PAN-OPSZ/carbon fibers was significantly improved, with a mass loss of less than 8wt% in an air atmosphere at 700℃, while the mass loss of uncoated carbon fibers was as high as 70wt%. The above results show that the PAN-OPSZ coating can effectively improve the high temperature oxidation resistance of carbon fibers, and has a very broad application prospect in the field of reinforced composites.
2023, 40(11): 6130-6138.
doi: 10.13801/j.cnki.fhclxb.20230222.010
Abstract:
Both pumice and nano hydrous iron oxide (NHFO) are commonly used adsorbents in water treatment. In this study, NHFO was loaded onto pumice by co-precipitation method to explore its adsorption performance and mechanism of ammonia nitrogen. The effects of initial ammonia concentration, initial pH value and co-existing ions (H+, Na+, K+, Mg2+) on NHFO@pumice adsorption of ammonia nitrogen were investigated. SEM-EDS and XRD were used to characterize the morphology and structure of NHFO@honeycomb. The results show that the initial concentration of ammonia nitrogen is 20 mg/L and the pH value is around 7. The co-existing ions have an inhibitory effect on the adsorption of ammonia nitrogen, and the inhibitory strength is H+>Na+>K+>Mg2+. SEM-EDS, XRD, FTIR and other characterization methods confirmed that NHFO was successfully loaded on the honeycomb, and the adsorption process was consistent with Langmuir adsorption isotherm (R2=0.9886) and quasi second-order kinetic model (R2=0.9969). The mechanism of ammonia nitrogen adsorption mainly includes electrostatic interaction of hydroxyl group and NH4+, ion exchange and pore adsorption. This study provides a theoretical basis for the treatment of ammonia-nitrogen water by adsorption.
Both pumice and nano hydrous iron oxide (NHFO) are commonly used adsorbents in water treatment. In this study, NHFO was loaded onto pumice by co-precipitation method to explore its adsorption performance and mechanism of ammonia nitrogen. The effects of initial ammonia concentration, initial pH value and co-existing ions (H+, Na+, K+, Mg2+) on NHFO@pumice adsorption of ammonia nitrogen were investigated. SEM-EDS and XRD were used to characterize the morphology and structure of NHFO@honeycomb. The results show that the initial concentration of ammonia nitrogen is 20 mg/L and the pH value is around 7. The co-existing ions have an inhibitory effect on the adsorption of ammonia nitrogen, and the inhibitory strength is H+>Na+>K+>Mg2+. SEM-EDS, XRD, FTIR and other characterization methods confirmed that NHFO was successfully loaded on the honeycomb, and the adsorption process was consistent with Langmuir adsorption isotherm (R2=0.9886) and quasi second-order kinetic model (R2=0.9969). The mechanism of ammonia nitrogen adsorption mainly includes electrostatic interaction of hydroxyl group and NH4+, ion exchange and pore adsorption. This study provides a theoretical basis for the treatment of ammonia-nitrogen water by adsorption.
2023, 40(11): 6139-6153.
doi: 10.13801/j.cnki.fhclxb.20230113.001
Abstract:
A large amount of uranium-containing wastewater produced in the nuclear industry circulation chain will cause damage to human health and ecological environment. Therefore, efficient treatment of uranium-containing wastewater is an important part of ensuring the sustainable development of the nuclear industry and human ecological security. Polyethyleneimine (PEI) functionalized composite aerogel (MGO/PEI) was synthesized by self-assembly of graphene oxide as a precursor and used to remove U(VI) from aqueous solution. The effects of different PEI dosage, stability, pH value, time, U(VI) concentration and temperature on the removal of U(VI) were investigated. The results showed that the adsorption behavior was accorded with the pseudo-second-order kinetic model and the Langmuir isothermal adsorption model at 298 K and pH=6, and the maximum adsorption capacity was 1027.01 mg·g−1. The thermodynamic constants indicated that the adsorption of U(VI) by MGO/PEI was a spontaneous endothermic process. XPS analysis showed that the removal mechanism was mainly due to the surface complexation of amino and oxygen-containing functional groups with U(VI).
A large amount of uranium-containing wastewater produced in the nuclear industry circulation chain will cause damage to human health and ecological environment. Therefore, efficient treatment of uranium-containing wastewater is an important part of ensuring the sustainable development of the nuclear industry and human ecological security. Polyethyleneimine (PEI) functionalized composite aerogel (MGO/PEI) was synthesized by self-assembly of graphene oxide as a precursor and used to remove U(VI) from aqueous solution. The effects of different PEI dosage, stability, pH value, time, U(VI) concentration and temperature on the removal of U(VI) were investigated. The results showed that the adsorption behavior was accorded with the pseudo-second-order kinetic model and the Langmuir isothermal adsorption model at 298 K and pH=6, and the maximum adsorption capacity was 1027.01 mg·g−1. The thermodynamic constants indicated that the adsorption of U(VI) by MGO/PEI was a spontaneous endothermic process. XPS analysis showed that the removal mechanism was mainly due to the surface complexation of amino and oxygen-containing functional groups with U(VI).
2023, 40(11): 6154-6162.
doi: 10.13801/j.cnki.fhclxb.20230217.003
Abstract:
With the increasing development of industrial production, the demand for gas sensors is growing. Given that triethylamine is easily harmful to the human body, it is important to develop a gas sensor that can effectively detect triethylamine. Considering the shortcomings of common gas sensors with high working temperature and high energy consumption, a gas sensing material that can quickly detect triethylamine at room temperature was proposed in this paper. Through the combination of electrospinning, heat treatment and in-situ chemical oxidation polymerization, the inorganic-organic composite, WO3@polyaniline (PANI) nanofibers, was successfully synthesized with controllable component content. Scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectrometer and Fourier transform infrared spectroscopy were used to characterize the morphology, element content and functional groups of the as-prepared samples. The composite demonstrates fibrous morphology with PANI uniformly distributed on the surface of WO3 nanofibers, forming WO3@PANI core-shell structure. The WO3@PANI composite nanofibers show good sensing performance to triethylamine at room temperature. In addition, excellent sensing properties are also achieved, such as excellent triethylamine selectivity, stable response under high humidity condition, wide concentration detection range (50-5000 μg/g triethylamine) and good response-recovery characteristics. Compared with sensing performance of pristine PANI and WO3 nanofibers, the enhanced sensing response of WO3@PANI composite nanofibers is mainly attributed to the p-n heterojunction formed between WO3 and PANI.
With the increasing development of industrial production, the demand for gas sensors is growing. Given that triethylamine is easily harmful to the human body, it is important to develop a gas sensor that can effectively detect triethylamine. Considering the shortcomings of common gas sensors with high working temperature and high energy consumption, a gas sensing material that can quickly detect triethylamine at room temperature was proposed in this paper. Through the combination of electrospinning, heat treatment and in-situ chemical oxidation polymerization, the inorganic-organic composite, WO3@polyaniline (PANI) nanofibers, was successfully synthesized with controllable component content. Scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectrometer and Fourier transform infrared spectroscopy were used to characterize the morphology, element content and functional groups of the as-prepared samples. The composite demonstrates fibrous morphology with PANI uniformly distributed on the surface of WO3 nanofibers, forming WO3@PANI core-shell structure. The WO3@PANI composite nanofibers show good sensing performance to triethylamine at room temperature. In addition, excellent sensing properties are also achieved, such as excellent triethylamine selectivity, stable response under high humidity condition, wide concentration detection range (50-5000 μg/g triethylamine) and good response-recovery characteristics. Compared with sensing performance of pristine PANI and WO3 nanofibers, the enhanced sensing response of WO3@PANI composite nanofibers is mainly attributed to the p-n heterojunction formed between WO3 and PANI.
2023, 40(11): 6163-6172.
doi: 10.13801/j.cnki.fhclxb.20230105.003
Abstract:
Molybdenum disulfide (MoS2) is easy to be oxidized when used at high temperature, which leads to significant deterioration of its tribological properties, showing a high friction coefficient. In order to improve the tribological properties of MoS2 lubricant under high temperature environment, core-shell MoS2@SiO2 nanocomposites was formed by hydrothermal method and improved Stöber method. The morphology, size and composition of the nano materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The micro results show that the core-shell structure composite is successfully prepared, with an average particle size of 250 nm. The high temperature friction test of prepared MoS2@SiO2 solid lubrication coating was carried out, and the MoS2 coating was used as a comparison. The morphology and structure of the coating were characterized by SEM and XRD, and the wear rate of the coating was characterized by a 3D profiler. The results show that the friction coefficient of the MoS2@SiO2 coating at 680℃ is 0.2 and relatively stable, while MoS2 coating rapidly fail. The MoS2@SiO2 coating had better wear resistance, with a wear rate at 25.86%, lower than that of MoS2 coating. After the friction tests, MoS2 still existed in the wear scar area of the MoS2@SiO2 coating, which was covered by the lubricating film. However, the substrate in the wear zone of MoS2 coating was completely exposed. It is thus shown that the encapsulation of the SiO2 shell retards the rapid oxidation of MoS2 at high temperatures and the two synergistically lubricate to prolong the service life of the coating.
Molybdenum disulfide (MoS2) is easy to be oxidized when used at high temperature, which leads to significant deterioration of its tribological properties, showing a high friction coefficient. In order to improve the tribological properties of MoS2 lubricant under high temperature environment, core-shell MoS2@SiO2 nanocomposites was formed by hydrothermal method and improved Stöber method. The morphology, size and composition of the nano materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The micro results show that the core-shell structure composite is successfully prepared, with an average particle size of 250 nm. The high temperature friction test of prepared MoS2@SiO2 solid lubrication coating was carried out, and the MoS2 coating was used as a comparison. The morphology and structure of the coating were characterized by SEM and XRD, and the wear rate of the coating was characterized by a 3D profiler. The results show that the friction coefficient of the MoS2@SiO2 coating at 680℃ is 0.2 and relatively stable, while MoS2 coating rapidly fail. The MoS2@SiO2 coating had better wear resistance, with a wear rate at 25.86%, lower than that of MoS2 coating. After the friction tests, MoS2 still existed in the wear scar area of the MoS2@SiO2 coating, which was covered by the lubricating film. However, the substrate in the wear zone of MoS2 coating was completely exposed. It is thus shown that the encapsulation of the SiO2 shell retards the rapid oxidation of MoS2 at high temperatures and the two synergistically lubricate to prolong the service life of the coating.
2023, 40(11): 6173-6181.
doi: 10.13801/j.cnki.fhclxb.20230112.004
Abstract:
Dielectric polymers have drawn great interest due to their applications in energy harvesting/storage devices, sensors and actuators owing to the merits of high breakdown strength, good flexibility, easy processing and low cost. However, how to achieve the combination of high dielectric constant and low dielectric loss is still an important scientific problem to be solved in this field. Therefore, based on a strategy of "bridges" effect between filler and matrix, this work prepared the epoxidized natural rubber (ENR) based dielectric composites (P-rGO/ENR) with segregated structure through latex blending and in-situ hot pressing reduction, using graphene oxide (GO) as filler, ENR latex as the matrix, and phytic acid (PA) as a modifying agent. The results show that PA can “bridge” GO and ENR by ring-opening reactions, respectively. As a result, the interfacial interaction between GO and ENR can be greatly enhanced. At the same time, the ENR latex particles force the GO nanosheets into the interstitial space between them because the ENR latex particles act as an excluded volume. As a result, GO nanosheets are self-assembled and coated on the surface of ENR latex microspheres. Finally, during the drying or co-coagulation procedure, these GO-coated ENR latex microspheres connect with each other to form a continuous three-dimensional segregated structure. The dielectric constant of the P-rGO/ENR composite (2wt%GO), is as high as 569903 and the conductivity is 10−4 S/cm as well as maintains a low dielectric loss (<5) at 100 Hz.
Dielectric polymers have drawn great interest due to their applications in energy harvesting/storage devices, sensors and actuators owing to the merits of high breakdown strength, good flexibility, easy processing and low cost. However, how to achieve the combination of high dielectric constant and low dielectric loss is still an important scientific problem to be solved in this field. Therefore, based on a strategy of "bridges" effect between filler and matrix, this work prepared the epoxidized natural rubber (ENR) based dielectric composites (P-rGO/ENR) with segregated structure through latex blending and in-situ hot pressing reduction, using graphene oxide (GO) as filler, ENR latex as the matrix, and phytic acid (PA) as a modifying agent. The results show that PA can “bridge” GO and ENR by ring-opening reactions, respectively. As a result, the interfacial interaction between GO and ENR can be greatly enhanced. At the same time, the ENR latex particles force the GO nanosheets into the interstitial space between them because the ENR latex particles act as an excluded volume. As a result, GO nanosheets are self-assembled and coated on the surface of ENR latex microspheres. Finally, during the drying or co-coagulation procedure, these GO-coated ENR latex microspheres connect with each other to form a continuous three-dimensional segregated structure. The dielectric constant of the P-rGO/ENR composite (2wt%GO), is as high as 569903 and the conductivity is 10−4 S/cm as well as maintains a low dielectric loss (<5) at 100 Hz.
Performance study of Fe(III)-doped BiOCl photocatalyst for degradation of tetracycline hydrochloride
2023, 40(11): 6182-6193.
doi: 10.13801/j.cnki.fhclxb.20230117.002
Abstract:
Tetracycline hydrochloride (TC-HCl), which can be released into the aquatic environment through excreta, poses a potential threat to aquatic systems and human health due to its stable structure and difficult biodegradability. As one of the photocatalytic materials of great interest, BiOCl development applications are limited by the low solar light utilization and the hight rate of photogenerated electron-hole recombination. In this study, Fe-doped BiOCl porous microspheres self-assembled from two-dimensional nanosbeets were synthesized by a one-pot solvothermal method without the addition of surfactants, and the degradation properties for TC-HCl was investigated. The results showed that Fe doping narrowed the forbidden band width of BiOCl, thereby improving the light absorption intensity and broadening the photoresponse range to the visible region. Fe doping accelerated the separation of photogenerated carriers and improved the photocatalytic performance of BiOCl. The 0.15-Fe/BiOCl had the best removal effect on TC-HCl (30 mg/L), and the removal rate could reach 92% after dark adsorption and photocatalysis. Combined with the experimental results, the mechanism of photocatalytic degradation of TC-HCl by Fe-doped BiOCl under visible light is revealed in this study, and the reasons for the reduction of cycling activity are analyzed, which provides a promising method for the preparation of transition metal-doped BiOCl materials with high photocatalytic activity and feasible insights for improving the cycling activity of materials.
Tetracycline hydrochloride (TC-HCl), which can be released into the aquatic environment through excreta, poses a potential threat to aquatic systems and human health due to its stable structure and difficult biodegradability. As one of the photocatalytic materials of great interest, BiOCl development applications are limited by the low solar light utilization and the hight rate of photogenerated electron-hole recombination. In this study, Fe-doped BiOCl porous microspheres self-assembled from two-dimensional nanosbeets were synthesized by a one-pot solvothermal method without the addition of surfactants, and the degradation properties for TC-HCl was investigated. The results showed that Fe doping narrowed the forbidden band width of BiOCl, thereby improving the light absorption intensity and broadening the photoresponse range to the visible region. Fe doping accelerated the separation of photogenerated carriers and improved the photocatalytic performance of BiOCl. The 0.15-Fe/BiOCl had the best removal effect on TC-HCl (30 mg/L), and the removal rate could reach 92% after dark adsorption and photocatalysis. Combined with the experimental results, the mechanism of photocatalytic degradation of TC-HCl by Fe-doped BiOCl under visible light is revealed in this study, and the reasons for the reduction of cycling activity are analyzed, which provides a promising method for the preparation of transition metal-doped BiOCl materials with high photocatalytic activity and feasible insights for improving the cycling activity of materials.
2023, 40(11): 6194-6201.
doi: 10.13801/j.cnki.fhclxb.20230120.001
Abstract:
Transition metal-based electrocatalysts with abundant reserves and low cost have been widely studied as potential substitutes for efficient oxygen evolution reaction (OER) precious metal electrocatalysts, but there are still problems of poor activity and conductivity. Here, a nitrogen-doped carbon (NC) supported CoWO4 (CoWO4/NC) catalyst with abundant oxygen vacancy was prepared by the pyrolysis of W/Co-ZIF precursor. The feeding ratio and calcination temperature of the catalyst were explored. OER performance in alkaline medium was tested. The test results show that the catalyst prepared at a feeding ratio of 1∶1 and a calcination temperature of 550℃ exhibits a low overpotential (346 mV at current density of 10 mA·cm−2), a low Tafel slope (65 mV·dec−1) and a high conductivity. The stability of the catalyst under alkaline conditions was tested by the timing potential method. The performance does not degrade significantly within 22 h. This work provides a new idea for the research of transition metal-based catalyst and has certain guiding significance for the design of catalyst.
Transition metal-based electrocatalysts with abundant reserves and low cost have been widely studied as potential substitutes for efficient oxygen evolution reaction (OER) precious metal electrocatalysts, but there are still problems of poor activity and conductivity. Here, a nitrogen-doped carbon (NC) supported CoWO4 (CoWO4/NC) catalyst with abundant oxygen vacancy was prepared by the pyrolysis of W/Co-ZIF precursor. The feeding ratio and calcination temperature of the catalyst were explored. OER performance in alkaline medium was tested. The test results show that the catalyst prepared at a feeding ratio of 1∶1 and a calcination temperature of 550℃ exhibits a low overpotential (346 mV at current density of 10 mA·cm−2), a low Tafel slope (65 mV·dec−1) and a high conductivity. The stability of the catalyst under alkaline conditions was tested by the timing potential method. The performance does not degrade significantly within 22 h. This work provides a new idea for the research of transition metal-based catalyst and has certain guiding significance for the design of catalyst.
2023, 40(11): 6202-6216.
doi: 10.13801/j.cnki.fhclxb.20230117.008
Abstract:
3D printing technology provides multi-scale, multi-material and multi-dimensional manufacturing capability for microwave absorber, which is beneficial to take advantage of the combination of material loss and structural loss. In this work, a three-layer periodic crisscrossed structural microwave absorber was fabricated by using FeSiAl-MoS2-graphene (GN)/polylactic acid (PLA) composite filaments, and the effects of the geometric parameters of the unit cell and the combination of materials of each layer on the absorption performance of the complex structural absorber were investigated. The effective absorption bandwidth (EAB, for reflection loss RL≤−10 dB) of the absorber was 12.7 GHz when the graphene content of dielectric layer, absorption layer and matching layer was 0wt%, 5wt% and 4wt% in turn. At the same time, the EAB value were greater than 10 GHz when the incident angles of transverse electric wave (TE polarized wave) and transverse magnetic wave (TM polarized wave) were less than 40° and 70°, respectively. This study provides a theoretical and applied basis for the design and manufacture of wide-angle and broadband wave absorbers due to the experimental results are basically consistent with the simulation results.
3D printing technology provides multi-scale, multi-material and multi-dimensional manufacturing capability for microwave absorber, which is beneficial to take advantage of the combination of material loss and structural loss. In this work, a three-layer periodic crisscrossed structural microwave absorber was fabricated by using FeSiAl-MoS2-graphene (GN)/polylactic acid (PLA) composite filaments, and the effects of the geometric parameters of the unit cell and the combination of materials of each layer on the absorption performance of the complex structural absorber were investigated. The effective absorption bandwidth (EAB, for reflection loss RL≤−10 dB) of the absorber was 12.7 GHz when the graphene content of dielectric layer, absorption layer and matching layer was 0wt%, 5wt% and 4wt% in turn. At the same time, the EAB value were greater than 10 GHz when the incident angles of transverse electric wave (TE polarized wave) and transverse magnetic wave (TM polarized wave) were less than 40° and 70°, respectively. This study provides a theoretical and applied basis for the design and manufacture of wide-angle and broadband wave absorbers due to the experimental results are basically consistent with the simulation results.
2023, 40(11): 6217-6227.
doi: 10.13801/j.cnki.fhclxb.20230215.002
Abstract:
In order to meet the requirements for better and more diversified performance of lithium-ion batteries, electrode materials for improving battery performance were studied. Among many electrode materials, vanadium-based materials are suitable for lithium-ion battery electrode materials due to their rich valence changes and various types. Magnesium vanadate (MgV2O6)-sodium vanadate (NaV6O15) composites on titanium foil were synthesized by ion exchange method using sodium vanadate nanowar arrays as precursors. After calcination in air, the temperature was 300℃ and 500℃, respectively. With the increase of the calcination temperature, the diameter of the nanowires became larger. The crystal structure, chemical composition and microstructure of the prepared samples were characterized in detail. Among them, the magnesium vanadate and sodium vanadate composite prepared by calcination at 300℃ had better electrochemical lithium storage performance. The first discharge capacity was 1144 mA·h·g−1 at the current density of 50 mA·g−1, and the specific discharge capacity was still 837 mA·h·g−1 after 100 cycles, showing good cycling stability. Compared with sodium vanadate precursor, the lithium storage performance was significantly improved. It provides a new idea for the application of alkaline earth vanadate synthesized by magnesium ions in the field of electrochemical energy storage.
In order to meet the requirements for better and more diversified performance of lithium-ion batteries, electrode materials for improving battery performance were studied. Among many electrode materials, vanadium-based materials are suitable for lithium-ion battery electrode materials due to their rich valence changes and various types. Magnesium vanadate (MgV2O6)-sodium vanadate (NaV6O15) composites on titanium foil were synthesized by ion exchange method using sodium vanadate nanowar arrays as precursors. After calcination in air, the temperature was 300℃ and 500℃, respectively. With the increase of the calcination temperature, the diameter of the nanowires became larger. The crystal structure, chemical composition and microstructure of the prepared samples were characterized in detail. Among them, the magnesium vanadate and sodium vanadate composite prepared by calcination at 300℃ had better electrochemical lithium storage performance. The first discharge capacity was 1144 mA·h·g−1 at the current density of 50 mA·g−1, and the specific discharge capacity was still 837 mA·h·g−1 after 100 cycles, showing good cycling stability. Compared with sodium vanadate precursor, the lithium storage performance was significantly improved. It provides a new idea for the application of alkaline earth vanadate synthesized by magnesium ions in the field of electrochemical energy storage.
2023, 40(11): 6228-6240.
doi: 10.13801/j.cnki.fhclxb.20230217.001
Abstract:
Flexible tactile sensors have broad application potential in electronic skin, intelligent robots, wearable electronic devices, and medical health. To solve the problems of low sensitivity and poor response/recovery performance of piezoresistive flexible tactile sensor, a near-field electrohydrodynamic direct-writing method was proposed to fabricate flexible tactile sensor based on cellulose acetate (CA)/MXene multilayer nano sheet composite fiber thin film, in which MXene nano sheets were assembled into a continuous three-dimensional (3D) conductive network with porous structure using cellulose acetate fiber with porous structure as a bridge agent. Compared with the traditional fabrication method of flexible tactile sensor, this method effectively improved the electrical performance of CA/MXene composite fiber thin film through the action of high-voltage electrostatic field, which improved the sensing performance of flexible tactile sensor. The test results show that the flexible tactile pressure sensing range of the flexible tactile sensor is 9 Pa-10.2 kPa. Within the pressure range of 9 Pa-5.6 kPa, the sensitivity of the sensor is 17.36 kPa−1, and it has fast response/recovery performance (60.31/74.35 ms). The experimental results show that the fabricated flexible tactile sensor can recognize the changes of finger motion state, respiration state, and pulse signal, which has broad application prospects in human motion detection and physiological signal monitoring.
Flexible tactile sensors have broad application potential in electronic skin, intelligent robots, wearable electronic devices, and medical health. To solve the problems of low sensitivity and poor response/recovery performance of piezoresistive flexible tactile sensor, a near-field electrohydrodynamic direct-writing method was proposed to fabricate flexible tactile sensor based on cellulose acetate (CA)/MXene multilayer nano sheet composite fiber thin film, in which MXene nano sheets were assembled into a continuous three-dimensional (3D) conductive network with porous structure using cellulose acetate fiber with porous structure as a bridge agent. Compared with the traditional fabrication method of flexible tactile sensor, this method effectively improved the electrical performance of CA/MXene composite fiber thin film through the action of high-voltage electrostatic field, which improved the sensing performance of flexible tactile sensor. The test results show that the flexible tactile pressure sensing range of the flexible tactile sensor is 9 Pa-10.2 kPa. Within the pressure range of 9 Pa-5.6 kPa, the sensitivity of the sensor is 17.36 kPa−1, and it has fast response/recovery performance (60.31/74.35 ms). The experimental results show that the fabricated flexible tactile sensor can recognize the changes of finger motion state, respiration state, and pulse signal, which has broad application prospects in human motion detection and physiological signal monitoring.
2023, 40(11): 6241-6250.
doi: 10.13801/j.cnki.fhclxb.20230113.002
Abstract:
Highly efficient, stable cathode is crucial to lithium-oxygen battery. A high performance, integrated Au-N-CNT/SS cathode with interpermeable channels was constructed by chemical vapor deposition and photoreduction, in which the high catalytic Au nanoparticles were loaded on nitrogen doped carbon nanotubes (N-CNT) with three-dimensional penetrating sturctured stainless steel (SS) mesh. The morphology and composition of the Au-N-CNT/SS were investigated by SEM, TEM, XPS, XRD and Raman spectrum. The problems of poor mechanical stability, carbonaceous cathode decomposition and serious side reactions were avoided by the suitable channel structure, high conductivity, superior mechanical properties, structural stability of Au-N-CNT/SS. Taking Au-N-CNT/SS as the integrated cathode for lithium-oxygen battery, the utilization of binder is avoided. The mechanical strength of the lithium-oxygen battery is enhanced, and the side reactions are effectively reduced, contributing to the enhanced electrochemical/chemical stability. The high conductivity, interpenetrated structure and sufficient pores provide a fast electron transport and mass transfer channel. The highly efficient Au nanoparticles are favorable to improving the oxygen reduction/oxygen evolution reaction kinetics on cathode, accelerating the generation and decomposition of discharge products. The rate performance (keeping the discharge voltage at 2.4 V with a high current density of 1.0 mA·cm−2), specific capacity (8.47 mA·h·cm−2) and cycle performance (160 cycles) of lithium-oxygen battery are greatly improved.
Highly efficient, stable cathode is crucial to lithium-oxygen battery. A high performance, integrated Au-N-CNT/SS cathode with interpermeable channels was constructed by chemical vapor deposition and photoreduction, in which the high catalytic Au nanoparticles were loaded on nitrogen doped carbon nanotubes (N-CNT) with three-dimensional penetrating sturctured stainless steel (SS) mesh. The morphology and composition of the Au-N-CNT/SS were investigated by SEM, TEM, XPS, XRD and Raman spectrum. The problems of poor mechanical stability, carbonaceous cathode decomposition and serious side reactions were avoided by the suitable channel structure, high conductivity, superior mechanical properties, structural stability of Au-N-CNT/SS. Taking Au-N-CNT/SS as the integrated cathode for lithium-oxygen battery, the utilization of binder is avoided. The mechanical strength of the lithium-oxygen battery is enhanced, and the side reactions are effectively reduced, contributing to the enhanced electrochemical/chemical stability. The high conductivity, interpenetrated structure and sufficient pores provide a fast electron transport and mass transfer channel. The highly efficient Au nanoparticles are favorable to improving the oxygen reduction/oxygen evolution reaction kinetics on cathode, accelerating the generation and decomposition of discharge products. The rate performance (keeping the discharge voltage at 2.4 V with a high current density of 1.0 mA·cm−2), specific capacity (8.47 mA·h·cm−2) and cycle performance (160 cycles) of lithium-oxygen battery are greatly improved.
A bismuth-rich Bi4O5Br2/TiO2 composites fibers photocatalyst enables dramatic CO2 reduction activity
2023, 40(11): 6251-6259.
doi: 10.13801/j.cnki.fhclxb.20230222.004
Abstract:
Photocatalytic reduction technology of CO2 can not only achieve energy saving and emission reduction, but also alleviate energy shortage, which is in line with today's concept of green and sustainable development. By employing electrospun TiO2 nanofibers as substrate, bismuth-rich Bi4O5Br2/TiO2 composite fibers were prepared combining with in-situ hydrothermal reduction method. The composition, morphology and photoelectric properties were characterized by XRD, SEM, HRTEM, XPS, UV-Vis and carbon adsorption. The results show that the band gap of Bi4O5Br2/TiO2 composite fibers becomes width, there is obvious absorption in the visible light band, and the reduction ability of photogenerated electrons is enhanced. Bi4O5Br2/TiO2 composite fibers can reduce CO2 to CH4 and CO, while the enrichment of the metal Bi can not only improve the adsorption capacity of the catalyst for acidic CO2 molecules and enhance the conversion efficiency, but also change the photocatalytic reaction path and generate alcohol products such as CH3OH. The CH4, CO and CH3OH yields of the optimized photocatalyst Bi@Bi4O5Br2/TiO2 composite fibers were 3.87, 1.06 and 0.32 μmol·h−1·g−1, respectively, after simulated sunlight irradiation 3 h. This work provides new opportunities for exploring high-efficiency CO2 photoreduction catalysts.
Photocatalytic reduction technology of CO2 can not only achieve energy saving and emission reduction, but also alleviate energy shortage, which is in line with today's concept of green and sustainable development. By employing electrospun TiO2 nanofibers as substrate, bismuth-rich Bi4O5Br2/TiO2 composite fibers were prepared combining with in-situ hydrothermal reduction method. The composition, morphology and photoelectric properties were characterized by XRD, SEM, HRTEM, XPS, UV-Vis and carbon adsorption. The results show that the band gap of Bi4O5Br2/TiO2 composite fibers becomes width, there is obvious absorption in the visible light band, and the reduction ability of photogenerated electrons is enhanced. Bi4O5Br2/TiO2 composite fibers can reduce CO2 to CH4 and CO, while the enrichment of the metal Bi can not only improve the adsorption capacity of the catalyst for acidic CO2 molecules and enhance the conversion efficiency, but also change the photocatalytic reaction path and generate alcohol products such as CH3OH. The CH4, CO and CH3OH yields of the optimized photocatalyst Bi@Bi4O5Br2/TiO2 composite fibers were 3.87, 1.06 and 0.32 μmol·h−1·g−1, respectively, after simulated sunlight irradiation 3 h. This work provides new opportunities for exploring high-efficiency CO2 photoreduction catalysts.
2023, 40(11): 6260-6274.
doi: 10.13801/j.cnki.fhclxb.20230222.002
Abstract:
In order to study the influence of the short steel fiber on the mechanical properties of carbon textile reinforced concrete (C-TRC) under low-cycle fatigue loading, low-cycle fatigue loading test and quasi-static tensile tests before and after fatigue loading were conducted on specimens with various contents of short steel fiber (0vol%, 0.5vol% and 1.0vol%) by a universal testing machine, and distributions of crack and strain were obtained by digital image correlation (DIC) method. The results show that the addition of short steel fiber can increase the tensile strength, the Young’s modulus and toughness of C-TRC, reduce the energy dissipation and residual accumulated strain and increase the crack number and crack width. Fatigue load can reduce the rigidity, tensile strength, peak strain, and toughness, and accelerate the destruction of C-TRC. The addition of short steel fiber can reduce the property degradation caused by fatigue loading, and the 0.5vol% addition has the best enhancement effect. The strength degradation model was modified based on the existing residual strength-residual stiffness coupled model and experimental data, The modified model is used to fit the experimental data and be compared with the existing model. The results show that the modified model is more consistent with the experimental data. These findings will be available for the fatigue performance evaluation of textile reinforced concrete (TRC).
In order to study the influence of the short steel fiber on the mechanical properties of carbon textile reinforced concrete (C-TRC) under low-cycle fatigue loading, low-cycle fatigue loading test and quasi-static tensile tests before and after fatigue loading were conducted on specimens with various contents of short steel fiber (0vol%, 0.5vol% and 1.0vol%) by a universal testing machine, and distributions of crack and strain were obtained by digital image correlation (DIC) method. The results show that the addition of short steel fiber can increase the tensile strength, the Young’s modulus and toughness of C-TRC, reduce the energy dissipation and residual accumulated strain and increase the crack number and crack width. Fatigue load can reduce the rigidity, tensile strength, peak strain, and toughness, and accelerate the destruction of C-TRC. The addition of short steel fiber can reduce the property degradation caused by fatigue loading, and the 0.5vol% addition has the best enhancement effect. The strength degradation model was modified based on the existing residual strength-residual stiffness coupled model and experimental data, The modified model is used to fit the experimental data and be compared with the existing model. The results show that the modified model is more consistent with the experimental data. These findings will be available for the fatigue performance evaluation of textile reinforced concrete (TRC).
2023, 40(11): 6275-6287.
doi: 10.13801/j.cnki.fhclxb.20230203.002
Abstract:
Nano-silica (NS) modified asphalt is satisfactory in mechanical properties but is expensive. Fumed-silica (FS) is also a nanoscale material and the price is only 1/10 of NS. To evaluate the feasibility of FS replacing NS, using 3wt% original silica (OS), FS, hydrophobic nano silica (MNS) as modifier, the rheological properties of corresponding modified asphalt were studied compared with matrix asphalt (Esso, ES) by the multi-stress creep recovery test (MSCR), linear amplitude scanning test (LAS) and bent beam rheological test (BBR). The results show that the optimal modifier FS has the best effect on the rutting resistance at high temperature and the fatigue resistance at intermediate temperature for asphalt, and the least negative effect on the low temperature performance. The mechanism for these results was explored by SEM, temperature scanning test (TeS), variable temperature infrared spectroscopy (VT-IR), TGA and DSC. The intrinsic primary aggregates of FS and unique ES-hydroclusters system played a key role in the performance of FS-asphalt composite. Therefore, fumed SiO2 is a cost-effective nano-scale material used to modify asphalt.
Nano-silica (NS) modified asphalt is satisfactory in mechanical properties but is expensive. Fumed-silica (FS) is also a nanoscale material and the price is only 1/10 of NS. To evaluate the feasibility of FS replacing NS, using 3wt% original silica (OS), FS, hydrophobic nano silica (MNS) as modifier, the rheological properties of corresponding modified asphalt were studied compared with matrix asphalt (Esso, ES) by the multi-stress creep recovery test (MSCR), linear amplitude scanning test (LAS) and bent beam rheological test (BBR). The results show that the optimal modifier FS has the best effect on the rutting resistance at high temperature and the fatigue resistance at intermediate temperature for asphalt, and the least negative effect on the low temperature performance. The mechanism for these results was explored by SEM, temperature scanning test (TeS), variable temperature infrared spectroscopy (VT-IR), TGA and DSC. The intrinsic primary aggregates of FS and unique ES-hydroclusters system played a key role in the performance of FS-asphalt composite. Therefore, fumed SiO2 is a cost-effective nano-scale material used to modify asphalt.
2023, 40(11): 6288-6298.
doi: 10.13801/j.cnki.fhclxb.20230111.001
Abstract:
The purpose is to reveal the deterioration law of mechanical properties for elastomer composites at different service environments and promote their popularization and application in the field of solvent-free coatings. Ultra high molecular weight polyethylene/elastomer (UHMWPE/EL) composites were prepared. Application environments such as hydrothermal aging, low-temperature embrittlement and climate aging were simulated, and the evolution process and laws of various mechanical properties for elastomer and its composites at different environments were studied. The damage status of shape auto restore ability for composites at different deformations and temperatures was evaluated. Finally, the durability and environmental adaptability of composites were proved. The results show that after continuous exposure for 7 days or 81 h at different application environments, the retention rates of mechanical properties for UHMWPE/EL composites are more than 90%, which meet the requirements of specifications. And the mechanical properties of composites decrease 15%-20% after being exposed to hygrothermal environment, cold environment and weathering environment for 30 days. The composites have obvious thermal stability and automatic shape recovery ability, and the recovery rates at different deformation modes of tension, bending and torsion are over 90%.
The purpose is to reveal the deterioration law of mechanical properties for elastomer composites at different service environments and promote their popularization and application in the field of solvent-free coatings. Ultra high molecular weight polyethylene/elastomer (UHMWPE/EL) composites were prepared. Application environments such as hydrothermal aging, low-temperature embrittlement and climate aging were simulated, and the evolution process and laws of various mechanical properties for elastomer and its composites at different environments were studied. The damage status of shape auto restore ability for composites at different deformations and temperatures was evaluated. Finally, the durability and environmental adaptability of composites were proved. The results show that after continuous exposure for 7 days or 81 h at different application environments, the retention rates of mechanical properties for UHMWPE/EL composites are more than 90%, which meet the requirements of specifications. And the mechanical properties of composites decrease 15%-20% after being exposed to hygrothermal environment, cold environment and weathering environment for 30 days. The composites have obvious thermal stability and automatic shape recovery ability, and the recovery rates at different deformation modes of tension, bending and torsion are over 90%.
2023, 40(11): 6299-6310.
doi: 10.13801/j.cnki.fhclxb.20230222.006
Abstract:
To solve the problems such as poor compatibility with the cementitious matrix and high cost of current bacterial carriers, a type of self-healing concrete by immobilizing non-axenic bacteria into recycled aggregate (RA) with enhancement was proposed. The reasonable enhancement time of RA and its effect on the compressive strength of concrete were first investigated. Then, the crack-healing capacity and the crack-filling precipitations of concrete immobilizing non-axenic bacteria were studied. The test results show that the reasonable enhancement time of the RA using biodeposition of non-axenic bacteria is 7 days. The water absorption and crushing index of recycled coarse aggregate (RCA) decrease by 27% and 20%, respectively. The compressive strength of concrete prepared with the enhanced RCA increases by 12.9%. After 28 days of healing, the average values of healed crack widths and completely healed percentages of cracks of the concrete specimens by immobilizing non-axenic bacteria into RA with enhancement are up to 0.28 mm and 60%. The maximum width value of healed cracks reaches 1.26 mm. The water permeability coefficients of the concrete specimens can decrease by up to 99.7% compared to that without crack-healing. The crack-filling precipitations of self-healing concrete by immobilizing non-axenic bacteria exhibit regular cubic shapes. The crystals of these precipitations are calcite.
To solve the problems such as poor compatibility with the cementitious matrix and high cost of current bacterial carriers, a type of self-healing concrete by immobilizing non-axenic bacteria into recycled aggregate (RA) with enhancement was proposed. The reasonable enhancement time of RA and its effect on the compressive strength of concrete were first investigated. Then, the crack-healing capacity and the crack-filling precipitations of concrete immobilizing non-axenic bacteria were studied. The test results show that the reasonable enhancement time of the RA using biodeposition of non-axenic bacteria is 7 days. The water absorption and crushing index of recycled coarse aggregate (RCA) decrease by 27% and 20%, respectively. The compressive strength of concrete prepared with the enhanced RCA increases by 12.9%. After 28 days of healing, the average values of healed crack widths and completely healed percentages of cracks of the concrete specimens by immobilizing non-axenic bacteria into RA with enhancement are up to 0.28 mm and 60%. The maximum width value of healed cracks reaches 1.26 mm. The water permeability coefficients of the concrete specimens can decrease by up to 99.7% compared to that without crack-healing. The crack-filling precipitations of self-healing concrete by immobilizing non-axenic bacteria exhibit regular cubic shapes. The crystals of these precipitations are calcite.
2023, 40(11): 6311-6323.
doi: 10.13801/j.cnki.fhclxb.20230222.008
Abstract:
For the corrosion and wear failure of materials used in the marine environment, the (CrFeNiAl)100–xMox high-entropy alloy coatings were prepared on 304 stainless steel (304 ss) by laser cladding. The phase composition, microstructure, hardness, wear resistance and corrosion resistance of the coatings were analyzed. The results show that the coatings are composed of body-centered cubic (BCC)+B2 phases. With the increase of Mo, the content of B2 phase gradually increases, and nano scale B2 phase precipitates in the dendrite. The hardness of the coating increases with the increase of Mo content, the highest hardness reaches HV0.2 636.6, and the wear resistance increases gradually. The corrosion current density firstly decreases and then increases with the increase of Mo, indicating that the corrosion resistance of the coating firstly increases and then decreases in 3.5wt%NaCl solution. The results of immersion corrosion show that the coatings are selectively dissolved in the interdendritic region. The corrosion current density and passivation current density of (CrFeNiAl)92Mo8 coating are lower than 304 ss, and the corrosion resistance is the best with good wear resistance. Adding appropriate Mo element can improve the wear resistance and corrosion resistance of (CrFeNiAl)100–xMox coatings.
For the corrosion and wear failure of materials used in the marine environment, the (CrFeNiAl)100–xMox high-entropy alloy coatings were prepared on 304 stainless steel (304 ss) by laser cladding. The phase composition, microstructure, hardness, wear resistance and corrosion resistance of the coatings were analyzed. The results show that the coatings are composed of body-centered cubic (BCC)+B2 phases. With the increase of Mo, the content of B2 phase gradually increases, and nano scale B2 phase precipitates in the dendrite. The hardness of the coating increases with the increase of Mo content, the highest hardness reaches HV0.2 636.6, and the wear resistance increases gradually. The corrosion current density firstly decreases and then increases with the increase of Mo, indicating that the corrosion resistance of the coating firstly increases and then decreases in 3.5wt%NaCl solution. The results of immersion corrosion show that the coatings are selectively dissolved in the interdendritic region. The corrosion current density and passivation current density of (CrFeNiAl)92Mo8 coating are lower than 304 ss, and the corrosion resistance is the best with good wear resistance. Adding appropriate Mo element can improve the wear resistance and corrosion resistance of (CrFeNiAl)100–xMox coatings.
2023, 40(11): 6324-6335.
doi: 10.13801/j.cnki.fhclxb.20230214.001
Abstract:
In order to enhance the seismic capacity of concrete flexural members, a graded reinforcement scheme with the glass fiber reinforced plastic (GFRP) bars and the steel bars was developed to make a graded distribution of bearing capacity that matches the external force distribution, and then multiple-plastic regions were formed. Five concrete flexural members with different graded reinforcement parameters were designed, and the comparison parameters included the height of the grades, the type of bars, the reinforcement ratios and the construction methods. Through the pushover experiment, the formation and mechanical effects of multi-plastic regions were studied, and the formation mechanism of multi-plastic regions was analyzed in details. The results show that the reasonable graded reinforcement scheme can form multi-plastic regions in the concrete flexural member. The number and development degree of plastic regions significantly affect the seismic behaviours of members. The formation condition of the multi-plastic regions is that the external moment is between the sectional yield moment and ultimate moment in several grades. The development level of each plastic region can be effectively controlled by adjusting the length and reinforcement of the grades, and the failure position and failure mode of the member can be designed. A great increment provided by GFRP bars with line elasticity properties on the bending bearing capacity after yielding is a key factor for the formation and regulation of multi-plastic regions.
In order to enhance the seismic capacity of concrete flexural members, a graded reinforcement scheme with the glass fiber reinforced plastic (GFRP) bars and the steel bars was developed to make a graded distribution of bearing capacity that matches the external force distribution, and then multiple-plastic regions were formed. Five concrete flexural members with different graded reinforcement parameters were designed, and the comparison parameters included the height of the grades, the type of bars, the reinforcement ratios and the construction methods. Through the pushover experiment, the formation and mechanical effects of multi-plastic regions were studied, and the formation mechanism of multi-plastic regions was analyzed in details. The results show that the reasonable graded reinforcement scheme can form multi-plastic regions in the concrete flexural member. The number and development degree of plastic regions significantly affect the seismic behaviours of members. The formation condition of the multi-plastic regions is that the external moment is between the sectional yield moment and ultimate moment in several grades. The development level of each plastic region can be effectively controlled by adjusting the length and reinforcement of the grades, and the failure position and failure mode of the member can be designed. A great increment provided by GFRP bars with line elasticity properties on the bending bearing capacity after yielding is a key factor for the formation and regulation of multi-plastic regions.
2023, 40(11): 6336-6350.
doi: 10.13801/j.cnki.fhclxb.20230215.003
Abstract:
In order to solve the problem that graphene (G) is uniformly dispersed in cement slurry and its dosage is too high when it is functionalized into cement-based materials, a graphene (G-SD) with both high conductivity and water solubility was selected as a conductive filler. The effect of sodium lignosulfonate (MN) on the dispersion ability of G-SD in saturated calcium hydroxide solution (CH) used for simulated cement pore solution in the presence of polycarboxylate superplasticizer (PCE) and the effects of G-SD on the resistivity, electrothermal properties, snow melting and deciding, and thermoelectric properties of cement paste were investigated. The absorbance test shows that when the mass ratio of MN to G-SD is 3∶1, the dispersion of G-SD reaches the best. The electrical performance test shows that percolation threshold of graphene cement-based materials is 0.4%. What's more, good electrothermal performance are shown under the threshold, the temperature of cement paste specimen can be increased by 320℃ for 20 min with 30 V voltage, and 4 cm thick ice layer can be basically melted within25 min, so it possesses good potential for deicing and snow-melting. The thermoelectric properties shows that Seebeck coefficient of cement paste specimen is 154.4 μV/K when the content of G-SD is 0.1% by the cement mass. The above studies show that G-SD can endow cement-based materials with excellent electrical, thermal and thermoelectric functional properties at very low dosage.
In order to solve the problem that graphene (G) is uniformly dispersed in cement slurry and its dosage is too high when it is functionalized into cement-based materials, a graphene (G-SD) with both high conductivity and water solubility was selected as a conductive filler. The effect of sodium lignosulfonate (MN) on the dispersion ability of G-SD in saturated calcium hydroxide solution (CH) used for simulated cement pore solution in the presence of polycarboxylate superplasticizer (PCE) and the effects of G-SD on the resistivity, electrothermal properties, snow melting and deciding, and thermoelectric properties of cement paste were investigated. The absorbance test shows that when the mass ratio of MN to G-SD is 3∶1, the dispersion of G-SD reaches the best. The electrical performance test shows that percolation threshold of graphene cement-based materials is 0.4%. What's more, good electrothermal performance are shown under the threshold, the temperature of cement paste specimen can be increased by 320℃ for 20 min with 30 V voltage, and 4 cm thick ice layer can be basically melted within25 min, so it possesses good potential for deicing and snow-melting. The thermoelectric properties shows that Seebeck coefficient of cement paste specimen is 154.4 μV/K when the content of G-SD is 0.1% by the cement mass. The above studies show that G-SD can endow cement-based materials with excellent electrical, thermal and thermoelectric functional properties at very low dosage.
2023, 40(11): 6351-6362.
doi: 10.13801/j.cnki.fhclxb.20230222.007
Abstract:
Four kinds of composite plates with different ply structures were fabricated, which are composed of thermosetting epoxy twill woven prepreg, diamond-shaped stainless steel wire mesh and aluminum alloy wire mesh. Further, low-velocity impact and compression after impact (CAI) experiments were conducted to study their damage behavior and post-impact residual compressive strength of the hybrid metal mesh structure under different energy levels. According to the double cantilever beam (DCB) tensile test and the end-notched flexure (ENF) test, the effects of metal mesh layers on the interlaminar fracture performance of carbon fiber composites were investigated. Ultrasonic scanning and two-dimensional virtual image correlation (2D-VIC) test system were employed to examine the damaged degree inside the specimen after impact and the deformation contour of the surface during the CAI test, then the strengthening mechanism were illuminated. The results show that the addition of metal mesh layers can improve the plasticity of the panel and effect area of incident energy, resulting in the improvement of absorbing impact energy, CAI strength and interlaminar shear performance. It is further found that in the ENF test of the hybrid panel, the interface damage includes not only the damage of matrix, but also the shear fracture of fiber.
Four kinds of composite plates with different ply structures were fabricated, which are composed of thermosetting epoxy twill woven prepreg, diamond-shaped stainless steel wire mesh and aluminum alloy wire mesh. Further, low-velocity impact and compression after impact (CAI) experiments were conducted to study their damage behavior and post-impact residual compressive strength of the hybrid metal mesh structure under different energy levels. According to the double cantilever beam (DCB) tensile test and the end-notched flexure (ENF) test, the effects of metal mesh layers on the interlaminar fracture performance of carbon fiber composites were investigated. Ultrasonic scanning and two-dimensional virtual image correlation (2D-VIC) test system were employed to examine the damaged degree inside the specimen after impact and the deformation contour of the surface during the CAI test, then the strengthening mechanism were illuminated. The results show that the addition of metal mesh layers can improve the plasticity of the panel and effect area of incident energy, resulting in the improvement of absorbing impact energy, CAI strength and interlaminar shear performance. It is further found that in the ENF test of the hybrid panel, the interface damage includes not only the damage of matrix, but also the shear fracture of fiber.
2023, 40(11): 6363-6373.
doi: 10.13801/j.cnki.fhclxb.20221208.002
Abstract:
Tension-tension fatigue tests at stress ratio Rs=0.1 were carried out on Austenitic stainless steel (316L)-Martensitic stainless steel (2Cr13) (316L-2Cr13) multilayer steel, all 316L multilayer steel and all 2Cr13 multilayer steel samples using up-and-down method and group method. The stress-life (S-N) curve was obtained and the fracture surface was analyzed. The results show that the S-N curve of multilayer steel has obvious horizontal section and definite fatigue limit due to the non-uniform microstructure in rolling state. The fatigue property of 316L-2Cr13 multilayer stainless steel composite plate is obviously better than that of all 316L or all 2Cr13 multilayer steel. When the stress ratio is 0.1, its fatigue strength can reach 286 MPa. The 316L-2Cr13 multlayer stainless steel composite plate combines the advantages of its constituent materials. 2Cr13 provides high strength to prevent rapid crack initiation of the sample, and 316L provides excellent plasticity to prevent crack propagation. The fatigue fracture surface of multilayer steel consists of fatigue source zone, crack propagation zone and final fracture zone, and the cracks nucleate at the stress concentration. In the crack propagation zone, a large number of fatigue striations exist in the 316L layer, and then dimples gradually form in the fatigue striations. At the same time, brittle transgranular fracture was observed in 2Cr13 layer, which was mainly composed of large cleavage surfaces in the later stage of crack growth. In the transient fracture zone of 316L-2Cr13 multilayer stainless steel composite plate, 2Cr13 layer presents a large number of cleavage surfaces, 316L is composed of a large number of dimples, and the layers are connected by shear dimples.
Tension-tension fatigue tests at stress ratio Rs=0.1 were carried out on Austenitic stainless steel (316L)-Martensitic stainless steel (2Cr13) (316L-2Cr13) multilayer steel, all 316L multilayer steel and all 2Cr13 multilayer steel samples using up-and-down method and group method. The stress-life (S-N) curve was obtained and the fracture surface was analyzed. The results show that the S-N curve of multilayer steel has obvious horizontal section and definite fatigue limit due to the non-uniform microstructure in rolling state. The fatigue property of 316L-2Cr13 multilayer stainless steel composite plate is obviously better than that of all 316L or all 2Cr13 multilayer steel. When the stress ratio is 0.1, its fatigue strength can reach 286 MPa. The 316L-2Cr13 multlayer stainless steel composite plate combines the advantages of its constituent materials. 2Cr13 provides high strength to prevent rapid crack initiation of the sample, and 316L provides excellent plasticity to prevent crack propagation. The fatigue fracture surface of multilayer steel consists of fatigue source zone, crack propagation zone and final fracture zone, and the cracks nucleate at the stress concentration. In the crack propagation zone, a large number of fatigue striations exist in the 316L layer, and then dimples gradually form in the fatigue striations. At the same time, brittle transgranular fracture was observed in 2Cr13 layer, which was mainly composed of large cleavage surfaces in the later stage of crack growth. In the transient fracture zone of 316L-2Cr13 multilayer stainless steel composite plate, 2Cr13 layer presents a large number of cleavage surfaces, 316L is composed of a large number of dimples, and the layers are connected by shear dimples.
2023, 40(11): 6374-6382.
doi: 10.13801/j.cnki.fhclxb.20230426.002
Abstract:
Coaxial electrospinning technology is based on the improvement of traditional electrospinning technology. The fiber material prepared by it not only has a high specific surface area, but also has a special core-shell structure, which can encapsulate active molecules, maintain their biological activity, and achieve the goal of sustained release. This article uses coaxial electrospinning technology to prepare gelatin (GEL)@poly(L-lactic acid) (PLLA) nanofiber membranes with core-shell structure. The morphology, structure, and properties of nanofiber membranes were characterized using scanning electron microscopy (SEM), laser confocal microscopy (LSCM), tensile testing, and contact angle testing. The influence of electrospinning process parameters on the morphology of nanofibers was explored, and the biocompatibility of nanofiber membranes was investigated. The results showed that the surface of the prepared GEL@PLLA core-shell nanofibers was smooth and had a clear core-shell structure. Increasing the flow velocity ratio between the core-shell layers increases the average diameter of the nanofibers from 231.41 nm to 279.49 nm. Increasing the spinning voltage gradually reduces the fiber diameter. By increasing the receiving distance, the fiber diameter decreases first and then increases. The contact angle of the GEL@PLLA fiber membrane is 126.7°, which exhibits hydrophobicity compared to pure GEL fiber membrane. The mechanical test results show that GEL@PLLA core-shell nanofibers have good flexibility and elasticity. The results of in vitro cell culture showed that bone marrow mesenchymal stem cells (BMSCs) can adhere and proliferate on the GEL@PLLA fiber membrane, indicate that the core-shell nanofiber membrane has good biocompatibility. This study can lay the foundation for the further application of fiber membranes in drug-controlled release systems and biomedical fields.
Coaxial electrospinning technology is based on the improvement of traditional electrospinning technology. The fiber material prepared by it not only has a high specific surface area, but also has a special core-shell structure, which can encapsulate active molecules, maintain their biological activity, and achieve the goal of sustained release. This article uses coaxial electrospinning technology to prepare gelatin (GEL)@poly(L-lactic acid) (PLLA) nanofiber membranes with core-shell structure. The morphology, structure, and properties of nanofiber membranes were characterized using scanning electron microscopy (SEM), laser confocal microscopy (LSCM), tensile testing, and contact angle testing. The influence of electrospinning process parameters on the morphology of nanofibers was explored, and the biocompatibility of nanofiber membranes was investigated. The results showed that the surface of the prepared GEL@PLLA core-shell nanofibers was smooth and had a clear core-shell structure. Increasing the flow velocity ratio between the core-shell layers increases the average diameter of the nanofibers from 231.41 nm to 279.49 nm. Increasing the spinning voltage gradually reduces the fiber diameter. By increasing the receiving distance, the fiber diameter decreases first and then increases. The contact angle of the GEL@PLLA fiber membrane is 126.7°, which exhibits hydrophobicity compared to pure GEL fiber membrane. The mechanical test results show that GEL@PLLA core-shell nanofibers have good flexibility and elasticity. The results of in vitro cell culture showed that bone marrow mesenchymal stem cells (BMSCs) can adhere and proliferate on the GEL@PLLA fiber membrane, indicate that the core-shell nanofiber membrane has good biocompatibility. This study can lay the foundation for the further application of fiber membranes in drug-controlled release systems and biomedical fields.
2023, 40(11): 6383-6394.
doi: 10.13801/j.cnki.fhclxb.20230222.011
Abstract:
Guangxi's large amount of waste fir sawdust is a valuable resource in the wrong place. In order to realize cyclic utilization of fir sawdust, biochar composites with magnetic recovery capability were prepared from waste fir sawdust, and the performance of activated peroxymonosulfate (PMS) to degrade levofloxacin (LEV) antibiotics was studied in this study. Magnetic nitrogen-doped fir sawdust biochar (MNC) with high PMS activation ability and excellent magnetic separation performance was synthesized by nitrogen doping and loading Fe3O4. Several characterizations confirm that compared with fir sawdust biochar (BC), MNC has higher graphitization, more defect active sites, significantly improved specific surface area, superparamagnetism and large magnetic saturation intensity, with a saturation magnetization value of 10.45 emu·g−1. In addition, the effects of various environmental factors on the degradation of LEV by MNC are simulated. The effects of PMS concentration, MNC dosage, initial pH of solution, inorganic anions and humic acid are mainly investigated. The results shows that compares with BC, magnetic biochar (MC) and nitrogen doped biochar (NC), the efficiency of degradation of LEV by MNC activated PMS is significantly improved. Under the conditions of MNC dosage of 1.0 g/L, PMS concentration of 0.3 mmol/L, initial pH of 7, and LEV concentration of 10 mg/L, the removal rate of LEV reachs 84% in 30 minutes, and the removal rates of bisphenol A (BPA), rhodamine B (RhB), and tetracycline (TC) are 94%, 98% and 87%, respectively. Cl−, NO3− and humic acid have no obvious effect on the degradation of LEV by MNC activated PMS. The quenching experiments show the generation of O2−• and 1O2 through free radical and non-free radical pathways dominate the degradation of LEV in MNC/PMS system. In addition, after 4 cycles of MNC, the efficiency of activating PMS to remove LEV can still reach about 75%. This study provides a new strategy and reference for the efficient and green resource utilization of waste fir sawdust.
Guangxi's large amount of waste fir sawdust is a valuable resource in the wrong place. In order to realize cyclic utilization of fir sawdust, biochar composites with magnetic recovery capability were prepared from waste fir sawdust, and the performance of activated peroxymonosulfate (PMS) to degrade levofloxacin (LEV) antibiotics was studied in this study. Magnetic nitrogen-doped fir sawdust biochar (MNC) with high PMS activation ability and excellent magnetic separation performance was synthesized by nitrogen doping and loading Fe3O4. Several characterizations confirm that compared with fir sawdust biochar (BC), MNC has higher graphitization, more defect active sites, significantly improved specific surface area, superparamagnetism and large magnetic saturation intensity, with a saturation magnetization value of 10.45 emu·g−1. In addition, the effects of various environmental factors on the degradation of LEV by MNC are simulated. The effects of PMS concentration, MNC dosage, initial pH of solution, inorganic anions and humic acid are mainly investigated. The results shows that compares with BC, magnetic biochar (MC) and nitrogen doped biochar (NC), the efficiency of degradation of LEV by MNC activated PMS is significantly improved. Under the conditions of MNC dosage of 1.0 g/L, PMS concentration of 0.3 mmol/L, initial pH of 7, and LEV concentration of 10 mg/L, the removal rate of LEV reachs 84% in 30 minutes, and the removal rates of bisphenol A (BPA), rhodamine B (RhB), and tetracycline (TC) are 94%, 98% and 87%, respectively. Cl−, NO3− and humic acid have no obvious effect on the degradation of LEV by MNC activated PMS. The quenching experiments show the generation of O2−• and 1O2 through free radical and non-free radical pathways dominate the degradation of LEV in MNC/PMS system. In addition, after 4 cycles of MNC, the efficiency of activating PMS to remove LEV can still reach about 75%. This study provides a new strategy and reference for the efficient and green resource utilization of waste fir sawdust.
2023, 40(11): 6395-6406.
doi: 10.13801/j.cnki.fhclxb.20230131.001
Abstract:
Biochar is a product of pyrolysis of biomass under anoxic conditions; however, common biochar has a small surface area, underdeveloped pore structure, few surface active groups, and poor adsorption effect. In this work, biochar was prepared from sorghum (GC) and grapefruit peel (YC) by surface treatment using four substances to obtain biochar, where the prepared sorghum/KOH (GC-KH) and grapefruit peel/KOH (YC-K) powders had obvious surface porosity, confirming the feasibility of the process. With a specific surface area of 2096.05 m2/g and an average pore size of 4.12 nm, GC-KH is rich in oxygen-containing functional groups on its surface, providing a good structural space and active sites for adsorption.The effect of different factors on phosphate adsorption was explored by batch experiments to assess the ionic strength. Results of isotherms showed that the adsorption of phosphate by GC-KH occurred on the surface of the monomolecular layer, and the maximum adsorption capacity of phosphate by GC-KH was 74.73 mg/g at pH=7. It has significant advantages such as rapid response, which provides an innovative pathway for the efficient removal of phosphate from wastewater.
Biochar is a product of pyrolysis of biomass under anoxic conditions; however, common biochar has a small surface area, underdeveloped pore structure, few surface active groups, and poor adsorption effect. In this work, biochar was prepared from sorghum (GC) and grapefruit peel (YC) by surface treatment using four substances to obtain biochar, where the prepared sorghum/KOH (GC-KH) and grapefruit peel/KOH (YC-K) powders had obvious surface porosity, confirming the feasibility of the process. With a specific surface area of 2096.05 m2/g and an average pore size of 4.12 nm, GC-KH is rich in oxygen-containing functional groups on its surface, providing a good structural space and active sites for adsorption.The effect of different factors on phosphate adsorption was explored by batch experiments to assess the ionic strength. Results of isotherms showed that the adsorption of phosphate by GC-KH occurred on the surface of the monomolecular layer, and the maximum adsorption capacity of phosphate by GC-KH was 74.73 mg/g at pH=7. It has significant advantages such as rapid response, which provides an innovative pathway for the efficient removal of phosphate from wastewater.
2023, 40(11): 6407-6415.
doi: 10.13801/j.cnki.fhclxb.20230109.003
Abstract:
With the rapid development of highly-integrated and highly-powered 5G communication and wearable electronic devices, the electromagnetic interference and electromagnetic pollution problems caused by electromagnetic waves are becoming increasingly serious. It is urgent to develop lightweight, mechanically strong and environmentally friendly electromagnetic shielding composites. Herein, the lightweight and mechanically strong MXene/bacterial cellulose (BC) composite aerogels with directional porous structures were prepared via the liquid nitrogen directional freezing followed by freeze drying method using biomass BC as matrix and conductive Ti3C2Tx MXene as functional fillers. The effects of Ti3C2Tx MXene mass fraction on the microstructures, conductive and mechanical properties, as well as EMI shielding properties of the composite aerogels were investigated in detail. The results show that the composite aerogels with a Ti3C2Tx MXene mass fraction of 40wt% exhibit a low mass density of 18.3 mg/cm3, as well as the highest electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) of 459.3 S/cm and 72 dB (at a thickness of 4 mm) in X band with an absorption dominated EMI shielding mechanism. Owing to the abundant hydrogen bonding interactions, the composite aerogels exhibit a high compression strength of 38.3 kPa, which is 116.1% higher than that of pure BC aerogels.
With the rapid development of highly-integrated and highly-powered 5G communication and wearable electronic devices, the electromagnetic interference and electromagnetic pollution problems caused by electromagnetic waves are becoming increasingly serious. It is urgent to develop lightweight, mechanically strong and environmentally friendly electromagnetic shielding composites. Herein, the lightweight and mechanically strong MXene/bacterial cellulose (BC) composite aerogels with directional porous structures were prepared via the liquid nitrogen directional freezing followed by freeze drying method using biomass BC as matrix and conductive Ti3C2Tx MXene as functional fillers. The effects of Ti3C2Tx MXene mass fraction on the microstructures, conductive and mechanical properties, as well as EMI shielding properties of the composite aerogels were investigated in detail. The results show that the composite aerogels with a Ti3C2Tx MXene mass fraction of 40wt% exhibit a low mass density of 18.3 mg/cm3, as well as the highest electrical conductivity and electromagnetic interference shielding effectiveness (EMI SE) of 459.3 S/cm and 72 dB (at a thickness of 4 mm) in X band with an absorption dominated EMI shielding mechanism. Owing to the abundant hydrogen bonding interactions, the composite aerogels exhibit a high compression strength of 38.3 kPa, which is 116.1% higher than that of pure BC aerogels.
2023, 40(11): 6416-6429.
doi: 10.13801/j.cnki.fhclxb.20230706.001
Abstract:
The ceramization process of polyborosilazane (PSNB), tris(methylamino)borane (PBN) and mixed precursors were studied respectively, and the influence of heat treatment temperature on the microstructure and properties of polymer derived ceramics was mastered. After pyrolysis under NH3, the B—Si—O—N multielement network was formed in PDC-SiBN, which had good crystallization resistance. After heat treatment at less than 1500℃, the moisture resistance of ceramics was improved, the dielectric constant was between 3.0 and 3.6, and the loss was about 0.003. After pyrolysis under NH3, the B—N—O structure was formed in PDC-BN, which gradually decomposed into BN with the increase of temperature. The precursor can be mixed in a certain proportion to control the elements of polymer derived ceramics. Due to the existence of heterogeneous interfaces in the mixed precursor derived ceramics, the multiple networks were reduced. The thermal stability and dielectric properties of mixed polymer derived ceramics are between those of single polymer derived ceramics, which have certain performance designability.
The ceramization process of polyborosilazane (PSNB), tris(methylamino)borane (PBN) and mixed precursors were studied respectively, and the influence of heat treatment temperature on the microstructure and properties of polymer derived ceramics was mastered. After pyrolysis under NH3, the B—Si—O—N multielement network was formed in PDC-SiBN, which had good crystallization resistance. After heat treatment at less than 1500℃, the moisture resistance of ceramics was improved, the dielectric constant was between 3.0 and 3.6, and the loss was about 0.003. After pyrolysis under NH3, the B—N—O structure was formed in PDC-BN, which gradually decomposed into BN with the increase of temperature. The precursor can be mixed in a certain proportion to control the elements of polymer derived ceramics. Due to the existence of heterogeneous interfaces in the mixed precursor derived ceramics, the multiple networks were reduced. The thermal stability and dielectric properties of mixed polymer derived ceramics are between those of single polymer derived ceramics, which have certain performance designability.
2023, 40(11): 6430-6438.
doi: 10.13801/j.cnki.fhclxb.20230112.001
Abstract:
In-situ TiB2/Al composite is a new type of aluminum matrix composite, which has the advantages of high specific strength and specific stiffness, good performances on wear resistance, electrical conductivity and thermal conductivity, a variety of matrix alloy candidates, low raw material cost, simple and diversified manufacturing and heat treatment processes. The existing research on the fatigue of in-situ TiB2/Al composites mainly focuses on the strengthening mechanism in micro-scale and the general understanding of its fatigue performance is not sufficient. It is also lack of fatigue test data of in-situ TiB2/Al composite for the engineering use. High cycle fatigue properties of the in-situ TiB2 particle reinforced 7050 aluminum alloy composite (in-situ TiB2/7050-Al) with volume fraction of 3.67vol% was experimentally investigated with comparison to 7050-Al, the matrix alloy of the composite. The results reveal that the fatigue strength of the in-situ TiB2/7050-Al is apparently higher than that of 7050-Al. The fatigue limits of in-situ TiB2/7050-Al are improved by 24.59% and 13.56% for stress ratios 0.1 and 0.5 separately, resulting from the increase of fatigue resistance induced by the tiny TiB2 particles. The results at different stress concentration levels show that the notch sensitivity of in-situ TiB2/7050-Al is higher than that of 7050-Al, which may attribute to TiB2 particles impeding the plastic deformation of the aluminum alloy matrix in the composite. Despite the higher notch sensitivity, the fatigue resistance of the notched composite is still higher than that of the 7050-Al. Therefore, in-situ TiB2/7050-Al is a promising material for lightweight structure application to replace traditional aluminum alloy in certain circumstances and achieve the joint improvement of static strength and fatigue performance.
In-situ TiB2/Al composite is a new type of aluminum matrix composite, which has the advantages of high specific strength and specific stiffness, good performances on wear resistance, electrical conductivity and thermal conductivity, a variety of matrix alloy candidates, low raw material cost, simple and diversified manufacturing and heat treatment processes. The existing research on the fatigue of in-situ TiB2/Al composites mainly focuses on the strengthening mechanism in micro-scale and the general understanding of its fatigue performance is not sufficient. It is also lack of fatigue test data of in-situ TiB2/Al composite for the engineering use. High cycle fatigue properties of the in-situ TiB2 particle reinforced 7050 aluminum alloy composite (in-situ TiB2/7050-Al) with volume fraction of 3.67vol% was experimentally investigated with comparison to 7050-Al, the matrix alloy of the composite. The results reveal that the fatigue strength of the in-situ TiB2/7050-Al is apparently higher than that of 7050-Al. The fatigue limits of in-situ TiB2/7050-Al are improved by 24.59% and 13.56% for stress ratios 0.1 and 0.5 separately, resulting from the increase of fatigue resistance induced by the tiny TiB2 particles. The results at different stress concentration levels show that the notch sensitivity of in-situ TiB2/7050-Al is higher than that of 7050-Al, which may attribute to TiB2 particles impeding the plastic deformation of the aluminum alloy matrix in the composite. Despite the higher notch sensitivity, the fatigue resistance of the notched composite is still higher than that of the 7050-Al. Therefore, in-situ TiB2/7050-Al is a promising material for lightweight structure application to replace traditional aluminum alloy in certain circumstances and achieve the joint improvement of static strength and fatigue performance.
2023, 40(11): 6439-6449.
doi: 10.13801/j.cnki.fhclxb.20221221.002
Abstract:
Ti/Al laminated composite plates have the advantages of high strength and corrosion resistance of titanium alloy, light mass and low price of aluminum alloy, and have a wide range of potential applications in aerospace, automobile manufacturing, underwater equipment and other fields. In order to investigate the connection behavior of Ti/Al laminated composite members, vacuum electron beam welding (EBW) was used to weld Ti/Al laminated composite members, and the microstructure, interface behavior and mechanical properties of the welded joints were studied. The results showed that: Compared with single-side welding, the mechanical properties of welded Ti/Al laminated composite plates can be effectively improved by double-sided Al welding followed by Ti welding. There are no obvious defects at the interface of welded Ti/Al joints, and there are obvious intermetallic compounds (IMCs) layers at the interface of welded Ti/Al joints. The formation sequence of the compounds is TiAl3, TiAl and TiAl2. TiAl2 is the product of a series of reactions in which TiAl is used as an intermediate. Under the condition that the electron beam of Al layer remains unchanged at 43 mA, with the increase of the electron beam of Ti layer, the tensile strength and elongation of the welded joint both increase first and then decrease. The maximum tensile strength and elongation can reach 304.6 MPa and 10.4%, which is 57% of the strength of the base metal. The fracture mechanism of welded joint is mainly brittle fracture at IMCs position.
Ti/Al laminated composite plates have the advantages of high strength and corrosion resistance of titanium alloy, light mass and low price of aluminum alloy, and have a wide range of potential applications in aerospace, automobile manufacturing, underwater equipment and other fields. In order to investigate the connection behavior of Ti/Al laminated composite members, vacuum electron beam welding (EBW) was used to weld Ti/Al laminated composite members, and the microstructure, interface behavior and mechanical properties of the welded joints were studied. The results showed that: Compared with single-side welding, the mechanical properties of welded Ti/Al laminated composite plates can be effectively improved by double-sided Al welding followed by Ti welding. There are no obvious defects at the interface of welded Ti/Al joints, and there are obvious intermetallic compounds (IMCs) layers at the interface of welded Ti/Al joints. The formation sequence of the compounds is TiAl3, TiAl and TiAl2. TiAl2 is the product of a series of reactions in which TiAl is used as an intermediate. Under the condition that the electron beam of Al layer remains unchanged at 43 mA, with the increase of the electron beam of Ti layer, the tensile strength and elongation of the welded joint both increase first and then decrease. The maximum tensile strength and elongation can reach 304.6 MPa and 10.4%, which is 57% of the strength of the base metal. The fracture mechanism of welded joint is mainly brittle fracture at IMCs position.
2023, 40(11): 6450-6461.
doi: 10.13801/j.cnki.fhclxb.20230213.002
Abstract:
This study aims to explore the crushing deformation characteristics and underlying energy dissipating mechanisms of carbon-fibre-reinforced plastic (CFRP)-aluminum-aluminum foam hybrid tubes under both axial (0°) and oblique (10°) loads. Quasi-static compressive tests for net CFRP (CF) tubes, net aluminum (Al) tubes, net aluminum foams (Af), Al-Af hybrid tubes and CFRP-Al-Af hybrid tubes were performed first. The energy absorptions of the Al-Af hybrid columns are always higher than that of the sum net parts under loading angles of 0° and 10°; the energy absorption of the CF-Al-Af hybrid columns reduces under a 0° loading angle while improves remarkably under a 10° loading angle compared with the sum of net parts. Next, numerical models for these hybrid tubes and the corresponding net parts were developed in LS-DYNA, and numerical results indicate that the energy absorption improvement of Al tubes promotes the load-carrying enhancement of Al-Af and CF-Al-Af hybrid tubes, because the Al tubes in hybrid happen more stable symmetric deformation compared with the “symmetric-diamond” hybrid deformation of the net Al tubes; whereas the energy absorption reductions of external CF tubes primarily decrease energy absorption of CF-Al-Af hybrid tubes, because the CFRP tubes in the hybrid occur axial splitting failure due to compressions of inner Al tubes. Finally, the analytical models on mean crushing forces for CF-Al-Af hybrid columns and corresponding net components under axial load were developed, and the results indicate that the developed analytical models can better predict the mean crushing forces of both hybrid columns and net parts.
This study aims to explore the crushing deformation characteristics and underlying energy dissipating mechanisms of carbon-fibre-reinforced plastic (CFRP)-aluminum-aluminum foam hybrid tubes under both axial (0°) and oblique (10°) loads. Quasi-static compressive tests for net CFRP (CF) tubes, net aluminum (Al) tubes, net aluminum foams (Af), Al-Af hybrid tubes and CFRP-Al-Af hybrid tubes were performed first. The energy absorptions of the Al-Af hybrid columns are always higher than that of the sum net parts under loading angles of 0° and 10°; the energy absorption of the CF-Al-Af hybrid columns reduces under a 0° loading angle while improves remarkably under a 10° loading angle compared with the sum of net parts. Next, numerical models for these hybrid tubes and the corresponding net parts were developed in LS-DYNA, and numerical results indicate that the energy absorption improvement of Al tubes promotes the load-carrying enhancement of Al-Af and CF-Al-Af hybrid tubes, because the Al tubes in hybrid happen more stable symmetric deformation compared with the “symmetric-diamond” hybrid deformation of the net Al tubes; whereas the energy absorption reductions of external CF tubes primarily decrease energy absorption of CF-Al-Af hybrid tubes, because the CFRP tubes in the hybrid occur axial splitting failure due to compressions of inner Al tubes. Finally, the analytical models on mean crushing forces for CF-Al-Af hybrid columns and corresponding net components under axial load were developed, and the results indicate that the developed analytical models can better predict the mean crushing forces of both hybrid columns and net parts.
2023, 40(11): 6462-6470.
doi: 10.13801/j.cnki.fhclxb.20230310.004
Abstract:
Composite materials have been widely used in architecture, medicine, aerospace and other fields because of their excellent properties, however, the damage monitoring of composite materials has always been one of the difficult problems concerned by experts and scholars at home and abroad. In this paper, shape memory alloy (SMA) was embedded in the composite, and the strain transfer effect of the interface layer was considered. Using the resistance sensing characteristics of SMA, a plastic damage monitoring model of SMA composite based on strain transfer was established, which realizes the real-time monitoring of plastic damage strain of composite materials. Based on the monitoring model, the effects of different material parameters on the average strain transfer rate between SMA and composite were discussed, and the damage monitoring behaviors of SMA under different initial states and temperature conditions were discussed. The results show that decreasing the thickness of the interface layer, increasing the shear modulus of the interface layer and increasing the embedded length of SMA all increase the average strain transfer rate of the interface. The change of SMA resistance and the plastic damage strain of the composite are piecewise linear. This study can provide a theoretical basis for further optimization design and application of SMA composite damage monitoring.
Composite materials have been widely used in architecture, medicine, aerospace and other fields because of their excellent properties, however, the damage monitoring of composite materials has always been one of the difficult problems concerned by experts and scholars at home and abroad. In this paper, shape memory alloy (SMA) was embedded in the composite, and the strain transfer effect of the interface layer was considered. Using the resistance sensing characteristics of SMA, a plastic damage monitoring model of SMA composite based on strain transfer was established, which realizes the real-time monitoring of plastic damage strain of composite materials. Based on the monitoring model, the effects of different material parameters on the average strain transfer rate between SMA and composite were discussed, and the damage monitoring behaviors of SMA under different initial states and temperature conditions were discussed. The results show that decreasing the thickness of the interface layer, increasing the shear modulus of the interface layer and increasing the embedded length of SMA all increase the average strain transfer rate of the interface. The change of SMA resistance and the plastic damage strain of the composite are piecewise linear. This study can provide a theoretical basis for further optimization design and application of SMA composite damage monitoring.
