2021 Vol. 38, No. 2
2021, 38(2): 287-297.
doi: 10.13801/j.cnki.fhclxb.20201016.001
Abstract:
Thermoelectric materials can realize direct conversion between heat energy and electric energy, which are safe and environmentally friendly energy materials. With the development of wearable electronic devices, flexible thermoelectric materials attract great interests in recent years. Although conventional inorganic thermoelectric materials have excellent thermoelectric properties, their developments as flexible materials are limited because of their poor brittleness. Poly(3, 4-ethyl-enedioxythiophene): polystyrenesulfonate (PEDOT: PSS) has great potential in the field of flexible thermoelectrics due to its high electrical conductivity, low thermal conductivity and good flexibility. Excellent thermoelectric and mechanical properties can be obtained when choosing appropriate in-organic fillers to mix with PEDOT: PSS. This review focuses on the recent progress of PEDOT: PSS-based flexible thermoelectric materials. We also summarize the effective approaches for improving the thermoelectric performance of PEDOT: PSS-based flexible thermoelectric materials. Finally, we highlight the approaches and challenges for achieving high-performance PEDOT: PSS-based flexible thermoelectric materials.
Thermoelectric materials can realize direct conversion between heat energy and electric energy, which are safe and environmentally friendly energy materials. With the development of wearable electronic devices, flexible thermoelectric materials attract great interests in recent years. Although conventional inorganic thermoelectric materials have excellent thermoelectric properties, their developments as flexible materials are limited because of their poor brittleness. Poly(3, 4-ethyl-enedioxythiophene): polystyrenesulfonate (PEDOT: PSS) has great potential in the field of flexible thermoelectrics due to its high electrical conductivity, low thermal conductivity and good flexibility. Excellent thermoelectric and mechanical properties can be obtained when choosing appropriate in-organic fillers to mix with PEDOT: PSS. This review focuses on the recent progress of PEDOT: PSS-based flexible thermoelectric materials. We also summarize the effective approaches for improving the thermoelectric performance of PEDOT: PSS-based flexible thermoelectric materials. Finally, we highlight the approaches and challenges for achieving high-performance PEDOT: PSS-based flexible thermoelectric materials.
2021, 38(2): 298-314.
doi: 10.13801/j.cnki.fhclxb.20200825.003
Abstract:
Metal-organic framework (MOF) is a new type of nano-material with porous and high specific surface area. Ionic liquids (IL) are characterized by good stability and functional design. Loading IL into the pores of MOF to achieve an effective combination of ionic liquids and MOF materials to develop new composite materials is conducive to giving full play to the advantages of the two materials. This article mainly introduces the latest research on the synthesis methods, structural properties and applications of IL/MOF composites, summarizes the current problems and opportunities in the research of IL/MOF composite materials, and prospects the development direction of IL/MOF composite materials.
Metal-organic framework (MOF) is a new type of nano-material with porous and high specific surface area. Ionic liquids (IL) are characterized by good stability and functional design. Loading IL into the pores of MOF to achieve an effective combination of ionic liquids and MOF materials to develop new composite materials is conducive to giving full play to the advantages of the two materials. This article mainly introduces the latest research on the synthesis methods, structural properties and applications of IL/MOF composites, summarizes the current problems and opportunities in the research of IL/MOF composite materials, and prospects the development direction of IL/MOF composite materials.
2021, 38(2): 315-338.
doi: 10.13801/j.cnki.fhclxb.20200909.002
Abstract:
As a kind of composite material designed by space continuous network configuration, the ceramic-metal co-continuous composite owns some special characteristics such as the resistance of friction and wear, high thermal shock resistance, low thermal expansion coefficient and so on, which make it has broad application prospects. Inside, the intrinsic properties of porous ceramic preforms as the ceramic reinforcement in the co-continuous composite have important impacts on the overall performance of the composite. In this review, the main progress in the current preparation methods and surface modification of porous ceramics are systematically analyzed, and both the preparation technology and the performance research of ceramic-metal co-continuous composite are summarized. Finally, we outline the four major challenges that may be encountered in the future development of ceramic-metal co-continuous composites.
As a kind of composite material designed by space continuous network configuration, the ceramic-metal co-continuous composite owns some special characteristics such as the resistance of friction and wear, high thermal shock resistance, low thermal expansion coefficient and so on, which make it has broad application prospects. Inside, the intrinsic properties of porous ceramic preforms as the ceramic reinforcement in the co-continuous composite have important impacts on the overall performance of the composite. In this review, the main progress in the current preparation methods and surface modification of porous ceramics are systematically analyzed, and both the preparation technology and the performance research of ceramic-metal co-continuous composite are summarized. Finally, we outline the four major challenges that may be encountered in the future development of ceramic-metal co-continuous composites.
2021, 38(2): 339-360.
doi: 10.13801/j.cnki.fhclxb.20200902.001
Abstract:
Graphene and its derivatives show potential applications in cementious engineering because they can remarkably improve the tensile strength, toughness, durability of the cement-based materials and give additional functionality to the composites due to their unique structure and excellent properties. In this paper, the structural characteristics and properties of graphene and graphene oxide (GO) are briefly described, and their preparation methods are also summarized; the dispersion of graphene and its derivatives in cement-based materials is reviewed; the research progress of mechanical properties, rheological properties, electrical properties, thermal properties and pressure-sensitive properties of graphene and its derivatives mixed cement-based materials are mainly reviewed. Finally the current problem and research trends are further analyzed.
Graphene and its derivatives show potential applications in cementious engineering because they can remarkably improve the tensile strength, toughness, durability of the cement-based materials and give additional functionality to the composites due to their unique structure and excellent properties. In this paper, the structural characteristics and properties of graphene and graphene oxide (GO) are briefly described, and their preparation methods are also summarized; the dispersion of graphene and its derivatives in cement-based materials is reviewed; the research progress of mechanical properties, rheological properties, electrical properties, thermal properties and pressure-sensitive properties of graphene and its derivatives mixed cement-based materials are mainly reviewed. Finally the current problem and research trends are further analyzed.
2021, 38(2): 361-379.
doi: 10.13801/j.cnki.fhclxb.20200715.001
Abstract:
Superhydrophobic, a kind of special wetting ability, primarily originated from the "Lotus effect". It is defined as a special surface with a static contact angle of water droplets greater than 150° or a sliding angle less than 10°. This review introduces the research on superhydrophobic theory and phenomena in nature and summarizes methods of superhydrophobic surface preparation and applications in recent years. The advantages and disadvantages of the templating method, the coating method and the etching method are compared, and improvement measures of these methods are proposed. Besides, one of the most important applications of superhydrophobic surface to the metal corrosion resistance is emphasized. At last, the fabrication of superhydrophobic surfaces with special abilities is introduced, such as self-healing superhydrophobic surfaces, wetting reversal superhydrophobic surfaces. In these fabrication methods, the templating method and the etching method have advantages of time saving and low costing, but are usually accompanied by poor stability and abrasion resistance. The etching method is easier to control surface parameters, but limited in usefulness.
Superhydrophobic, a kind of special wetting ability, primarily originated from the "Lotus effect". It is defined as a special surface with a static contact angle of water droplets greater than 150° or a sliding angle less than 10°. This review introduces the research on superhydrophobic theory and phenomena in nature and summarizes methods of superhydrophobic surface preparation and applications in recent years. The advantages and disadvantages of the templating method, the coating method and the etching method are compared, and improvement measures of these methods are proposed. Besides, one of the most important applications of superhydrophobic surface to the metal corrosion resistance is emphasized. At last, the fabrication of superhydrophobic surfaces with special abilities is introduced, such as self-healing superhydrophobic surfaces, wetting reversal superhydrophobic surfaces. In these fabrication methods, the templating method and the etching method have advantages of time saving and low costing, but are usually accompanied by poor stability and abrasion resistance. The etching method is easier to control surface parameters, but limited in usefulness.
2021, 38(2): 380-388.
doi: 10.13801/j.cnki.fhclxb.20201110.004
Abstract:
Silk fibroin materials have been made into flexible electronic devices with good biocompatibility, controllable biodegradability and diversity of regeneration morphology. In this paper, the effects of different dissolution methods on the preparation of silk regenerated materials are reviewed. At the same time, the preparation methods and properties of silk fibroin materials such as microspheres, membranes, fibers, gels, scaffolds, etc. are analyzed. Then, the development and application of silk fibroin based flexible electronic materials in recent years are summarized. Although studies have shown that various silk fibroin based advanced materials with excellent properties can be obtained for electronic applications, the industrialization road is still long. Considering the advantages of silk fibroin micro-nano structure and easy regeneration and processing, the flexible electronic products with high sensitivity, biocompatibility, durability and portability are expected to appear.
Silk fibroin materials have been made into flexible electronic devices with good biocompatibility, controllable biodegradability and diversity of regeneration morphology. In this paper, the effects of different dissolution methods on the preparation of silk regenerated materials are reviewed. At the same time, the preparation methods and properties of silk fibroin materials such as microspheres, membranes, fibers, gels, scaffolds, etc. are analyzed. Then, the development and application of silk fibroin based flexible electronic materials in recent years are summarized. Although studies have shown that various silk fibroin based advanced materials with excellent properties can be obtained for electronic applications, the industrialization road is still long. Considering the advantages of silk fibroin micro-nano structure and easy regeneration and processing, the flexible electronic products with high sensitivity, biocompatibility, durability and portability are expected to appear.
2021, 38(2): 389-397.
doi: 10.13801/j.cnki.fhclxb.20200601.001
Abstract:
Blocked solvent-free polyurethane (BSFPU) ultrafine synthetic leather base cloth was composed of polyamide 6-alkali soluble polyester (PA6-COPET) sea-island fiber nonwoven and blocked solvent-free polyurethane through impregnation, alkali decrement and finishing method. Microstructures changing during preparation were observed by scanning electron microscope, and then the effect of BSFPU leaching ratio on the mechanical property and hygienic performance of BSFPU ultrafine synthetic leather base cloth was studied. The results show that the sea island fibers are reduced to 37 bundles with a diameter of about 3 μm and the microstructure similar to natural leather is observed in BSFPU ultrafine synthetic leather base cloth. With the BSFPU leaching ratio increasing, the deweighting rate in the process of alkali decrement goes down from 31.59wt% to 28.22wt%; the elongation at break and tear strength of BSFPU ultrafine synthetic leather base cloth reduce continuously; the tensile strength almost remains the same result and the number begins to decline until the leaching ratio above 100wt%; the air permeability also decreases from 50 086 mL/(m2·s) to 24 757 mL/(m2·s) and the water vapor permeability reduces from 790.47 mg/(10 cm2·24 h) to 488.70 mg/(10 cm2·24 h). After testing, BSFPU ultrafine synthetic leather base cloth can meet the industry standards and its hygienic performance is significantly higher than commercially available solvent-based polyurethane ultrafine synthetic leather base cloth.
Blocked solvent-free polyurethane (BSFPU) ultrafine synthetic leather base cloth was composed of polyamide 6-alkali soluble polyester (PA6-COPET) sea-island fiber nonwoven and blocked solvent-free polyurethane through impregnation, alkali decrement and finishing method. Microstructures changing during preparation were observed by scanning electron microscope, and then the effect of BSFPU leaching ratio on the mechanical property and hygienic performance of BSFPU ultrafine synthetic leather base cloth was studied. The results show that the sea island fibers are reduced to 37 bundles with a diameter of about 3 μm and the microstructure similar to natural leather is observed in BSFPU ultrafine synthetic leather base cloth. With the BSFPU leaching ratio increasing, the deweighting rate in the process of alkali decrement goes down from 31.59wt% to 28.22wt%; the elongation at break and tear strength of BSFPU ultrafine synthetic leather base cloth reduce continuously; the tensile strength almost remains the same result and the number begins to decline until the leaching ratio above 100wt%; the air permeability also decreases from 50 086 mL/(m2·s) to 24 757 mL/(m2·s) and the water vapor permeability reduces from 790.47 mg/(10 cm2·24 h) to 488.70 mg/(10 cm2·24 h). After testing, BSFPU ultrafine synthetic leather base cloth can meet the industry standards and its hygienic performance is significantly higher than commercially available solvent-based polyurethane ultrafine synthetic leather base cloth.
2021, 38(2): 398-405.
doi: 10.13801/j.cnki.fhclxb.20200610.004
Abstract:
Rice husk biochar and poplar biochar were prepared from rice husk and poplar at 600 °C in this study. Rice husk, rice husk biochar, poplar and poplar biochar were used to reinforce high density polyethylene (HDPE) to prepare composites, and properties of the composites were tested and analyzed respectively. The results show that higher carbon content, higher specific surface area and more developed pore structure are obtained in rice husk biochar and poplar biochar than rice husk and poplar. The flexural strength, flexural modulus, tensile strength and tensile modulus of rice husk biochar/HDPE composites are 34.95 MPa, 1.76 GPa, 26.25 MPa, 1.83 GPa, higher than those of rice husk/HDPE composites. Similarly, the flexural strength, flexural modulus, tensile strength and tensile modulus of poplar biochar are 40.14 MPa, 2.43 GPa, 30.64 MPa, 2.17 GPa, higher than those of poplar/HDPE composites. Besides, the creep resistance and anti-stress relaxation ability of rice husk biochar/HDPE composites and poplar/HDPE composites are also stronger than rice husk/HDPE composites and poplar/HDPE composites. The results of this study suggest that the mechanical properties of biochar/HDPE composites are better than biomass/HDPE composites, which can provide new ideas for the high value utilization of agroforestry wastes.
Rice husk biochar and poplar biochar were prepared from rice husk and poplar at 600 °C in this study. Rice husk, rice husk biochar, poplar and poplar biochar were used to reinforce high density polyethylene (HDPE) to prepare composites, and properties of the composites were tested and analyzed respectively. The results show that higher carbon content, higher specific surface area and more developed pore structure are obtained in rice husk biochar and poplar biochar than rice husk and poplar. The flexural strength, flexural modulus, tensile strength and tensile modulus of rice husk biochar/HDPE composites are 34.95 MPa, 1.76 GPa, 26.25 MPa, 1.83 GPa, higher than those of rice husk/HDPE composites. Similarly, the flexural strength, flexural modulus, tensile strength and tensile modulus of poplar biochar are 40.14 MPa, 2.43 GPa, 30.64 MPa, 2.17 GPa, higher than those of poplar/HDPE composites. Besides, the creep resistance and anti-stress relaxation ability of rice husk biochar/HDPE composites and poplar/HDPE composites are also stronger than rice husk/HDPE composites and poplar/HDPE composites. The results of this study suggest that the mechanical properties of biochar/HDPE composites are better than biomass/HDPE composites, which can provide new ideas for the high value utilization of agroforestry wastes.
2021, 38(2): 406-413.
doi: 10.13801/j.cnki.fhclxb.20200610.002
Abstract:
To improve the processing flowability and mechanical property of carbon fiber reinforced polyamide (CFRPA) composites, polyamide amine (PAMAM) dendrimer was used as flow modifier when the CFRPA was prepared from melt compounding. DSC, electromechanical universal testing machine and SEM were employed to characterize the crystallization behavior of the modified polyamide 66 (PA66) and the mechanical properties, microstructure morphology of CFRPA, respectively. Results indicate that by the addition of PAMAM, the fluidity of PA66 can be significantly improved and the viscosity of CFRPA melt blends can be effectively reduced. When the addition of PAMAM is 1wt% of PA66 matrix, a maximum crystallinity of 12.75% of PA66 is achieved. The melt flow rate (MFR) is increased to 112 g/10 min, which is 814.47% higher than that of the unmodified PA66. Correspondingly, the equilibrium torques of the CFRPA with different CF contents during melt blending are reduced, and CF can be uniformly dispersed in the PA66 matrix. CFRPA has a maximum tensile strength as high as 118 MPa with CF content of 40wt%.
To improve the processing flowability and mechanical property of carbon fiber reinforced polyamide (CFRPA) composites, polyamide amine (PAMAM) dendrimer was used as flow modifier when the CFRPA was prepared from melt compounding. DSC, electromechanical universal testing machine and SEM were employed to characterize the crystallization behavior of the modified polyamide 66 (PA66) and the mechanical properties, microstructure morphology of CFRPA, respectively. Results indicate that by the addition of PAMAM, the fluidity of PA66 can be significantly improved and the viscosity of CFRPA melt blends can be effectively reduced. When the addition of PAMAM is 1wt% of PA66 matrix, a maximum crystallinity of 12.75% of PA66 is achieved. The melt flow rate (MFR) is increased to 112 g/10 min, which is 814.47% higher than that of the unmodified PA66. Correspondingly, the equilibrium torques of the CFRPA with different CF contents during melt blending are reduced, and CF can be uniformly dispersed in the PA66 matrix. CFRPA has a maximum tensile strength as high as 118 MPa with CF content of 40wt%.
2021, 38(2): 414-423.
doi: 10.13801/j.cnki.fhclxb.20200528.001
Abstract:
Under constant pressure injection condition, glass fiber (GF) reinforced anionic polyamide-6 (APA-6) composites with up to 48vol% fiber contents were successfully manufactured using resin injection molding machine suitable for the reaction system and thermoplastic resin transfer molding (T-RTM) experimental platform which was designed for the process, utilizing the anionic polymerization of caprolactam. The effects of feeding methods, injection pressure, mold temperature and fiber contents on the apparent mass, crystallinity, thermal deformation temperature and mechanical properties of the products were studied. The results show that product with no defect on the surface and excellent performance can be obtained when the injection pressure is 0.5-1.0 MPa under the vacuum pressure with a certain overflow flow. The bending strength and modulus of GF/APA-6 composites reach the highest, 682.7 MPa and 24.4 GPa, respectively when the mold temperature is 150℃. Then, the interlaminar shear strength (ILSS) of composite materials can reach up to 62.3 MPa at 180℃.
Under constant pressure injection condition, glass fiber (GF) reinforced anionic polyamide-6 (APA-6) composites with up to 48vol% fiber contents were successfully manufactured using resin injection molding machine suitable for the reaction system and thermoplastic resin transfer molding (T-RTM) experimental platform which was designed for the process, utilizing the anionic polymerization of caprolactam. The effects of feeding methods, injection pressure, mold temperature and fiber contents on the apparent mass, crystallinity, thermal deformation temperature and mechanical properties of the products were studied. The results show that product with no defect on the surface and excellent performance can be obtained when the injection pressure is 0.5-1.0 MPa under the vacuum pressure with a certain overflow flow. The bending strength and modulus of GF/APA-6 composites reach the highest, 682.7 MPa and 24.4 GPa, respectively when the mold temperature is 150℃. Then, the interlaminar shear strength (ILSS) of composite materials can reach up to 62.3 MPa at 180℃.
2021, 38(2): 424-438.
doi: 10.13801/j.cnki.fhclxb.20200507.002
Abstract:
Nano-Fe3O4 particles were deposited on the surface of tea waste (TW) by co-precipitation method to form tea waste@nano-Fe3O4 magnetic composited material, and then spherical tea waste@nano-Fe3O4/calcium algnate (TW@nano-Fe3O4/CA) magnetic beads were prepared by sol-gel approach. The magnetic composites were characterized by SEM, XPS, XRD, vibrating sample magnetometer (VSM) and universal testing machine. The adsorption properties and mechanism of methylene blue (MB) from aqueous solution onto the beads were studied. The results show that the TW@nano-Fe3O4/CA beads possess a good magnetic response, with the diamters ranges from 1.2 mm to 1.7 mm. The composited beads display a rough and folded surface morphology and porous inner structure. The diameters and magnetic response of the beads increase while the adsorption abilities of MB decrease with the increasing content of TW@nano-Fe3O4 in the beads. The adsorption kinetics followed is second order, and the adsorption isotherm data are well fitted to Langmuir model. The adsorption process of MB onto the beads is spontaneous, entropy decreased and exothermic process. The Langmuir maximum adsorption capacity of MB onto the beads with 80% mass fraction of TW@nano-Fe3O4 is found to be 272.5 mg·g−1 at 303 K, which is increased by 86.7% than TW. The adsorbent shows satisfactory regeneration and recycling utiliziation performance.
Nano-Fe3O4 particles were deposited on the surface of tea waste (TW) by co-precipitation method to form tea waste@nano-Fe3O4 magnetic composited material, and then spherical tea waste@nano-Fe3O4/calcium algnate (TW@nano-Fe3O4/CA) magnetic beads were prepared by sol-gel approach. The magnetic composites were characterized by SEM, XPS, XRD, vibrating sample magnetometer (VSM) and universal testing machine. The adsorption properties and mechanism of methylene blue (MB) from aqueous solution onto the beads were studied. The results show that the TW@nano-Fe3O4/CA beads possess a good magnetic response, with the diamters ranges from 1.2 mm to 1.7 mm. The composited beads display a rough and folded surface morphology and porous inner structure. The diameters and magnetic response of the beads increase while the adsorption abilities of MB decrease with the increasing content of TW@nano-Fe3O4 in the beads. The adsorption kinetics followed is second order, and the adsorption isotherm data are well fitted to Langmuir model. The adsorption process of MB onto the beads is spontaneous, entropy decreased and exothermic process. The Langmuir maximum adsorption capacity of MB onto the beads with 80% mass fraction of TW@nano-Fe3O4 is found to be 272.5 mg·g−1 at 303 K, which is increased by 86.7% than TW. The adsorbent shows satisfactory regeneration and recycling utiliziation performance.
2021, 38(2): 439-448.
doi: 10.13801/j.cnki.fhclxb.20200608.003
Abstract:
The axial compression behaviour of circular carbon fiber reinforced polymer (CFRP) confined reactive powder concrete (RPC) filled steel tube stub columns was investigated. The mechanical tests of 12 CFRP confined steel tube-RPC stub columns, 4 steel tube-RPC stub columns and 4 steel tube stub columns were performed with the number of the CFRP layers and the steel tube thickness as parameters. The load-displacement curves were used to analyze the effects of the CFRP layer number and the steel tube thickness on the ultimate load and deformation capacity of the specimens. Subsequently, the performance indicators such as improvement coefficient, CFRP strain efficiency and ductility coefficient were discussed. Finally, a model of CFRP confined steel tube-RPC stub columns was proposed by increasing the coefficient associated confinement ratio. The experimental results indicate that the bearing capacity and deformation capacity of the CFRP confined steel tube-RPC stub columns are significantly improved by CFRP. In contrast to the CFRP confined concrete filled steel tube (CFRP confined steel tube-C), the CFRP confined steel tube-RPC exhibites a decrease in CFRP strain efficiency, and its ductility is worse than the CFRP confined steel tube-C. Based on the bearing capacity of steel tube-RPC, a practical model for calculating the bearing capacity of CFRP confined steel tube-RPC stub columns is proposed.
The axial compression behaviour of circular carbon fiber reinforced polymer (CFRP) confined reactive powder concrete (RPC) filled steel tube stub columns was investigated. The mechanical tests of 12 CFRP confined steel tube-RPC stub columns, 4 steel tube-RPC stub columns and 4 steel tube stub columns were performed with the number of the CFRP layers and the steel tube thickness as parameters. The load-displacement curves were used to analyze the effects of the CFRP layer number and the steel tube thickness on the ultimate load and deformation capacity of the specimens. Subsequently, the performance indicators such as improvement coefficient, CFRP strain efficiency and ductility coefficient were discussed. Finally, a model of CFRP confined steel tube-RPC stub columns was proposed by increasing the coefficient associated confinement ratio. The experimental results indicate that the bearing capacity and deformation capacity of the CFRP confined steel tube-RPC stub columns are significantly improved by CFRP. In contrast to the CFRP confined concrete filled steel tube (CFRP confined steel tube-C), the CFRP confined steel tube-RPC exhibites a decrease in CFRP strain efficiency, and its ductility is worse than the CFRP confined steel tube-C. Based on the bearing capacity of steel tube-RPC, a practical model for calculating the bearing capacity of CFRP confined steel tube-RPC stub columns is proposed.
2021, 38(2): 449-460.
doi: 10.13801/j.cnki.fhclxb.20200608.002
Abstract:
The bond interface between steel and carbon fiber reinforced polymer (CFRP) plate is the weak part of steel structure strengthened by CFRP at high temperature. In order to explore the influence of temperature on the adhesive mechanics of steel to CFRP joints, some double lapped joint specimens were manufactured, and static tensile tests were conducted with three types of adhesives under four kinds of temperatures, which include 25℃, 55℃, 70℃ and 90℃. Thereafter, the failure modes, the load-displacement relationships, the strain distribution of CFRP plates and the bond-slip relationship of specimens were explored respectively. The results show that the failure modes of specimens are more related to the type of adhesive, when the temperature is lower than 55℃; but the failure modes of different adhesives are similar, and all the CFRP plates occur fracture when the temperature is higher than 70℃. The influence of temperature on the capacity of bond specimens is different, which depends on the type of epoxy resin adhesive. The capacities of HJY-4105 high toughness epoxy structural adhesive (HJY adhesive) specimens increase with the temperature increasing, and the capacities of LICA-100A/B epoxy structural adhesive (LICA adhesive) specimens are instability under different temperatures, and Sikadur-30 CN two-component epoxy structure reinforced carbon plate adhesive (SIKA30 adhesive) specimens have the highest capacity at 55℃. The shear strength of adhesive layer, the peak shear stress of interface and the shear stiffness decrease as the temperature increasing, but the ultimate tensile strength has no concern with the peak shear stress. Temperature has a significant effect on the bond-slip relationship, the ductility of the bond-slip constitutive of HJY adhesive increases with the increase of temperature, and the failure mode changes from brittle failure to ductile failure. The research shows that the reasonable high temperature resistant adhesive applied to steel structure reinforcement can adapt to the adverse effects of the natural high temperature environment.
The bond interface between steel and carbon fiber reinforced polymer (CFRP) plate is the weak part of steel structure strengthened by CFRP at high temperature. In order to explore the influence of temperature on the adhesive mechanics of steel to CFRP joints, some double lapped joint specimens were manufactured, and static tensile tests were conducted with three types of adhesives under four kinds of temperatures, which include 25℃, 55℃, 70℃ and 90℃. Thereafter, the failure modes, the load-displacement relationships, the strain distribution of CFRP plates and the bond-slip relationship of specimens were explored respectively. The results show that the failure modes of specimens are more related to the type of adhesive, when the temperature is lower than 55℃; but the failure modes of different adhesives are similar, and all the CFRP plates occur fracture when the temperature is higher than 70℃. The influence of temperature on the capacity of bond specimens is different, which depends on the type of epoxy resin adhesive. The capacities of HJY-4105 high toughness epoxy structural adhesive (HJY adhesive) specimens increase with the temperature increasing, and the capacities of LICA-100A/B epoxy structural adhesive (LICA adhesive) specimens are instability under different temperatures, and Sikadur-30 CN two-component epoxy structure reinforced carbon plate adhesive (SIKA30 adhesive) specimens have the highest capacity at 55℃. The shear strength of adhesive layer, the peak shear stress of interface and the shear stiffness decrease as the temperature increasing, but the ultimate tensile strength has no concern with the peak shear stress. Temperature has a significant effect on the bond-slip relationship, the ductility of the bond-slip constitutive of HJY adhesive increases with the increase of temperature, and the failure mode changes from brittle failure to ductile failure. The research shows that the reasonable high temperature resistant adhesive applied to steel structure reinforcement can adapt to the adverse effects of the natural high temperature environment.
2021, 38(2): 461-469.
doi: 10.13801/j.cnki.fhclxb.20200603.002
Abstract:
As a common natural phenomenon, ice accretion poses great security risks to aviation, power and road traffic. In this paper, an excellent composite of expanded graphite/polydimethylsiloxane (EG/PDMS) based ice detection and electrothermal de-icing function was designed by using the excellent conductivity of expanded graphite and the good flexibility and hydrophobicity of polydimethylsiloxane. Through experiments, the hydrophobicity, piezoresistive performance and electrothermal effect of the EG/PDMS composite material were analyzed. The sensor pressure sensitivity is up to 0.15 kPa−1, and the linear piezoresistive reaction can be generated in the range of 10~110 kPa; during the electric heating process when the input voltage is 30 V and the input current is 0.05 A, the maximum equilibrium temperature is 94.7℃, and the time to completely melt 10 g of ice is 166 s. The EG/PDMS composite material has great potential application value in the field of ice exploration/deicing. The composite material has great potential application value in the field of deicing.
As a common natural phenomenon, ice accretion poses great security risks to aviation, power and road traffic. In this paper, an excellent composite of expanded graphite/polydimethylsiloxane (EG/PDMS) based ice detection and electrothermal de-icing function was designed by using the excellent conductivity of expanded graphite and the good flexibility and hydrophobicity of polydimethylsiloxane. Through experiments, the hydrophobicity, piezoresistive performance and electrothermal effect of the EG/PDMS composite material were analyzed. The sensor pressure sensitivity is up to 0.15 kPa−1, and the linear piezoresistive reaction can be generated in the range of 10~110 kPa; during the electric heating process when the input voltage is 30 V and the input current is 0.05 A, the maximum equilibrium temperature is 94.7℃, and the time to completely melt 10 g of ice is 166 s. The EG/PDMS composite material has great potential application value in the field of ice exploration/deicing. The composite material has great potential application value in the field of deicing.
2021, 38(2): 470-478.
doi: 10.13801/j.cnki.fhclxb.20200610.001
Abstract:
The multiple H-bonds reinforced poly(acrylamide-co-2-vinyl-4,6-diamino-2-vinyl-1,3,5-triazine)/tannic acid (P(Am-co-VDT)/TA) hydrogels were prepared. Through testing and analysis of mechanical properties, micro-morphology and infrared spectrum, it's found that TA cross-linked the hydrogel through hydrogen bonding, making its structure more dense, and the hydrogel has high tensile strength (2.34 MPa) and elongation at break (410%). This is due to the formation of hydrogen-bond “soft” regions between the diaminotriazine (DAT) moieties on the polymer chains and the TA pyrogallol/catechol groups and a “hard” region of H-bonds forming by DAT moieties with itself. Such soft and hard dual-physically crosslinked networks dramatically enhance the mechanical properties of hydrogels in a synergistic manner. Due to the multiple hydrogen bonds, the hydrogel can rapidly response to shape memory within a few minutes. It can be quickly shaped and restored by changing the temperature, and the shape change can be maintained and repeated for many times. In addition, the hydrogels have capacity of physical adsorption of anti-inflammatory drug diclofenac sodium (DS) and other molecules with a specific spatially arranged chemical composition. This research will be of great significance in the fields of biomedicine, tissue engineering and medical materials.
The multiple H-bonds reinforced poly(acrylamide-co-2-vinyl-4,6-diamino-2-vinyl-1,3,5-triazine)/tannic acid (P(Am-co-VDT)/TA) hydrogels were prepared. Through testing and analysis of mechanical properties, micro-morphology and infrared spectrum, it's found that TA cross-linked the hydrogel through hydrogen bonding, making its structure more dense, and the hydrogel has high tensile strength (2.34 MPa) and elongation at break (410%). This is due to the formation of hydrogen-bond “soft” regions between the diaminotriazine (DAT) moieties on the polymer chains and the TA pyrogallol/catechol groups and a “hard” region of H-bonds forming by DAT moieties with itself. Such soft and hard dual-physically crosslinked networks dramatically enhance the mechanical properties of hydrogels in a synergistic manner. Due to the multiple hydrogen bonds, the hydrogel can rapidly response to shape memory within a few minutes. It can be quickly shaped and restored by changing the temperature, and the shape change can be maintained and repeated for many times. In addition, the hydrogels have capacity of physical adsorption of anti-inflammatory drug diclofenac sodium (DS) and other molecules with a specific spatially arranged chemical composition. This research will be of great significance in the fields of biomedicine, tissue engineering and medical materials.
2021, 38(2): 479-486.
doi: 10.13801/j.cnki.fhclxb.20200522.001
Abstract:
Cross-linkable phosphorylcholine polymer (Poly(MPC-co-LMA-co-TSMA), PMLT) was prepared by free radical polymerization. Coating the copolymer solution on the surface of polymethylpentene hollow fiber membrane (PMPHFM) can form a stable polymer coating after the cross-linking treatment and obtain a modified composite material PMLT/PMPHFM. The swelling test shows that the PMLT copolymer has good hydrophilic properties, and the swelling degree increases with the increase of MPC content and temperature. ATR-FTIR and XPS analysis show that the polymer coating containing phosphorylcholine groups exist on the surface of PMLT/PMPHFM. SEM and fluorescence test results show that the surface of PMLT/PMPHFM is coated with a uniform polymer coating, and the coating could resist the dissolution of ethanol and SDS aqueous solution. Platelet adhesion and whole blood contact tests show that the coating could reduce platelet adhesion on the surface of PMPHFM, reduce the risk of blood clotting compared to bare PMPHFM. The results show that the PMLT copolymer has good hydrophilic property, and can be uniformly coated on the surface of PMPHFM to obtain a composite material PMLT/PMPHFM with good blood compatibility.
Cross-linkable phosphorylcholine polymer (Poly(MPC-co-LMA-co-TSMA), PMLT) was prepared by free radical polymerization. Coating the copolymer solution on the surface of polymethylpentene hollow fiber membrane (PMPHFM) can form a stable polymer coating after the cross-linking treatment and obtain a modified composite material PMLT/PMPHFM. The swelling test shows that the PMLT copolymer has good hydrophilic properties, and the swelling degree increases with the increase of MPC content and temperature. ATR-FTIR and XPS analysis show that the polymer coating containing phosphorylcholine groups exist on the surface of PMLT/PMPHFM. SEM and fluorescence test results show that the surface of PMLT/PMPHFM is coated with a uniform polymer coating, and the coating could resist the dissolution of ethanol and SDS aqueous solution. Platelet adhesion and whole blood contact tests show that the coating could reduce platelet adhesion on the surface of PMPHFM, reduce the risk of blood clotting compared to bare PMPHFM. The results show that the PMLT copolymer has good hydrophilic property, and can be uniformly coated on the surface of PMPHFM to obtain a composite material PMLT/PMPHFM with good blood compatibility.
2021, 38(2): 487-495.
doi: 10.13801/j.cnki.fhclxb.20201215.009
Abstract:
Degradable material is an important part of biomaterials, its degradation performance in vivo has great influence on the final success after implantation. Thus, the method of evaluating the degradation of the materials in vivo is crucial to the evaluation of material performance. The traditional method to estimate the degradation in vivo needs to take out different batches of degradation samples at each sampling point, which prevents the continuous measurement of the degradation process and it needs a large number of samples. In vivo imaging system (IVIS) has the characteristics of non-invasive and strong operability, which provides a way to solve the problems above. In this study, we established a method to detect the degradation performance of degradable materials with IVIS. The research method was that the near-infrared fluorescent dye was labeled on the degradable materials by chemical reaction, and then using the change of fluorescence intensity to reflect the degradation degree of the materials. The in vivo degradation experimental results show that the fluorescent labeling materials prepared by this method have high fluorescence stability, and the fitting effect of fluorescence intensity and mass loss in the process of material degradation is good (R2 = 0.9994). In conclusion, this method solves the problem of large amount of samples in the traditional method of measuring material degradation, and improves the continuity of the experimental process.
Degradable material is an important part of biomaterials, its degradation performance in vivo has great influence on the final success after implantation. Thus, the method of evaluating the degradation of the materials in vivo is crucial to the evaluation of material performance. The traditional method to estimate the degradation in vivo needs to take out different batches of degradation samples at each sampling point, which prevents the continuous measurement of the degradation process and it needs a large number of samples. In vivo imaging system (IVIS) has the characteristics of non-invasive and strong operability, which provides a way to solve the problems above. In this study, we established a method to detect the degradation performance of degradable materials with IVIS. The research method was that the near-infrared fluorescent dye was labeled on the degradable materials by chemical reaction, and then using the change of fluorescence intensity to reflect the degradation degree of the materials. The in vivo degradation experimental results show that the fluorescent labeling materials prepared by this method have high fluorescence stability, and the fitting effect of fluorescence intensity and mass loss in the process of material degradation is good (R2 = 0.9994). In conclusion, this method solves the problem of large amount of samples in the traditional method of measuring material degradation, and improves the continuity of the experimental process.
2021, 38(2): 496-505.
doi: 10.13801/j.cnki.fhclxb.20200824.004
Abstract:
Co-precipitation method was applied for grafting magnetic Fe3O4 particles on carbon nanotubes. In order to improve the interlayer properties of carbon fiber reinforced polymer (CFRP), the magnetic carbon nanotubes (Fe3O4-MWCNTs) were aligned on the surface of carbon fiber by spraying process after exposure to magnetic field to form ‘carbon fiber-aligned carbon nanotubes-resin’ interface, and were fixed by spraying the resin. Aligned Fe3O4-MWCNTs-reinforced CFRP with excellent interlaminar properties was prepared by vacuum assisted resin infusion (VARI) molding. The test results show spraying resin plays an important role in consolidating and improving aligned spraying process. Compared with non-magnetic spraying process, when the mass fraction of Fe3O4-MWCNTs is 0.3wt%, the mode I interlaminar fracture toughness (GIC) increases by up to 37.7%. The main toughening mechanisms, which are pull-out and rupture of Fe3O4-MWCNTs aggregates, plastic deformation and plastic void growth of resin, are revealed by the fracture surface morphology. The research provides a new idea and method for interface modification of CFRP by adding Fe3O4-MWCNTs with controlled aligned behavior.
Co-precipitation method was applied for grafting magnetic Fe3O4 particles on carbon nanotubes. In order to improve the interlayer properties of carbon fiber reinforced polymer (CFRP), the magnetic carbon nanotubes (Fe3O4-MWCNTs) were aligned on the surface of carbon fiber by spraying process after exposure to magnetic field to form ‘carbon fiber-aligned carbon nanotubes-resin’ interface, and were fixed by spraying the resin. Aligned Fe3O4-MWCNTs-reinforced CFRP with excellent interlaminar properties was prepared by vacuum assisted resin infusion (VARI) molding. The test results show spraying resin plays an important role in consolidating and improving aligned spraying process. Compared with non-magnetic spraying process, when the mass fraction of Fe3O4-MWCNTs is 0.3wt%, the mode I interlaminar fracture toughness (GIC) increases by up to 37.7%. The main toughening mechanisms, which are pull-out and rupture of Fe3O4-MWCNTs aggregates, plastic deformation and plastic void growth of resin, are revealed by the fracture surface morphology. The research provides a new idea and method for interface modification of CFRP by adding Fe3O4-MWCNTs with controlled aligned behavior.
2021, 38(2): 506-516.
doi: 10.13801/j.cnki.fhclxb.20200622.002
Abstract:
The composite joints are increasingly used in foreign civil large-scale aircraft due to their light weight, high strength and designable structure. This work focused on the mechanical behaviour of a newly designed composite wound joints under tension and compression using finite element modelling method. Three typical structures, i.e., basic configuration, shuttle configuration, cone configuration, were compared to get the influence of different configurations on the mechanical behaviour of composite joints. Results show that all three structures have satisfying strength. The slope angles of shuttle and cone configurations were furtherly studied to increase the application of composite wound joints.
The composite joints are increasingly used in foreign civil large-scale aircraft due to their light weight, high strength and designable structure. This work focused on the mechanical behaviour of a newly designed composite wound joints under tension and compression using finite element modelling method. Three typical structures, i.e., basic configuration, shuttle configuration, cone configuration, were compared to get the influence of different configurations on the mechanical behaviour of composite joints. Results show that all three structures have satisfying strength. The slope angles of shuttle and cone configurations were furtherly studied to increase the application of composite wound joints.
Preparation of slippery surface based on femtosecond laser toward photo-induced droplet manipulation
2021, 38(2): 517-525.
doi: 10.13801/j.cnki.fhclxb.20200713.003
Abstract:
The droplet dynamic manipulation on photo-induced slippery lubricant-infused porous surface (SLIPS) has attracted tremendous attention because of its significant merits of contactless stimulation and excellent spatial and temporal control. However, the traditional fabrication methods by a combination of template-transfer and fluorination for a light-driven SLIPS are tedious and not environment-friendly. Accordingly, a kind of Fe3O4 nanoparticles(NPs)-doped nepenthes-inspired photothermal SLIPS was fabricated by femtosecond laser cross-scanning rapidly, which could readily steer diverse liquids towards arbitrary directions by utilizing droplet wettability gradient and internal Malangoni flow in the presence of unilateral near-infrared-irradiation-stimuli. Besides, the droplet manipulation performance was optimized by quantitatively analyzing the influence of Fe3O4-doped-content, lubricant rheological performance, diverse liquid species on sliding velocity and response time. The smart manipulator for controllable droplet directions and routes can be utilized to give an impetus to the extensive application of lab-on-a-chip, microfluidics and biomedical engineering and so on.
The droplet dynamic manipulation on photo-induced slippery lubricant-infused porous surface (SLIPS) has attracted tremendous attention because of its significant merits of contactless stimulation and excellent spatial and temporal control. However, the traditional fabrication methods by a combination of template-transfer and fluorination for a light-driven SLIPS are tedious and not environment-friendly. Accordingly, a kind of Fe3O4 nanoparticles(NPs)-doped nepenthes-inspired photothermal SLIPS was fabricated by femtosecond laser cross-scanning rapidly, which could readily steer diverse liquids towards arbitrary directions by utilizing droplet wettability gradient and internal Malangoni flow in the presence of unilateral near-infrared-irradiation-stimuli. Besides, the droplet manipulation performance was optimized by quantitatively analyzing the influence of Fe3O4-doped-content, lubricant rheological performance, diverse liquid species on sliding velocity and response time. The smart manipulator for controllable droplet directions and routes can be utilized to give an impetus to the extensive application of lab-on-a-chip, microfluidics and biomedical engineering and so on.
2021, 38(2): 526-535.
doi: 10.13801/j.cnki.fhclxb.20200603.004
Abstract:
In order to reduce the mechanical properties and the curing residual stress of the thick composite caused by the excessive temperature peak during the curing process, a multi-objective optimization model based on the multi-physics coupling characteristics was developed to reduce the maximum curing temperature peak and the curing time. Firstly, a three-dimensional model which incorporated three typical sub-models including thermo-chemical model, resin viscosity model and resin flow model was established to investigate the development of temperature and thickness of laminate during curing process. The results of numerical model were compared with experiment data in reference and good accordance was obtained. Then, a multi-objective optimization method was applied to optimize curing process parameters by using a radial basis function neural network model (RBF) as the surrogate model. It is shown that the curing temperature peak has a nonlinear relationship with the first and second dwell temperature, which is related to the nonlinear characteristics of the curing process. In order to reduce the temperature peak, it is necessary to increase the first dwell temperature and reduce the second dwell temperature. Meanwhile, the dwell time should also be adjusted to shorten the total curing time. Compared to standard cure profiles, the proposed optimization method can significantly reduce the curing time and temperature peak for thick composite laminates.
In order to reduce the mechanical properties and the curing residual stress of the thick composite caused by the excessive temperature peak during the curing process, a multi-objective optimization model based on the multi-physics coupling characteristics was developed to reduce the maximum curing temperature peak and the curing time. Firstly, a three-dimensional model which incorporated three typical sub-models including thermo-chemical model, resin viscosity model and resin flow model was established to investigate the development of temperature and thickness of laminate during curing process. The results of numerical model were compared with experiment data in reference and good accordance was obtained. Then, a multi-objective optimization method was applied to optimize curing process parameters by using a radial basis function neural network model (RBF) as the surrogate model. It is shown that the curing temperature peak has a nonlinear relationship with the first and second dwell temperature, which is related to the nonlinear characteristics of the curing process. In order to reduce the temperature peak, it is necessary to increase the first dwell temperature and reduce the second dwell temperature. Meanwhile, the dwell time should also be adjusted to shorten the total curing time. Compared to standard cure profiles, the proposed optimization method can significantly reduce the curing time and temperature peak for thick composite laminates.
2021, 38(2): 536-544.
doi: 10.13801/j.cnki.fhclxb.20200630.001
Abstract:
To overcome the excessive brittleness and lower thermal resistant of bismaleimide resins, the silicon dioxide with amino terminal groups (SiO2-NH2) was chosen as raw materials to prepare benzoxazine monomer containing SiO2 (SiO2-BOZ). The SiO2-BOZ was then used as the modified system to modify bismaleimide (BMI), aiming to obtain a kind of new SiO2-BOZ/BMI composites with better processability and heat-resistant properties, while the influence of addition of SiO2-BOZ on curing reaction kinetics of BMI was also studied. The results show that when the content of SiO2-BOZ reaches 15.0wt%, the apparent activation energy of SiO2-BOZ/BMI resin is reduced to a certain extent compared with that of pure BMI resin, and the bending strength of SiO2-BOZ/BMI reaches a maximum of 166.12 MPa, which is 32.3% higher than that of pure BMI, the SiO2-BOZ/BMI also possesses better heat resistance than that of BMI.
To overcome the excessive brittleness and lower thermal resistant of bismaleimide resins, the silicon dioxide with amino terminal groups (SiO2-NH2) was chosen as raw materials to prepare benzoxazine monomer containing SiO2 (SiO2-BOZ). The SiO2-BOZ was then used as the modified system to modify bismaleimide (BMI), aiming to obtain a kind of new SiO2-BOZ/BMI composites with better processability and heat-resistant properties, while the influence of addition of SiO2-BOZ on curing reaction kinetics of BMI was also studied. The results show that when the content of SiO2-BOZ reaches 15.0wt%, the apparent activation energy of SiO2-BOZ/BMI resin is reduced to a certain extent compared with that of pure BMI resin, and the bending strength of SiO2-BOZ/BMI reaches a maximum of 166.12 MPa, which is 32.3% higher than that of pure BMI, the SiO2-BOZ/BMI also possesses better heat resistance than that of BMI.
2021, 38(2): 545-556.
doi: 10.13801/j.cnki.fhclxb.20200609.001
Abstract:
To accurately predict the longitudinal tensile mechanical properties of 3D four-directional braided composites, parameter modeling for surface and interior unit-cells mesoscopic solid models was implemented and the deviation of yarn spatial traces and squeeze deformation of yarn cross-section were considered in the surface unit-cell model. Voxel mesh was used to discrete models on which appropriate boundary conditions were imposed and damage models for each constituent of composites were added into a user-defined material subroutine (UMAT) in finite element analysis software ABAQUS. By simulation analysis of surface-interior unit-cells models for 3D four-directional carbon fiber/epoxy braided composites with 30° and 45° interior braiding angles respectively, using the volume-weighted average method, longitudinal tensile modulus and strength for braided composites specimens with different thicknesses were predicted. The progressive damage process of composites was studied by counting the number of integration points with the same damage modes. Results show that the longitudinal tensile mechanical properties predicted based on surface-interior unit-cells models for 3D four-directional braided composites agree well with experimental results, and damage analysis results reflect reasonably progressive damage process of surface and interior unit-cells.
To accurately predict the longitudinal tensile mechanical properties of 3D four-directional braided composites, parameter modeling for surface and interior unit-cells mesoscopic solid models was implemented and the deviation of yarn spatial traces and squeeze deformation of yarn cross-section were considered in the surface unit-cell model. Voxel mesh was used to discrete models on which appropriate boundary conditions were imposed and damage models for each constituent of composites were added into a user-defined material subroutine (UMAT) in finite element analysis software ABAQUS. By simulation analysis of surface-interior unit-cells models for 3D four-directional carbon fiber/epoxy braided composites with 30° and 45° interior braiding angles respectively, using the volume-weighted average method, longitudinal tensile modulus and strength for braided composites specimens with different thicknesses were predicted. The progressive damage process of composites was studied by counting the number of integration points with the same damage modes. Results show that the longitudinal tensile mechanical properties predicted based on surface-interior unit-cells models for 3D four-directional braided composites agree well with experimental results, and damage analysis results reflect reasonably progressive damage process of surface and interior unit-cells.
2021, 38(2): 557-571.
doi: 10.13801/j.cnki.fhclxb.20200610.006
Abstract:
In this study, the WC and Co3O4 particles co-doped β-PbO2 composite coatings were synthesized on a Pb-0.3wt%Ag/α-PbO2 substrate using composite electrodeposition. The study of deposition behavior has found that WC particles are adsorbed on the substrate before Co3O4 particles, and co-deposition of WC particles and Co3O4 particles is an effective way to inhibit the agglomeration of Co3O4 particles when single co-deposited into β-PbO2 matrix. Electrode performance studies have found that co-deposition of WC or Co3O4 particles can both improve the electrocatalytic activity of oxygen evolution of the composite anode. In addition, WC particles can also help to improve the microhardness of the composite anode and the corrosion resistance in the Zn electrodeposition solution. The co-deposition of Co3O4 particles is not conducive to the growth of the β-PbO2 phase. The co-deposition of WC particles has little effect on the growth of the β-PbO2 phase. The simultaneous co-deposition of two particles helps to inhibit the growth of the α-PbO2 phase in the acid plating solution.
In this study, the WC and Co3O4 particles co-doped β-PbO2 composite coatings were synthesized on a Pb-0.3wt%Ag/α-PbO2 substrate using composite electrodeposition. The study of deposition behavior has found that WC particles are adsorbed on the substrate before Co3O4 particles, and co-deposition of WC particles and Co3O4 particles is an effective way to inhibit the agglomeration of Co3O4 particles when single co-deposited into β-PbO2 matrix. Electrode performance studies have found that co-deposition of WC or Co3O4 particles can both improve the electrocatalytic activity of oxygen evolution of the composite anode. In addition, WC particles can also help to improve the microhardness of the composite anode and the corrosion resistance in the Zn electrodeposition solution. The co-deposition of Co3O4 particles is not conducive to the growth of the β-PbO2 phase. The co-deposition of WC particles has little effect on the growth of the β-PbO2 phase. The simultaneous co-deposition of two particles helps to inhibit the growth of the α-PbO2 phase in the acid plating solution.
2021, 38(2): 572-582.
doi: 10.13801/j.cnki.fhclxb.20200703.001
Abstract:
The SiC particles (SiCP) reinforced Al composites of SiCP/ZL101 and SiCP/Al with 10vol% of SiCP were welded using Cu inter-layer under argon atmosphere at 550℃ by transient liquid phase diffusion bonding(TLP). The microstructure, shear strength, surface morphology of shear fracture and fracture path of the welded joints were analyzed. The results show that the Cu inter-layer is useful for the wetting of interface between the inter-layer metal and matrix by eutectic reaction of Al-Si-Cu (524℃) and Al-Cu (548℃) at eutectic temperature in the cast Al (ZL101) and pure Al (Al) matrix. Although some particles are gathered in the welded joints of cast Al matrix, the Cu content of the ternary eutectic reaction of Al-Si-Cu is 26.7wt%, which is lower than that of the binary eutectic reaction of Al-Cu (33wt%). Therefore it causes less CuAl2 phase without aggregation in the welded joints of SiCP/ZL101, which results in higher shear strength for the welded joints. While the intermetallic compound of CuAl2 phase remained in the welded joints has an important effect on the mechanical properties of the welded joints. The shear strength of the two composite joints are 85.4 MPa and 73 MPa, respectively.
The SiC particles (SiCP) reinforced Al composites of SiCP/ZL101 and SiCP/Al with 10vol% of SiCP were welded using Cu inter-layer under argon atmosphere at 550℃ by transient liquid phase diffusion bonding(TLP). The microstructure, shear strength, surface morphology of shear fracture and fracture path of the welded joints were analyzed. The results show that the Cu inter-layer is useful for the wetting of interface between the inter-layer metal and matrix by eutectic reaction of Al-Si-Cu (524℃) and Al-Cu (548℃) at eutectic temperature in the cast Al (ZL101) and pure Al (Al) matrix. Although some particles are gathered in the welded joints of cast Al matrix, the Cu content of the ternary eutectic reaction of Al-Si-Cu is 26.7wt%, which is lower than that of the binary eutectic reaction of Al-Cu (33wt%). Therefore it causes less CuAl2 phase without aggregation in the welded joints of SiCP/ZL101, which results in higher shear strength for the welded joints. While the intermetallic compound of CuAl2 phase remained in the welded joints has an important effect on the mechanical properties of the welded joints. The shear strength of the two composite joints are 85.4 MPa and 73 MPa, respectively.
2021, 38(2): 583-590.
doi: 10.13801/j.cnki.fhclxb.20200617.001
Abstract:
As the piezoelectric fiber composites have exhibited important applications in the areas of aerospace and aviation, it is necessary to investigate the effects of extreme environmental temperatures on their properties. In this study, the lead zirconate titanate (PAT) piezoelectric fiber composite was prepared, and the electrical impedance, free strain, actuation performance and mechanical properties of piezoelectric fiber composite were tested at different ambient temperatures. The results show that the phase angle difference of piezoelectric fiber composite changes at different ambient temperatures. Both the free strain and the actuation performance of piezoelectric fiber composite increase at first and then decrease as the ambient temperature increases. When the ambient temperature is 20℃, the longitudinal strain of the sample is 604.0×10−6, and the tip displacement generated by driving the aluminum plate is 0.789 mm. The maximum longitudinal free strains of the samples at −88℃ and 80℃ are reduced to 46.9% and 51.3% respectively, comparing with the value at 20℃, while the tip displacements are reduced to 79.6% and 83.7% respectively. When the ambient temperature increases from −88℃ to 80℃, the mechanical properties of piezoelectric fiber composites also increase.
As the piezoelectric fiber composites have exhibited important applications in the areas of aerospace and aviation, it is necessary to investigate the effects of extreme environmental temperatures on their properties. In this study, the lead zirconate titanate (PAT) piezoelectric fiber composite was prepared, and the electrical impedance, free strain, actuation performance and mechanical properties of piezoelectric fiber composite were tested at different ambient temperatures. The results show that the phase angle difference of piezoelectric fiber composite changes at different ambient temperatures. Both the free strain and the actuation performance of piezoelectric fiber composite increase at first and then decrease as the ambient temperature increases. When the ambient temperature is 20℃, the longitudinal strain of the sample is 604.0×10−6, and the tip displacement generated by driving the aluminum plate is 0.789 mm. The maximum longitudinal free strains of the samples at −88℃ and 80℃ are reduced to 46.9% and 51.3% respectively, comparing with the value at 20℃, while the tip displacements are reduced to 79.6% and 83.7% respectively. When the ambient temperature increases from −88℃ to 80℃, the mechanical properties of piezoelectric fiber composites also increase.
2021, 38(2): 591-600.
doi: 10.13801/j.cnki.fhclxb.20201011.001
Abstract:
The WS2/graphite phase nitrogen carbide(g-C3N4) heterojunction was established through the solvent evaporation and second calcinations the mixture of g-C3N4 nanosheets and WS2 nanosheets. The main structure of g-C3N4 and WS2 in the heterojunction is not destroyed in the calcinations process and the interface is connected by chemical bond, which enhances the stability of heterojunction. The photocatalysis results indicate that the H2 production rate reaches to 68.62 μmol/h while the content of WS2 is 3wt%, which are 2.53 times and 15.29 times as that of g-C3N4 nanosheets and WS2 nanosheets, respectively. Besides, the H2 production rate is not decreased distinctly after 5 times circulation experiments, which reveals that the WS2/g-C3N4 heterojunction has a good chemical stability. Photoelectric property indicates that the establish of heterojunction structure can not only enhance the transport rate of excited electrons, but also suppress the recombination rate of charge carriers. Thus, the H2 production rate is enhanced distinctly compared with that of pure g-C3N4 nanosheets and WS2 nanosheets.
The WS2/graphite phase nitrogen carbide(g-C3N4) heterojunction was established through the solvent evaporation and second calcinations the mixture of g-C3N4 nanosheets and WS2 nanosheets. The main structure of g-C3N4 and WS2 in the heterojunction is not destroyed in the calcinations process and the interface is connected by chemical bond, which enhances the stability of heterojunction. The photocatalysis results indicate that the H2 production rate reaches to 68.62 μmol/h while the content of WS2 is 3wt%, which are 2.53 times and 15.29 times as that of g-C3N4 nanosheets and WS2 nanosheets, respectively. Besides, the H2 production rate is not decreased distinctly after 5 times circulation experiments, which reveals that the WS2/g-C3N4 heterojunction has a good chemical stability. Photoelectric property indicates that the establish of heterojunction structure can not only enhance the transport rate of excited electrons, but also suppress the recombination rate of charge carriers. Thus, the H2 production rate is enhanced distinctly compared with that of pure g-C3N4 nanosheets and WS2 nanosheets.
2021, 38(2): 601-611.
doi: 10.13801/j.cnki.fhclxb.20200601.002
Abstract:
The interface between rubber macromolecules and inorganic nano-filler is an important factor to determine the properties of elastomer composites. The peak force quantitative nanomechanical mapping mode of atomic force microscopy (AFM-QNM) was attempted to quantify the interfacial nanomechanical properties and interfacial thickness of carbon nanotubes/Soluble styrene butadiene rubber (CNT/SSBR) composites, and reveal the effects of the specific surface area of the CNT on the interfacial nanomechanical properties and interfacial thickness of CNT/SSBR composites. The results show that with the increase of specific surface area of CNT, both the interfacial nanomechanical properties and interfacial thickness of CNT/SSBR composites gradually increase, which is due to the increase in the number of immobile rubber macromolecules chains acting on the CNT surface.
The interface between rubber macromolecules and inorganic nano-filler is an important factor to determine the properties of elastomer composites. The peak force quantitative nanomechanical mapping mode of atomic force microscopy (AFM-QNM) was attempted to quantify the interfacial nanomechanical properties and interfacial thickness of carbon nanotubes/Soluble styrene butadiene rubber (CNT/SSBR) composites, and reveal the effects of the specific surface area of the CNT on the interfacial nanomechanical properties and interfacial thickness of CNT/SSBR composites. The results show that with the increase of specific surface area of CNT, both the interfacial nanomechanical properties and interfacial thickness of CNT/SSBR composites gradually increase, which is due to the increase in the number of immobile rubber macromolecules chains acting on the CNT surface.
2021, 38(2): 612-621.
doi: 10.13801/j.cnki.fhclxb.20200610.005
Abstract:
In order to improve the toughness of cement-based materials, grapheme oxide (GO) was added into cement mortar. The effect of GO on the fracture properties of cement mortar was tested by three-point bending beam fracture test, and the fracture parameters were obtained through double K fracture model. The results show that GO improves the initial fracture toughness of cement mortar. When the GO content (mass ratio to cementitious material) is 0.01%-0.07%, the initial fracture toughness of GO reinforced cement mortar is increased by 13.4%, 25.4%, 24.6% and 16.7%, respectively, compared with the control group. However, the influence of GO on the unstable fracture toughness of cement mortar is limited. The fracture energies of GO reinforced cement mortars with different GO contents are increased by 10.7%-33.3%, compared with the control group. Combined with the microscopic test, it is found that the GO influences the hydration process of cement, optimizes pore structure and promotes the generation of high stiffness hydration products. It also improves the adhesion of hydration products, and further inhibits the generation and development of micro-cracks.
In order to improve the toughness of cement-based materials, grapheme oxide (GO) was added into cement mortar. The effect of GO on the fracture properties of cement mortar was tested by three-point bending beam fracture test, and the fracture parameters were obtained through double K fracture model. The results show that GO improves the initial fracture toughness of cement mortar. When the GO content (mass ratio to cementitious material) is 0.01%-0.07%, the initial fracture toughness of GO reinforced cement mortar is increased by 13.4%, 25.4%, 24.6% and 16.7%, respectively, compared with the control group. However, the influence of GO on the unstable fracture toughness of cement mortar is limited. The fracture energies of GO reinforced cement mortars with different GO contents are increased by 10.7%-33.3%, compared with the control group. Combined with the microscopic test, it is found that the GO influences the hydration process of cement, optimizes pore structure and promotes the generation of high stiffness hydration products. It also improves the adhesion of hydration products, and further inhibits the generation and development of micro-cracks.
2021, 38(2): 622-629.
doi: 10.13801/j.cnki.fhclxb.20200710.002
Abstract:
A novel water dispersible functional graphene (FG) was synthesized by the reaction of graphene oxide (GO) with an aryl diazonium salt (F) to solve the problem of uniformly dispersity of graphene nanosheets in the cement matrix. The maximum dispersibility of FG in water is 2.1 mg/mL. The successful surface modification of graphene using F was revealed by FTIR, Raman and XPS, respectively. Compared with the pure cement materials, the 28 days flexural strength and the compressive strength of the hydrophilic FG/cement composites are increased by 95.3% and 78.3%. The FG is uniformly dispersed in the cement matrix and the mechanical properties of the hydrophilic FG/cement composites are improved by the functional reaction between graphene and F.
A novel water dispersible functional graphene (FG) was synthesized by the reaction of graphene oxide (GO) with an aryl diazonium salt (F) to solve the problem of uniformly dispersity of graphene nanosheets in the cement matrix. The maximum dispersibility of FG in water is 2.1 mg/mL. The successful surface modification of graphene using F was revealed by FTIR, Raman and XPS, respectively. Compared with the pure cement materials, the 28 days flexural strength and the compressive strength of the hydrophilic FG/cement composites are increased by 95.3% and 78.3%. The FG is uniformly dispersed in the cement matrix and the mechanical properties of the hydrophilic FG/cement composites are improved by the functional reaction between graphene and F.
2021, 38(2): 630-640.
doi: 10.13801/j.cnki.fhclxb.20200608.001
Abstract:
Fracture tests were carried out on non-standard three-point bending self-compacting concrete(SCC) beams with different initial crack-depth ratios under different loading rates. The fracture parameters such as load-crack mouth opening displacement curve, peak load, fracture toughness, critical crack-depth ratio increment, elastic modulus and flexibility coefficient were obtained. Based on Pearson correlation test formula and loading rate effect model, the correlation between initial crack-depth ratio, loading rate and fracture parameters and the loading rate effect of SCC fracture parameters were quantitatively analyzed. The results show that the peak load, fracture toughness and elastic modulus all have loading rate effect in a certain extent. The flexibility coefficient is only related to the initial crack-depth ratio. The elastic modulus and fracture toughness are inherent properties of the material and are not affected by the initial crack-depth ratio. Meanwhile, the damage and fracture process, fracture boundary effect and crack propagation pattern of the SCC were analyzed based on acoustic emission(AE) technology. The results show that the AE parameters can well reflect the three-stage characteristics and boundary effect of concrete fracture. The propagation of crack is mainly tensile crack at first, and the proportion of shear crack increases with the fracture propagation process.
Fracture tests were carried out on non-standard three-point bending self-compacting concrete(SCC) beams with different initial crack-depth ratios under different loading rates. The fracture parameters such as load-crack mouth opening displacement curve, peak load, fracture toughness, critical crack-depth ratio increment, elastic modulus and flexibility coefficient were obtained. Based on Pearson correlation test formula and loading rate effect model, the correlation between initial crack-depth ratio, loading rate and fracture parameters and the loading rate effect of SCC fracture parameters were quantitatively analyzed. The results show that the peak load, fracture toughness and elastic modulus all have loading rate effect in a certain extent. The flexibility coefficient is only related to the initial crack-depth ratio. The elastic modulus and fracture toughness are inherent properties of the material and are not affected by the initial crack-depth ratio. Meanwhile, the damage and fracture process, fracture boundary effect and crack propagation pattern of the SCC were analyzed based on acoustic emission(AE) technology. The results show that the AE parameters can well reflect the three-stage characteristics and boundary effect of concrete fracture. The propagation of crack is mainly tensile crack at first, and the proportion of shear crack increases with the fracture propagation process.
