The carbon fiber reinforced composite is a new type of composite material with an excellent property in strength and elastic modulus,and has found extensive applications in aerospace,energy,automotive industry and so ...The carbon fiber reinforced composite is a new type of composite material with an excellent property in strength and elastic modulus,and has found extensive applications in aerospace,energy,automotive industry and so on.However,this composite has a strict requirement on processing techniques,for example,brittle damage or delamination often exists in conventional processing techniques.Abrasive water jet machining technology is a new type of green machining technique with distinct advantages such as high-energy and thermal distortion free.The use of abrasive water jet technique to process carbon fiber composite materials has become a popular trend since it can significantly improve the processing accuracy and surface quality of carbon fiber composite materials.However,there are too many parameters that affect the quality of an abrasive water jet machining.At present,few studies are carried out on the parameter optimization of such a machining process,which leads to the unstable quality of surface processing.In this paper,orthogonal design of experiment and regression analysis were employed to establish the empirical model between cutting surface roughness and machining process parameters.Then a verified model was used to optimize the machining process parameters for abrasive water jet cutting carbon fiber reinforced composites.展开更多
The fracture toughness of carbon fiber reinforced epoxy composite(CFRP)was investigated through mode I and mode II shaped fracture system in this paper.A novel polyimide with trifluoromethyl groups and grafted nanosil...The fracture toughness of carbon fiber reinforced epoxy composite(CFRP)was investigated through mode I and mode II shaped fracture system in this paper.A novel polyimide with trifluoromethyl groups and grafted nanosilica were used to modify epoxy resin.Effect of modified resin and unmodified resin on fracture toughness of CFRP was compared and discussed.Lay-up angles and thicknesses effects on fracture toughness of composites were also investigated.The fracture toughness of CFRP was obtained through double cantilever beam(DCB)and end notched flexure(ENF)tests.The results showed that the composites prepared by modified resin exhibited high fracture toughness compared with unmodified composites.The fracture toughness value of mode I increased from 1.83 kJ/m2 to 4.55 kJ/m2.The fracture toughness value of mode II increased from 2.30 kJ/m2 to 6.47 kJ/m2.展开更多
To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis(EDX) is used to establish the content chan...To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis(EDX) is used to establish the content change of oxy- gen in the adhesive in adhesive/carbon fther reinforced epoxy resin composite joints. As water is made up of oxygen and hydrogen, the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints can be obtained from the change in the content of oxygen in the adhesive during humidity aging, via EDX analy-sis. The authors have calculated the water diffusion coefficients and dynamics in the adhesive/carbon fiber reinforced epoxy resin composite joints with the aid of beth energy dispersive X-ray spectroscopy and elemental analysis. The de- termined results with EDX analysis are almost the same as those determined with elemental analysis and the results al- so show that the durability of the adhesive/carbon fther reinforced epoxy resin composite joints subjected to silane cou- pling agent treatment is better than those subjected to sand paper burnishing treatment and chemical oxidation treat- ment.展开更多
Weldability of polyetheretherketone(PEEK) with polyetherimide(PEI) is tested. And carbon fiber reinforced PEEK laminates are resistance welded using stainless steel mesh heating element. The effects of the welding tim...Weldability of polyetheretherketone(PEEK) with polyetherimide(PEI) is tested. And carbon fiber reinforced PEEK laminates are resistance welded using stainless steel mesh heating element. The effects of the welding time and welding pressure on the lap shear strength of joints are investigated. Results show that PEEK can heal with PEI well in welding condition and the lap shear strength of PEEK/CF(carbon fibre) joint increases linearly with welding time, but reaches a maximum value when welding pressure ranging from 0.3 MPa to 0.5 MPa with constant welding time. The fracture characteristics of surface are analyzed by SEM techniques, and four types of fracture modes of lap shear joints are suggested.展开更多
This paper researches ultrasonic vibration drilling of carbon fiber reinforced polymers composites that are hard, brittle, and have low shear strength between layers. An experiment plan has been developed to reduce th...This paper researches ultrasonic vibration drilling of carbon fiber reinforced polymers composites that are hard, brittle, and have low shear strength between layers. An experiment plan has been developed to reduce the axial force. Experimental studies have been done on the influence of process parameters, tool structures on the drilling axial force. The drilling mechanism is specially investigated. Thus an effective method is presented to reduce the drilling axial force. The authors suppose that ultrasonic vibration drilling is feasible for carbon fiber reinforced polymers composites.展开更多
Carbon fiber reinforced thermoplastic composites(CFRTP)and metals hybrid structures have been widely used in aircraft lightweight manufacturing.However,due to the significant difference in physical and chemical proper...Carbon fiber reinforced thermoplastic composites(CFRTP)and metals hybrid structures have been widely used in aircraft lightweight manufacturing.However,due to the significant difference in physical and chemical properties between CFRTP and metals,there are lots of challenges to connect them with high quality.Laser welding has a good application prospect in CFRTP and metals connection,and a significant research progress has been made in the exploration of CFRTP-metal laser joining mechanism,joining process optimization,joining strength improvement and joining defects controlling.However,there are still some problems need to be solved for this technology application.In this paper,the research progress of CFRTP-metal laser joining was summarized in three major aspects:theoretical modeling and simulation analysis,process exploration and parameter optimization,joint performance improvement and process innovation.And,problems and challenges of this technology were discussed,and the outlook of this research was provided.展开更多
The SiC gradiently coated carbon fiber/carbon (Cf/C) composites were prepared by a two-step rapid chemical liquid deposition (RCLD) method. The microstructure and properties of the composites were investigated usi...The SiC gradiently coated carbon fiber/carbon (Cf/C) composites were prepared by a two-step rapid chemical liquid deposition (RCLD) method. The microstructure and properties of the composites were investigated using X-ray diffraction, scanning electron microscopy together with energy dispersive X-ray analysis, bending tests, and oxidation tests. The experimental results show that the surface layer of the composites is composed of SiC, pyrocarbon, and carbon fibers. Their inner area consists of pyrocarbon and carbon fibers. The SiC content gradiently decreases with increasing distance from the outer surface to the center of the composites. Furthermore, the thickness of the SiC layer increases with increasing tetraethylorthosilicate content and deposition time. SiC coatings have no significant influence on the bending strength of the composites. However, the oxidation resistance of the composites increases with increasing thickness of the SiC layer.展开更多
In this work,pitch-based carbon fibers were utilized to reinforce silicon carbide(SiC)composites via reaction melting infiltration(RMI)method by controlling the reaction temperature and resin carbon content.Thermal co...In this work,pitch-based carbon fibers were utilized to reinforce silicon carbide(SiC)composites via reaction melting infiltration(RMI)method by controlling the reaction temperature and resin carbon content.Thermal conductivities and bending strengths of composites obtained under different preparation conditions were characterized by various analytical methods.Results showed the formation of SiC whiskers(SiC_(w))during RMI process according to vapor–solid(VS)mechanism.SiC_(w) played an important role in toughening the C_(pf)/SiC composites due to crack bridging,crack deflection,and SiC_(w) pull-out.Increase in reaction temperature during RMI process led to an initial increase in thermal conductivity along in-plane and thickness directions of composites,followed by a decline.At reaction temperature of 1600℃,thermal conductivities along the in-plane and thickness directions were estimated to be 203.00 and 39.59 W/(m×K),respectively.Under these conditions,bending strength was recorded as 186.15±3.95 MPa.Increase in resin carbon content before RMI process led to the generation of more SiC matrix.Thermal conductivities along in-plane and thickness directions remained stable with desirable values of 175.79 and 38.86 W/(m×K),respectively.By comparison,optimal bending strength improved to 244.62±3.07 MPa.In sum,these findings look promising for future application of pitch-based carbon fibers for reinforcement of SiC ceramic composites.展开更多
Oxidation behaviors of carbon fiber reinforced SiC matrix composites(C/SiC)are one of the most noteworthy properties.For C/SiC,the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coef...Oxidation behaviors of carbon fiber reinforced SiC matrix composites(C/SiC)are one of the most noteworthy properties.For C/SiC,the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coefficients of thermal expansion(CTEs)and elastic modulus between carbon fiber and SiC matrix.In order to improve the oxidation resistance,multilayer SiC–Si_(3)N_(4) matrices were fabricated by chemical vapor infiltration(CVI)to alleviate the above two kinds of mismatch and change the local stress distribution.For the oxidation of C/SiC with multilayer matrices,matrix microcracks would be deflected at the transition layer between different layers of multilayer SiC–Si_(3)N_(4) matrix to lengthen the oxygen diffusion channels,thereby improving the oxidation resistance of C/SiC,especially at 800 and 1000℃.The strength retention ratio was increased from 61.9%(C/SiC–SiC/SiC)to 75.7%(C/SiC–Si_(3)N_(4)/SiC/SiC)and 67.8%(C/SiC–SiC/Si_(3)N_(4)/SiC)after oxidation at 800℃for 10 h.展开更多
In-situ growing carbon nanotubes (CNTs) directly on carbon fibers (CFs) always lead to a degraded tensile strength of CFs and then a poor fiber-dominated mechanical property of carbon/carbon composites (C/ Cs). ...In-situ growing carbon nanotubes (CNTs) directly on carbon fibers (CFs) always lead to a degraded tensile strength of CFs and then a poor fiber-dominated mechanical property of carbon/carbon composites (C/ Cs). To solve this issue, here, a novel carbon fiber-based multiscale reinforcement is reported. To synthesize it, carbon fibers (CFs) have been first grafted by graphene oxide (GO), and then carbon nanotubes (CNTs) have been in-situ grown on GO-grafted CFs by catalytic chemical vapor deposition. Characterizations on this novel reinforcement show that GO grafting cannot only nondestructively improve the surface chemical activity of CFs but also protect CFs against the high-temperature corrosion of metal catalyst during CNT growth, which maintains their tensile properties. Tensile property tests for unidirectional C/Cs with different preforms show that this novel reinforcement can endow C/C with improved tensile properties, 32% and 87% higher than that of pure C/C and C/C only doped with in-situ grown CNTs. This work would open up a possibility to fabricate multiscale C/Cs with excellent global performance.展开更多
Preparing antioxidant coatings to address the inherent oxidation sensitivity of carbon fiber-reinforced carbon aerogel(C/CA)composites is a feasible way to promote their application in oxidizing environments as therma...Preparing antioxidant coatings to address the inherent oxidation sensitivity of carbon fiber-reinforced carbon aerogel(C/CA)composites is a feasible way to promote their application in oxidizing environments as thermal insulation materials.However,preparing the coatings with excellent oxidation and ablation resistance while avoiding evident damage to the C/CA substrate still remains a challenge.Herein,a SiC@SiO_(2)nanowire-toughened ZrB2–SiC/SiC bilayer coating with a large thickness of 500μm was prepared on C/CA using a one-step low-temperature reaction sintering method,which simultaneously formed a sintered outer layer with even-distributed nanowires and a siliconized gradient inner layer.By courtesy of the synergic thermal response of the layers and the crack deflection induced by the nanowires,the resulting coating has moderate residual compressive stress of 0.08–1.22 GPa in the interface,high interfacial bonding strength of 6.02 MPa,and good fracture toughness of 4.36 MPa·m1/2.Benefited from the optimum components and improved structure,the coating shows excellent cyclic ablation resistance with linear ablation rates of 0.1μm/s at 1650℃for 1500 s(300 s×5 cycles)and 0.4μm/s at 1850℃for 900 s(300 s×3 cycles).The one-step preparation strategy contributes to little damage to the substrate,thus showing the well-preserved mechanical and thermal insulation properties.展开更多
Crack of conductive component is one of the biggest threats to daily production. In order to detect the crack on conductive component,the pulsed eddy current thermography models were built according to different mater...Crack of conductive component is one of the biggest threats to daily production. In order to detect the crack on conductive component,the pulsed eddy current thermography models were built according to different materials with the cracks based on finite element method(FEM) simulation. The influence of the induction heating temperature distribution with the different defect depths were simulated for the carbon fiber reinforced plastic(CFRP) materials and general metal materials. The grey value of image sequence was extracted to analyze its relationship with the depth of crack. Simulative and experimental results show that in the carbon fiber reinforced composite materials,the bigger depth of the crack is,the larger temperature rise of the crack during the heating phase is; and the bigger depth of the crack is,the faster the cooling rate of the crack during the cooling phase is. In general metal materials,the smaller depth of the crack is,the lager temperature rise of the crack during the heating phase is; and the smaller depth of the crack is,the faster the cooling rate of crack during the cooling phase is.展开更多
Grid pattern was textured on Ti-6 Al-4 V alloy(TC4)substrate surface by nanosecond laser system.Laser joining of carbon fiber reinforced thermoplastic composite(CFRTP)to TC4 joints were performed,and the effect of tex...Grid pattern was textured on Ti-6 Al-4 V alloy(TC4)substrate surface by nanosecond laser system.Laser joining of carbon fiber reinforced thermoplastic composite(CFRTP)to TC4 joints were performed,and the effect of texture grid depth was investigated.The contact angle of molten CFRTP on textured TC4 surface was measured and the tensile-shear force was tested.The fracture surface and interface morphology were observed.The results indicated that the wettability of molten CFRTP on TC4 surface improved remarkably after laser textured TC4.Shear force of CFRTP/TC4 joints was increased by 156%after laser textured TC4 surface.When the depth of grid was deeper than 100μm,contact angle increased and incomplete filling of molten CFRTP in grid occurred,the shear force thus decreased gradually.Resin-carbon fibers mixture was adhered on the fracture surface of TC4,and the variation tendency of adhesion ratio was consistent with that of shear force.TC4 matrix was exfoliated from substrate and adhered at the fracture surface of CFRTP,indicating stronger mechanical interlocking occurred at the joining interface after laser textured TC4 surface.Beside mechanical interlocking,compound layer consisted of CTi_(0.42)V_(1.58)carburization phase was also confirmed at interface,suggesting that chemical bonding also occurred at the joining interface.展开更多
Carbon fiber reinforced polymer (CFRP) composites have excellent mechanical properties, specifically, high specific stiffness and strength. However, most CFRP composites exhibit poor impact resistance. To overcome thi...Carbon fiber reinforced polymer (CFRP) composites have excellent mechanical properties, specifically, high specific stiffness and strength. However, most CFRP composites exhibit poor impact resistance. To overcome this limitation, this study presents a new plain-woven CFRP composite embedded with superelastic shape memory alloy (SMA) wires. Composite specimens are fabricated using the vacuum-assisted resin injection method. Drop-weight impact tests are conducted on composite specimens with and without SMA wires to evaluate the improvement of impact resistance. The material models of the CFRP composite and superelastic SMA wire are introduced and implemented into a finite element (FE) software by the explicit user-defined material subroutine. FE simulations of the drop-weight impact tests are performed to reveal the superelastic deformation and debonding failure of the SMA inserts. Improvement of the energy absorption capacity and toughness of the SMA-CFRP composite is confirmed by the comparison results.展开更多
基金National High-Tech R&D Program of China(863 Program)(2015AA043401)。
文摘The carbon fiber reinforced composite is a new type of composite material with an excellent property in strength and elastic modulus,and has found extensive applications in aerospace,energy,automotive industry and so on.However,this composite has a strict requirement on processing techniques,for example,brittle damage or delamination often exists in conventional processing techniques.Abrasive water jet machining technology is a new type of green machining technique with distinct advantages such as high-energy and thermal distortion free.The use of abrasive water jet technique to process carbon fiber composite materials has become a popular trend since it can significantly improve the processing accuracy and surface quality of carbon fiber composite materials.However,there are too many parameters that affect the quality of an abrasive water jet machining.At present,few studies are carried out on the parameter optimization of such a machining process,which leads to the unstable quality of surface processing.In this paper,orthogonal design of experiment and regression analysis were employed to establish the empirical model between cutting surface roughness and machining process parameters.Then a verified model was used to optimize the machining process parameters for abrasive water jet cutting carbon fiber reinforced composites.
基金National Natural Science Foundation of China(No.11802192)Natural Science Foundation of Jiangsu Province,China(No.BK20180244)Nantong Science and Technology Project,China(No.JC2019012)。
文摘The fracture toughness of carbon fiber reinforced epoxy composite(CFRP)was investigated through mode I and mode II shaped fracture system in this paper.A novel polyimide with trifluoromethyl groups and grafted nanosilica were used to modify epoxy resin.Effect of modified resin and unmodified resin on fracture toughness of CFRP was compared and discussed.Lay-up angles and thicknesses effects on fracture toughness of composites were also investigated.The fracture toughness of CFRP was obtained through double cantilever beam(DCB)and end notched flexure(ENF)tests.The results showed that the composites prepared by modified resin exhibited high fracture toughness compared with unmodified composites.The fracture toughness value of mode I increased from 1.83 kJ/m2 to 4.55 kJ/m2.The fracture toughness value of mode II increased from 2.30 kJ/m2 to 6.47 kJ/m2.
基金Supported by Commission of Science Technology and Industry for National Defense of China(No.JPPT-115-477).
文摘To determinate the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints, energy dispersive X-ray spectroscopy analysis(EDX) is used to establish the content change of oxy- gen in the adhesive in adhesive/carbon fther reinforced epoxy resin composite joints. As water is made up of oxygen and hydrogen, the water diffusion coefficients and dynamics in adhesive/carben fiber reinforced epoxy resin composite joints can be obtained from the change in the content of oxygen in the adhesive during humidity aging, via EDX analy-sis. The authors have calculated the water diffusion coefficients and dynamics in the adhesive/carbon fiber reinforced epoxy resin composite joints with the aid of beth energy dispersive X-ray spectroscopy and elemental analysis. The de- termined results with EDX analysis are almost the same as those determined with elemental analysis and the results al- so show that the durability of the adhesive/carbon fther reinforced epoxy resin composite joints subjected to silane cou- pling agent treatment is better than those subjected to sand paper burnishing treatment and chemical oxidation treat- ment.
文摘Weldability of polyetheretherketone(PEEK) with polyetherimide(PEI) is tested. And carbon fiber reinforced PEEK laminates are resistance welded using stainless steel mesh heating element. The effects of the welding time and welding pressure on the lap shear strength of joints are investigated. Results show that PEEK can heal with PEI well in welding condition and the lap shear strength of PEEK/CF(carbon fibre) joint increases linearly with welding time, but reaches a maximum value when welding pressure ranging from 0.3 MPa to 0.5 MPa with constant welding time. The fracture characteristics of surface are analyzed by SEM techniques, and four types of fracture modes of lap shear joints are suggested.
文摘This paper researches ultrasonic vibration drilling of carbon fiber reinforced polymers composites that are hard, brittle, and have low shear strength between layers. An experiment plan has been developed to reduce the axial force. Experimental studies have been done on the influence of process parameters, tool structures on the drilling axial force. The drilling mechanism is specially investigated. Thus an effective method is presented to reduce the drilling axial force. The authors suppose that ultrasonic vibration drilling is feasible for carbon fiber reinforced polymers composites.
基金co-supported by the Shenzhen Basic Research projects(JCYJ20200109144604020,JCYJ20200109144608205 and JCYJ20210324120001003)Yangzhou Hanjiang Science and Technology project(HJZ2021003)+1 种基金Ningbo 2025 major projects(2022Z013)Zhejiang basic public welfare research program(LGG20E050009)。
文摘Carbon fiber reinforced thermoplastic composites(CFRTP)and metals hybrid structures have been widely used in aircraft lightweight manufacturing.However,due to the significant difference in physical and chemical properties between CFRTP and metals,there are lots of challenges to connect them with high quality.Laser welding has a good application prospect in CFRTP and metals connection,and a significant research progress has been made in the exploration of CFRTP-metal laser joining mechanism,joining process optimization,joining strength improvement and joining defects controlling.However,there are still some problems need to be solved for this technology application.In this paper,the research progress of CFRTP-metal laser joining was summarized in three major aspects:theoretical modeling and simulation analysis,process exploration and parameter optimization,joint performance improvement and process innovation.And,problems and challenges of this technology were discussed,and the outlook of this research was provided.
基金supported by the National Natural Science Foundation of China (No.50371047)
文摘The SiC gradiently coated carbon fiber/carbon (Cf/C) composites were prepared by a two-step rapid chemical liquid deposition (RCLD) method. The microstructure and properties of the composites were investigated using X-ray diffraction, scanning electron microscopy together with energy dispersive X-ray analysis, bending tests, and oxidation tests. The experimental results show that the surface layer of the composites is composed of SiC, pyrocarbon, and carbon fibers. Their inner area consists of pyrocarbon and carbon fibers. The SiC content gradiently decreases with increasing distance from the outer surface to the center of the composites. Furthermore, the thickness of the SiC layer increases with increasing tetraethylorthosilicate content and deposition time. SiC coatings have no significant influence on the bending strength of the composites. However, the oxidation resistance of the composites increases with increasing thickness of the SiC layer.
基金This work is supported by the National Key R&D Program of China(No.2018YFB1106600)the National Natural Science Foundation of China(Nos.51602257,92060202,51872229,and 51972269)+2 种基金the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology,No.2021-KF-10)the Creative Research Foundation of the Science and Technology on Thermostructural Composite Materials Laboratory(No.JCKYS2020607001)the Shaanxi Province Foundation for Natural Science(No.2020JQ-169).
文摘In this work,pitch-based carbon fibers were utilized to reinforce silicon carbide(SiC)composites via reaction melting infiltration(RMI)method by controlling the reaction temperature and resin carbon content.Thermal conductivities and bending strengths of composites obtained under different preparation conditions were characterized by various analytical methods.Results showed the formation of SiC whiskers(SiC_(w))during RMI process according to vapor–solid(VS)mechanism.SiC_(w) played an important role in toughening the C_(pf)/SiC composites due to crack bridging,crack deflection,and SiC_(w) pull-out.Increase in reaction temperature during RMI process led to an initial increase in thermal conductivity along in-plane and thickness directions of composites,followed by a decline.At reaction temperature of 1600℃,thermal conductivities along the in-plane and thickness directions were estimated to be 203.00 and 39.59 W/(m×K),respectively.Under these conditions,bending strength was recorded as 186.15±3.95 MPa.Increase in resin carbon content before RMI process led to the generation of more SiC matrix.Thermal conductivities along in-plane and thickness directions remained stable with desirable values of 175.79 and 38.86 W/(m×K),respectively.By comparison,optimal bending strength improved to 244.62±3.07 MPa.In sum,these findings look promising for future application of pitch-based carbon fibers for reinforcement of SiC ceramic composites.
基金This work was supported by the National Natural Science Foundation of China(Nos.52072303 and 51821091)the National Science and Technology Major Project(No.J2019-VI-0014-0129)。
文摘Oxidation behaviors of carbon fiber reinforced SiC matrix composites(C/SiC)are one of the most noteworthy properties.For C/SiC,the oxidation behavior was controlled by matrix microcracks caused by the mismatch of coefficients of thermal expansion(CTEs)and elastic modulus between carbon fiber and SiC matrix.In order to improve the oxidation resistance,multilayer SiC–Si_(3)N_(4) matrices were fabricated by chemical vapor infiltration(CVI)to alleviate the above two kinds of mismatch and change the local stress distribution.For the oxidation of C/SiC with multilayer matrices,matrix microcracks would be deflected at the transition layer between different layers of multilayer SiC–Si_(3)N_(4) matrix to lengthen the oxygen diffusion channels,thereby improving the oxidation resistance of C/SiC,especially at 800 and 1000℃.The strength retention ratio was increased from 61.9%(C/SiC–SiC/SiC)to 75.7%(C/SiC–Si_(3)N_(4)/SiC/SiC)and 67.8%(C/SiC–SiC/Si_(3)N_(4)/SiC)after oxidation at 800℃for 10 h.
基金supported by the National Natural Science Foundation of China (Nos.51432008,51502242,U1435202,and 51202194)the Research Fund for the Doctoral Program of Higher Education of China (No.20126102110013)the Key Grant Project of Chinese Ministry of Education (No.313047)
文摘In-situ growing carbon nanotubes (CNTs) directly on carbon fibers (CFs) always lead to a degraded tensile strength of CFs and then a poor fiber-dominated mechanical property of carbon/carbon composites (C/ Cs). To solve this issue, here, a novel carbon fiber-based multiscale reinforcement is reported. To synthesize it, carbon fibers (CFs) have been first grafted by graphene oxide (GO), and then carbon nanotubes (CNTs) have been in-situ grown on GO-grafted CFs by catalytic chemical vapor deposition. Characterizations on this novel reinforcement show that GO grafting cannot only nondestructively improve the surface chemical activity of CFs but also protect CFs against the high-temperature corrosion of metal catalyst during CNT growth, which maintains their tensile properties. Tensile property tests for unidirectional C/Cs with different preforms show that this novel reinforcement can endow C/C with improved tensile properties, 32% and 87% higher than that of pure C/C and C/C only doped with in-situ grown CNTs. This work would open up a possibility to fabricate multiscale C/Cs with excellent global performance.
基金the Defense Industrial Technology Development Program(No.JCKY2021130B007)the National Natural Science Foundation of China(Nos.52272075 and 52188101)+1 种基金the Research Fund of Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2021190)the directional institutionalized scientific research platform relies on China Spallation Neutron Source of Chinese Academy of Sciences,and the National Key R&D Program of China(No.2021YFA1500804).
文摘Preparing antioxidant coatings to address the inherent oxidation sensitivity of carbon fiber-reinforced carbon aerogel(C/CA)composites is a feasible way to promote their application in oxidizing environments as thermal insulation materials.However,preparing the coatings with excellent oxidation and ablation resistance while avoiding evident damage to the C/CA substrate still remains a challenge.Herein,a SiC@SiO_(2)nanowire-toughened ZrB2–SiC/SiC bilayer coating with a large thickness of 500μm was prepared on C/CA using a one-step low-temperature reaction sintering method,which simultaneously formed a sintered outer layer with even-distributed nanowires and a siliconized gradient inner layer.By courtesy of the synergic thermal response of the layers and the crack deflection induced by the nanowires,the resulting coating has moderate residual compressive stress of 0.08–1.22 GPa in the interface,high interfacial bonding strength of 6.02 MPa,and good fracture toughness of 4.36 MPa·m1/2.Benefited from the optimum components and improved structure,the coating shows excellent cyclic ablation resistance with linear ablation rates of 0.1μm/s at 1650℃for 1500 s(300 s×5 cycles)and 0.4μm/s at 1850℃for 900 s(300 s×3 cycles).The one-step preparation strategy contributes to little damage to the substrate,thus showing the well-preserved mechanical and thermal insulation properties.
基金supported by National Natural Science Foundation of China under Grant No. 51107053, 61501483 and 11402264Key Laboratory of Nondestructive Testing (Nanchang Hangkong University) ,Ministry of Education under Grant No ZD201629001+1 种基金National Key Research and Development Program of China (2016YFF0203400)Postgraduate Research & Practice Innovation Program of Jiangsu Provence under Grant No SJCX17_0487
文摘Crack of conductive component is one of the biggest threats to daily production. In order to detect the crack on conductive component,the pulsed eddy current thermography models were built according to different materials with the cracks based on finite element method(FEM) simulation. The influence of the induction heating temperature distribution with the different defect depths were simulated for the carbon fiber reinforced plastic(CFRP) materials and general metal materials. The grey value of image sequence was extracted to analyze its relationship with the depth of crack. Simulative and experimental results show that in the carbon fiber reinforced composite materials,the bigger depth of the crack is,the larger temperature rise of the crack during the heating phase is; and the bigger depth of the crack is,the faster the cooling rate of the crack during the cooling phase is. In general metal materials,the smaller depth of the crack is,the lager temperature rise of the crack during the heating phase is; and the smaller depth of the crack is,the faster the cooling rate of crack during the cooling phase is.
基金financially supported by National Natural Science Foundation of China(No.51875129)。
文摘Grid pattern was textured on Ti-6 Al-4 V alloy(TC4)substrate surface by nanosecond laser system.Laser joining of carbon fiber reinforced thermoplastic composite(CFRTP)to TC4 joints were performed,and the effect of texture grid depth was investigated.The contact angle of molten CFRTP on textured TC4 surface was measured and the tensile-shear force was tested.The fracture surface and interface morphology were observed.The results indicated that the wettability of molten CFRTP on TC4 surface improved remarkably after laser textured TC4.Shear force of CFRTP/TC4 joints was increased by 156%after laser textured TC4 surface.When the depth of grid was deeper than 100μm,contact angle increased and incomplete filling of molten CFRTP in grid occurred,the shear force thus decreased gradually.Resin-carbon fibers mixture was adhered on the fracture surface of TC4,and the variation tendency of adhesion ratio was consistent with that of shear force.TC4 matrix was exfoliated from substrate and adhered at the fracture surface of CFRTP,indicating stronger mechanical interlocking occurred at the joining interface after laser textured TC4 surface.Beside mechanical interlocking,compound layer consisted of CTi_(0.42)V_(1.58)carburization phase was also confirmed at interface,suggesting that chemical bonding also occurred at the joining interface.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.11802243 and 11802241).
文摘Carbon fiber reinforced polymer (CFRP) composites have excellent mechanical properties, specifically, high specific stiffness and strength. However, most CFRP composites exhibit poor impact resistance. To overcome this limitation, this study presents a new plain-woven CFRP composite embedded with superelastic shape memory alloy (SMA) wires. Composite specimens are fabricated using the vacuum-assisted resin injection method. Drop-weight impact tests are conducted on composite specimens with and without SMA wires to evaluate the improvement of impact resistance. The material models of the CFRP composite and superelastic SMA wire are introduced and implemented into a finite element (FE) software by the explicit user-defined material subroutine. FE simulations of the drop-weight impact tests are performed to reveal the superelastic deformation and debonding failure of the SMA inserts. Improvement of the energy absorption capacity and toughness of the SMA-CFRP composite is confirmed by the comparison results.