In this paper, the tensile properties of the MWK structures produced with different basic stitches for composite reinforcement were experimentally studied. The results show that the MWK structures with the double loop...In this paper, the tensile properties of the MWK structures produced with different basic stitches for composite reinforcement were experimentally studied. The results show that the MWK structures with the double loop pillar stitches have better mechanical properties.展开更多
This work aims at investigating the microwave absorption and mechanical properties of short-cutted carbon fiber/glass fiber hybrid veil reinforced epoxy composites.The short-cutted carbon fibers(CFs)/glass fibers(GFs)...This work aims at investigating the microwave absorption and mechanical properties of short-cutted carbon fiber/glass fiber hybrid veil reinforced epoxy composites.The short-cutted carbon fibers(CFs)/glass fibers(GFs)hybrid veil were prepared by papermaking technology,and composites liquid molding was employed to manufacture CFs/GFs hybrid epoxy composites.The microstructure,microwave absorbing properties and mechanical properties of the hybrid epoxy composites were studied by using SEM,vector network analyzer and universal material testing,respectively.The reflection coefficient of the composites were calculated by the measured complex permittivity and permeability in the X-band(8.2-12.4 GHz)range.The optimum microwave absorption properties can be obtained when the content of CFs in the hybrid veil is 6 wt%and the thickness of the composites is 2 mm,the minimum reflection coefficient of-31.8 dB and the effective absorption bandwidth is 2.1 GHz,which is ascribed to benefitting impedance matching characteristic and dielectric loss of the carbon fiber.Simultaneously the tensile strength and modulus can achieve 104.0 and 2.98GPa,demonstrating that the CFs/GFs hybrid epoxy composites can be a promising candidate of microwave absorbing materials with high mechanical properties.展开更多
Fibre can enhance the mechanical properties of cement-based composites,but fibre also degrades their workability.However,the quantitative effects of fiber content and length-diameter ratio on alkali-activated material...Fibre can enhance the mechanical properties of cement-based composites,but fibre also degrades their workability.However,the quantitative effects of fiber content and length-diameter ratio on alkali-activated materials are still unclear.Various aspect ratio,volume fraction of polyvinyl alcohol fibre(PVAF),and various water-binder ratio were employed to prepare a total of 26 groups of fibre reinforced alkali-activated composite(FRAAC).The influence of PVAF fibre factor(product of fiber volume fraction and length-diameter ratio)on flowability,compactness,strength,and crack fractal dimension of FRAAC was researched.The influence of water-binder ratio on the plastic viscosity of FRAAC was more significant than that on the yield stress.When fibre factor was lower than critical value of 150,the influence of fibres could be overlooked.The reason was that the space between fibres was distant,so the flowability of FRAAC was not impacted by PVAF.At this time,fibres were challenging to restrict the cracks in matrix and increase their mechanical properties.When fibre factor was higher than critical value 150 and lower than density packing value 450,the flexural strength,compressive strength and crack fractal dimension of FRAAC were considerably enhanced,and the FRAAC could still flow easily under dead weight.When fibre factor were above 450,noteworthy fibre balling considerably decreased the flowability,leading to poor solidity and reduced compressive strength.Hence,the ideal content of PVAF in alkali activated composite is between 150/(l/d)and 450/(l/d).展开更多
To study the static bending creep properties of glass fiber reinforced wood,glass fiber reinforced poplar(GFRP)specimens were obtained by pasting glass fiber on the upper and lower surfaces of Poplar(Populus euramevic...To study the static bending creep properties of glass fiber reinforced wood,glass fiber reinforced poplar(GFRP)specimens were obtained by pasting glass fiber on the upper and lower surfaces of Poplar(Populus euramevicana,P),the performance of Normal Creep(NC)and Mechanical Sorptive Creep(MSC)of GFRP and their influencing factors were tested and analyzed.The test results and analysis show that:(1)The MOE and MOR of Poplar were increased by 17.06%and 10.00%respectively by the glass fiber surface reinforced composite.(2)The surface reinforced P with glass fiber cloth only exhibits the NC pattern of wood and loses the MSC characteristics of wood,regardless of the constant or alternating changes in relative humidity.(3)The instantaneous elastic deformation,viscoelastic deformation,viscous deformation and total creep deflection of GFRP are positively correlated with the stress level of the external load applied to the specimen.Still,the specimen’s creep recovery rate is negatively correlated with the stress level of the external load applied to the specimen.The static creep deflection and viscous deformation of GFRP increase with the increase of the relative humidity of the environment.(4)The MSC maximum creep deflection of GFRP increased by only 7.41%over the NC maximum creep deflection,but the MSC maximum creep deflection of P increased by 199.25%over the NC maximum creep deflection.(5)The Burgers 4-factor model and the Weibull distribution equation can fit the NC and NC recovery processes of GFRP well.展开更多
Synthetic reinforced composites affect the environment adversely and have become a global concern, causing increased natural composite demand for sustainability and cost effectiveness. Glass is a popular material that...Synthetic reinforced composites affect the environment adversely and have become a global concern, causing increased natural composite demand for sustainability and cost effectiveness. Glass is a popular material that is highly consumed in reinforced composites for its superior mechanical strength. As opposed to that, flax obtained from flax stalks can be used as an alternative reinforcing material with synthetic fibers to minimize manmade fiber consumption. Hence, this research work addresses a few flax/glass-reinforced hybrid composites by using a thermoset polyester matrix. Here, six categories of samples are made, like neat flax, neat glass, and flax/glass fabric reinforced hybrid composite, followed by different stacking layer sequences and hand layout techniques during processing. Afterwards, the mechanical behavior, thermal stability, morphological behavior, and water absorption of hybrid samples were investigated. Among the developed samples, neat glass (NG) composite exhibits superior mechanical properties, while neat flax (NF) shows the lowest result. It is apparent that the mechanical properties and thermal stability of hybrid samples are in between NF and NG because, by adding glass with flax fabric, the strength of hybrid samples is increased. Moreover, it is noticeable that, due to multiple stacking layers of flax and glass, hybrid 3 and hybrid 4 show better strength than consecutive single stacking layers in hybrid 1 and hybrid 2. Among all hybrid composites, the H4 shows comparatively better mechanical and thermal properties due to having the glass layers on the outermost surface. In summary, this research work demonstrated the feasibility of flax fabric with glass fabric as a reinforced hybrid composite that can be used in automobile inner bodies, household furnishing, and home interior decoration.展开更多
Synthetic reinforced composites affect the environment adversely and have become a global concern, causing increased natural composite demand for sustainability and cost effectiveness. Glass is a popular material that...Synthetic reinforced composites affect the environment adversely and have become a global concern, causing increased natural composite demand for sustainability and cost effectiveness. Glass is a popular material that is highly consumed in reinforced composites for its superior mechanical strength. As opposed to that, flax obtained from flax stalks can be used as an alternative reinforcing material with synthetic fibers to minimize manmade fiber consumption. Hence, this research work addresses a few flax/glass-reinforced hybrid composites by using a thermoset polyester matrix. Here, six categories of samples are made, like neat flax, neat glass, and flax/glass fabric reinforced hybrid composite, followed by different stacking layer sequences and hand layout techniques during processing. Afterwards, the mechanical behavior, thermal stability, morphological behavior, and water absorption of hybrid samples were investigated. Among the developed samples, neat glass (NG) composite exhibits superior mechanical properties, while neat flax (NF) shows the lowest result. It is apparent that the mechanical properties and thermal stability of hybrid samples are in between NF and NG because, by adding glass with flax fabric, the strength of hybrid samples is increased. Moreover, it is noticeable that, due to multiple stacking layers of flax and glass, hybrid 3 and hybrid 4 show better strength than consecutive single stacking layers in hybrid 1 and hybrid 2. Among all hybrid composites, the H4 shows comparatively better mechanical and thermal properties due to having the glass layers on the outermost surface. In summary, this research work demonstrated the feasibility of flax fabric with glass fabric as a reinforced hybrid composite that can be used in automobile inner bodies, household furnishing, and home interior decoration.展开更多
Pure Cu composites reinforced with diamond particles were fabricated by a high pressure and high temperature (HPHT) infiltration technique. Their microstructural evolution and thermal conductivity were presented as ...Pure Cu composites reinforced with diamond particles were fabricated by a high pressure and high temperature (HPHT) infiltration technique. Their microstructural evolution and thermal conductivity were presented as a function of sintering parameters (temperature, pressure, and time). The improvement in interfacial bonding strength and the maximum thermM conductivity of 750 W/(m.K) were achieved at the optimal sintering parameters of 1200℃, 6 GPa and 10 min. It is found that the thermal conductivity of the composites depends strongly on sintering pressure. When the sintering pressure is above 6 GPa, the diamond skeleton is detected, which greatly contributes to the excellent thermal conductivity.展开更多
The 6351 wrought aluminum alloy and K2TiF6-CaF2-LiCl components were selected as raw materials to fabricate in situ Al3Ti particulate reinforced aluminum alloy at 720℃via direct melt reaction method with electromagne...The 6351 wrought aluminum alloy and K2TiF6-CaF2-LiCl components were selected as raw materials to fabricate in situ Al3Ti particulate reinforced aluminum alloy at 720℃via direct melt reaction method with electromagnetic stirring(EMS).CaF2 and LiCl acted as fluxes to lower the reaction temperature of the system.It is shown that the electromagnetic stirring and fluxes accelerate the emulsion process of K2TiF6.Optical microscopy,scanning electron microscopy,transmission electron microscopy and energy dispersive spectrum were utilized to analyze the microstructure and components of composites.Compared to composites fabricated without EMS and fluxes,the sizes of endogenetic Al3Ti are refined from 10-15μm to 2-4μm,which are often accompanied with silicon element.The morphology of Al3Ti or Al3TiSi0.22 exhibits triangle,quadrilateral and other clumpy patterns. Because of the Ca elements from CaF2,the sizes of Mg2Si decrease from 8-10μm to 1-2μm due to the formation of Ca2Si.展开更多
Particulate reinforced metallic matrix composites have attracted considerable attention due to their lightweight, high strength, high specific modulus, and good wear resistance. A1/B4C composite strips were produced i...Particulate reinforced metallic matrix composites have attracted considerable attention due to their lightweight, high strength, high specific modulus, and good wear resistance. A1/B4C composite strips were produced in this work by a modified accumulative roll bonding process where the strips were rotated 90° around the normal direction between successive passes. Transmission electron microscopy and X-ray diffraction analyses reveal the development of nanostructures in the Al matrix after seven passes. It is found that the B4C reinforcement distribution in the matrix is improved by progression of the process. Additionally, the tensile yield strength and elongation of the processed materials are increased with the increase of passes.展开更多
β-SiC nanoparticle reinforced A1 matrix (nano-SiCp/A1) composite was prepared by a multi- step powder metallurgy strategy including presureless sintering, hot compacting process and hot extrusion. The microstructur...β-SiC nanoparticle reinforced A1 matrix (nano-SiCp/A1) composite was prepared by a multi- step powder metallurgy strategy including presureless sintering, hot compacting process and hot extrusion. The microstructures of the as-prepared composites were observed by scanning electronic microscopy (SEM), and the mechanical properties were characterized by tensile strength measurement and Brinell hardness test. The experimental results revealed that the tensile strength of the composite with the addition of 5wt%/3-SIC nanoprtieles could be increased to 215 MPa, increasing by 110% compared with pure A1 matrix. Comparative experiments reflected that theβ-SIC nanoprticles showed significant reinforcement effect than traditional a-SiC micro-sized particles. The preparation process and sintering procedure were investigated to develop a cost effective preparation strategy to fabricate nano-SiCp/A1 composite.展开更多
A study has been made on diffusion bonding of SiCp/2024Ai composites by means of pure Al interlayer. In the condition of TB=843 K, PB=16 MPa, tB= 60 min, the diffusion bonded joint, with a shear strength of 235 MPa, w...A study has been made on diffusion bonding of SiCp/2024Ai composites by means of pure Al interlayer. In the condition of TB=843 K, PB=16 MPa, tB= 60 min, the diffusion bonded joint, with a shear strength of 235 MPa, was obtained when a 15 μm thick interlayer was used. The results of the shear testing and SEM indicate that fracture of the joint presented characteristics of ductile rupture.展开更多
Dendrocalamus farinosus and Phyllostachys heterocycla bamboo logs were subjected to a novel treat- ment process for the preparation of bamboo fiber mats (BFMs), and the obtained BFM were used to fabricate bamboo fib...Dendrocalamus farinosus and Phyllostachys heterocycla bamboo logs were subjected to a novel treat- ment process for the preparation of bamboo fiber mats (BFMs), and the obtained BFM were used to fabricate bamboo fiber reinforced composite (BFRC). We studied the mechanical properties of the BFRCs manufactured from the mats with and without bamboo nodes. The pres- ence of nodes in BFM greatly reduced tensile strength, compressive strength, modulus of elasticity, and modulus of rupture of the BFRCs, while the BFRCs fabricated from BFMs with nodes possessed higher horizontal shear strength. Therefore, the nodes in bamboo culms were an important factor in the uniform distribution of mechanical properties, and BFMs should be homogeneously arranged to reduce the impact of nodes on the mechanical strengths of BFRCs.展开更多
The present paper continues the discussion in Part I. Model and Formulation. Based on the theory proposed in Part I, the formulae predicting stiffness moduli of the composites in some typical cases of whisker orie...The present paper continues the discussion in Part I. Model and Formulation. Based on the theory proposed in Part I, the formulae predicting stiffness moduli of the composites in some typical cases of whisker orientations and loading conditions are derived and compared with theoretical representatives in literatures, experimental measurement and commonly used empirical formulae. It seems that (1) with whisker reinforcing and matrix hardening considered, the present prediction is in well agreement with the experimental measurement; (2) the present theory can predict accurate moduli with the proper pre calculated parameters; (3) the upper bound and lower bound of the present theory are just the predictions of equal strain theory and equal stress theory; (4) the present theory provides a physical explanation and theoretical base for the present commonly used empirical formulae. Compared with the microscopic mechanical theories, the present theory is competent for modulus prediction of practical engineering composite in accuracy and simplicity. [WT5”HZ]展开更多
The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount o...The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount of data exists on the solid fraction-temperature re- lationship in A356 alloy, information regarding the solid fraction evolution characteristics of A356-TiB2 composites is scarce. The present article establishes the temperature-solid fraction correlation in A356 alloy and A356-xTiB2 (x = 2.5wt% and 5wt%) composites using dif- ferential thermal analysis (DTA). The DTA results indicate that the solidification characteristics of the composites exhibited a variation of 2℃ and 3℃ in liquidus temperatures and a variation of 3℃ and 5℃ in solidus temperatures with respect to the base alloy. Moreover, the eutectic growth temperature and the solid fraction(fs) vs. temperature characteristics of the composites were found to be higher than those of the base alloy. The investigation revealed that in-situ formed TiB2 particles in the molten metal introduced more nucleation sites and reduced undercooling.展开更多
Based on the study of strain distribution in short-fiber/whisker reinforced metal matrix composites, a deformation characteristic parameter λ is defined as the ratio of the root-mean-square strain of reinforcers to t...Based on the study of strain distribution in short-fiber/whisker reinforced metal matrix composites, a deformation characteristic parameter λ is defined as the ratio of the root-mean-square strain of reinforcers to the macro-linear strain along the same direction. Quantitative relation between λ and microstructure parameters of the composite is obtained. As an example of applying and verifying λ, the stress-strain curve of [AlBO]w/Al composite under tensile loading is predicted and favorably compared with experiments. By using λ, the stiffness modulus of the composite with arbitrary reinforcer orientation under any loading condition is predicted from the microstructure parameters of material.展开更多
In order to study themechanical properties of Z-pins reinforced laminated composite single-lap adhesively bonded joint under un-directional static tensile load,damage failure analysis of the joint was carried out byme...In order to study themechanical properties of Z-pins reinforced laminated composite single-lap adhesively bonded joint under un-directional static tensile load,damage failure analysis of the joint was carried out bymeans of test and numerical simulation.The failure mode and mechanism of the joint were analyzed by tensile failure experiments.According to the experimental results,the joint exhibits mixed failure,and the ultimate failure is Z-pins pulling out of the adherend.In order to study the failure mechanism of the joint,the finite element method is used to predict the failure strength.The numerical results are in good agreement with the experimental results,and the error is 6.0%,which proves the validity of the numerical model.Through progressive damage failure analysis,it is found that matrix tensile failure of laminate at the edge of Z-pins occurs first,then adhesive layer failure-proceeds at the edge of Z-pins,and finally matrix-fiber shear failure of the laminate takes place.With the increase of load,the matrix-fiber shear failure expands gradually in the X direction,and at the same time,the matrix tensile failure at the hole edge gradually extends in different directions,which is consistent with the experimental results.展开更多
Effects of diffusion welding parameters on strength of welded joint based on particle reinforced alumini- um matrix composite Al2O3p/6061Al were studied by comparing with aluminium matrix alloy,Mecha- nism for ...Effects of diffusion welding parameters on strength of welded joint based on particle reinforced alumini- um matrix composite Al2O3p/6061Al were studied by comparing with aluminium matrix alloy,Mecha- nism for the loss of joint strength was analyzed.It was pointed out that the key processing parameters affecting the strength of joint was the welding temperature.The high quality joint can be successfully obtained with appropriate diffusion welding parameters.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
The fabrication of copper (Cu) and copper matrix silicon carbide (Cu/SiCp) particulate composites via the sinter-forging process was investigated. Sintering and sinter-forging processes were performed under an ine...The fabrication of copper (Cu) and copper matrix silicon carbide (Cu/SiCp) particulate composites via the sinter-forging process was investigated. Sintering and sinter-forging processes were performed under an inert Ar atmosphere. The influence of sinter-forging time, temperature, and compressive stress on the relative density and hardness of the prepared samples was systematically investigated and subsequently compared with that of the samples prepared by the conventional sintering process. The relative density and hardness of the composites were enhanced when they were prepared by the sinter-forging process. The relative density values of all Cu/SiCp composite samples were observed to decrease with the increase in SiC content.展开更多
文摘In this paper, the tensile properties of the MWK structures produced with different basic stitches for composite reinforcement were experimentally studied. The results show that the MWK structures with the double loop pillar stitches have better mechanical properties.
基金Funded by Key Research and Development Plan in Hubei Province of China(Nos.2022BCA082,2022BCA077,2021BCA153)Initial Scientific Research Fund for High-level Talents of Hubei University of Technology(No.GCRC2020017)。
文摘This work aims at investigating the microwave absorption and mechanical properties of short-cutted carbon fiber/glass fiber hybrid veil reinforced epoxy composites.The short-cutted carbon fibers(CFs)/glass fibers(GFs)hybrid veil were prepared by papermaking technology,and composites liquid molding was employed to manufacture CFs/GFs hybrid epoxy composites.The microstructure,microwave absorbing properties and mechanical properties of the hybrid epoxy composites were studied by using SEM,vector network analyzer and universal material testing,respectively.The reflection coefficient of the composites were calculated by the measured complex permittivity and permeability in the X-band(8.2-12.4 GHz)range.The optimum microwave absorption properties can be obtained when the content of CFs in the hybrid veil is 6 wt%and the thickness of the composites is 2 mm,the minimum reflection coefficient of-31.8 dB and the effective absorption bandwidth is 2.1 GHz,which is ascribed to benefitting impedance matching characteristic and dielectric loss of the carbon fiber.Simultaneously the tensile strength and modulus can achieve 104.0 and 2.98GPa,demonstrating that the CFs/GFs hybrid epoxy composites can be a promising candidate of microwave absorbing materials with high mechanical properties.
基金funding of Henan Province Transportation Science and Technology Plan Project(2021J3).
文摘Fibre can enhance the mechanical properties of cement-based composites,but fibre also degrades their workability.However,the quantitative effects of fiber content and length-diameter ratio on alkali-activated materials are still unclear.Various aspect ratio,volume fraction of polyvinyl alcohol fibre(PVAF),and various water-binder ratio were employed to prepare a total of 26 groups of fibre reinforced alkali-activated composite(FRAAC).The influence of PVAF fibre factor(product of fiber volume fraction and length-diameter ratio)on flowability,compactness,strength,and crack fractal dimension of FRAAC was researched.The influence of water-binder ratio on the plastic viscosity of FRAAC was more significant than that on the yield stress.When fibre factor was lower than critical value of 150,the influence of fibres could be overlooked.The reason was that the space between fibres was distant,so the flowability of FRAAC was not impacted by PVAF.At this time,fibres were challenging to restrict the cracks in matrix and increase their mechanical properties.When fibre factor was higher than critical value 150 and lower than density packing value 450,the flexural strength,compressive strength and crack fractal dimension of FRAAC were considerably enhanced,and the FRAAC could still flow easily under dead weight.When fibre factor were above 450,noteworthy fibre balling considerably decreased the flowability,leading to poor solidity and reduced compressive strength.Hence,the ideal content of PVAF in alkali activated composite is between 150/(l/d)and 450/(l/d).
基金The present work was financially sponsored by the National Natural Science Foundation of China(Grant No.31960291).
文摘To study the static bending creep properties of glass fiber reinforced wood,glass fiber reinforced poplar(GFRP)specimens were obtained by pasting glass fiber on the upper and lower surfaces of Poplar(Populus euramevicana,P),the performance of Normal Creep(NC)and Mechanical Sorptive Creep(MSC)of GFRP and their influencing factors were tested and analyzed.The test results and analysis show that:(1)The MOE and MOR of Poplar were increased by 17.06%and 10.00%respectively by the glass fiber surface reinforced composite.(2)The surface reinforced P with glass fiber cloth only exhibits the NC pattern of wood and loses the MSC characteristics of wood,regardless of the constant or alternating changes in relative humidity.(3)The instantaneous elastic deformation,viscoelastic deformation,viscous deformation and total creep deflection of GFRP are positively correlated with the stress level of the external load applied to the specimen.Still,the specimen’s creep recovery rate is negatively correlated with the stress level of the external load applied to the specimen.The static creep deflection and viscous deformation of GFRP increase with the increase of the relative humidity of the environment.(4)The MSC maximum creep deflection of GFRP increased by only 7.41%over the NC maximum creep deflection,but the MSC maximum creep deflection of P increased by 199.25%over the NC maximum creep deflection.(5)The Burgers 4-factor model and the Weibull distribution equation can fit the NC and NC recovery processes of GFRP well.
文摘Synthetic reinforced composites affect the environment adversely and have become a global concern, causing increased natural composite demand for sustainability and cost effectiveness. Glass is a popular material that is highly consumed in reinforced composites for its superior mechanical strength. As opposed to that, flax obtained from flax stalks can be used as an alternative reinforcing material with synthetic fibers to minimize manmade fiber consumption. Hence, this research work addresses a few flax/glass-reinforced hybrid composites by using a thermoset polyester matrix. Here, six categories of samples are made, like neat flax, neat glass, and flax/glass fabric reinforced hybrid composite, followed by different stacking layer sequences and hand layout techniques during processing. Afterwards, the mechanical behavior, thermal stability, morphological behavior, and water absorption of hybrid samples were investigated. Among the developed samples, neat glass (NG) composite exhibits superior mechanical properties, while neat flax (NF) shows the lowest result. It is apparent that the mechanical properties and thermal stability of hybrid samples are in between NF and NG because, by adding glass with flax fabric, the strength of hybrid samples is increased. Moreover, it is noticeable that, due to multiple stacking layers of flax and glass, hybrid 3 and hybrid 4 show better strength than consecutive single stacking layers in hybrid 1 and hybrid 2. Among all hybrid composites, the H4 shows comparatively better mechanical and thermal properties due to having the glass layers on the outermost surface. In summary, this research work demonstrated the feasibility of flax fabric with glass fabric as a reinforced hybrid composite that can be used in automobile inner bodies, household furnishing, and home interior decoration.
文摘Synthetic reinforced composites affect the environment adversely and have become a global concern, causing increased natural composite demand for sustainability and cost effectiveness. Glass is a popular material that is highly consumed in reinforced composites for its superior mechanical strength. As opposed to that, flax obtained from flax stalks can be used as an alternative reinforcing material with synthetic fibers to minimize manmade fiber consumption. Hence, this research work addresses a few flax/glass-reinforced hybrid composites by using a thermoset polyester matrix. Here, six categories of samples are made, like neat flax, neat glass, and flax/glass fabric reinforced hybrid composite, followed by different stacking layer sequences and hand layout techniques during processing. Afterwards, the mechanical behavior, thermal stability, morphological behavior, and water absorption of hybrid samples were investigated. Among the developed samples, neat glass (NG) composite exhibits superior mechanical properties, while neat flax (NF) shows the lowest result. It is apparent that the mechanical properties and thermal stability of hybrid samples are in between NF and NG because, by adding glass with flax fabric, the strength of hybrid samples is increased. Moreover, it is noticeable that, due to multiple stacking layers of flax and glass, hybrid 3 and hybrid 4 show better strength than consecutive single stacking layers in hybrid 1 and hybrid 2. Among all hybrid composites, the H4 shows comparatively better mechanical and thermal properties due to having the glass layers on the outermost surface. In summary, this research work demonstrated the feasibility of flax fabric with glass fabric as a reinforced hybrid composite that can be used in automobile inner bodies, household furnishing, and home interior decoration.
基金supported by the National Natural Science Foundation of China (No. 50971020)the National High-Tech Research and Development Program of China (No. 2008AA03Z505)
文摘Pure Cu composites reinforced with diamond particles were fabricated by a high pressure and high temperature (HPHT) infiltration technique. Their microstructural evolution and thermal conductivity were presented as a function of sintering parameters (temperature, pressure, and time). The improvement in interfacial bonding strength and the maximum thermM conductivity of 750 W/(m.K) were achieved at the optimal sintering parameters of 1200℃, 6 GPa and 10 min. It is found that the thermal conductivity of the composites depends strongly on sintering pressure. When the sintering pressure is above 6 GPa, the diamond skeleton is detected, which greatly contributes to the excellent thermal conductivity.
基金Project(2007AA03Z548)supported by the National High-Tech Research and Development Program of ChinaProject(207038)supported by the Key Program of Ministry of Education of China+3 种基金Project(06-D-021)supported by the Talents Peak in Six Key Fields of Jiangsu Province in ChinaProject(07JDG084)supported by the Technical Enablement Foundation for the Super Special Talents of Jiangsu UniversityProject(20071108)supported by the Technical Enablement Foundation of Ministry of Education for the Returned ScholarsProject(20060299006)supported by the PhD Programs Foundation of Ministry of Education of China
文摘The 6351 wrought aluminum alloy and K2TiF6-CaF2-LiCl components were selected as raw materials to fabricate in situ Al3Ti particulate reinforced aluminum alloy at 720℃via direct melt reaction method with electromagnetic stirring(EMS).CaF2 and LiCl acted as fluxes to lower the reaction temperature of the system.It is shown that the electromagnetic stirring and fluxes accelerate the emulsion process of K2TiF6.Optical microscopy,scanning electron microscopy,transmission electron microscopy and energy dispersive spectrum were utilized to analyze the microstructure and components of composites.Compared to composites fabricated without EMS and fluxes,the sizes of endogenetic Al3Ti are refined from 10-15μm to 2-4μm,which are often accompanied with silicon element.The morphology of Al3Ti or Al3TiSi0.22 exhibits triangle,quadrilateral and other clumpy patterns. Because of the Ca elements from CaF2,the sizes of Mg2Si decrease from 8-10μm to 1-2μm due to the formation of Ca2Si.
文摘Particulate reinforced metallic matrix composites have attracted considerable attention due to their lightweight, high strength, high specific modulus, and good wear resistance. A1/B4C composite strips were produced in this work by a modified accumulative roll bonding process where the strips were rotated 90° around the normal direction between successive passes. Transmission electron microscopy and X-ray diffraction analyses reveal the development of nanostructures in the Al matrix after seven passes. It is found that the B4C reinforcement distribution in the matrix is improved by progression of the process. Additionally, the tensile yield strength and elongation of the processed materials are increased with the increase of passes.
基金Funded by the Research Collaborative Innovation Project of Jiangsu Province,China(BY2009129)the Science and Technology Project of Suzhou,China(SYG0905)
文摘β-SiC nanoparticle reinforced A1 matrix (nano-SiCp/A1) composite was prepared by a multi- step powder metallurgy strategy including presureless sintering, hot compacting process and hot extrusion. The microstructures of the as-prepared composites were observed by scanning electronic microscopy (SEM), and the mechanical properties were characterized by tensile strength measurement and Brinell hardness test. The experimental results revealed that the tensile strength of the composite with the addition of 5wt%/3-SIC nanoprtieles could be increased to 215 MPa, increasing by 110% compared with pure A1 matrix. Comparative experiments reflected that theβ-SIC nanoprticles showed significant reinforcement effect than traditional a-SiC micro-sized particles. The preparation process and sintering procedure were investigated to develop a cost effective preparation strategy to fabricate nano-SiCp/A1 composite.
基金the National Advanced Technology "863" Project of China with !No.715-005-0800
文摘A study has been made on diffusion bonding of SiCp/2024Ai composites by means of pure Al interlayer. In the condition of TB=843 K, PB=16 MPa, tB= 60 min, the diffusion bonded joint, with a shear strength of 235 MPa, was obtained when a 15 μm thick interlayer was used. The results of the shear testing and SEM indicate that fracture of the joint presented characteristics of ductile rupture.
基金financially supported by the Key Laboratory of Wood Industry and Furniture Engineering of Sichuan Provincial Colleges and Universitiesthe National Forestry Public Welfare Scientific Research Program(201304503)the Science and Technology Innovation Foundation for College Students
文摘Dendrocalamus farinosus and Phyllostachys heterocycla bamboo logs were subjected to a novel treat- ment process for the preparation of bamboo fiber mats (BFMs), and the obtained BFM were used to fabricate bamboo fiber reinforced composite (BFRC). We studied the mechanical properties of the BFRCs manufactured from the mats with and without bamboo nodes. The pres- ence of nodes in BFM greatly reduced tensile strength, compressive strength, modulus of elasticity, and modulus of rupture of the BFRCs, while the BFRCs fabricated from BFMs with nodes possessed higher horizontal shear strength. Therefore, the nodes in bamboo culms were an important factor in the uniform distribution of mechanical properties, and BFMs should be homogeneously arranged to reduce the impact of nodes on the mechanical strengths of BFRCs.
基金National Natural Science Foundation of China !( 19870 2 65 ,1973 2 0 60 ) Chinese Academ y of Sciences Foundation
文摘The present paper continues the discussion in Part I. Model and Formulation. Based on the theory proposed in Part I, the formulae predicting stiffness moduli of the composites in some typical cases of whisker orientations and loading conditions are derived and compared with theoretical representatives in literatures, experimental measurement and commonly used empirical formulae. It seems that (1) with whisker reinforcing and matrix hardening considered, the present prediction is in well agreement with the experimental measurement; (2) the present theory can predict accurate moduli with the proper pre calculated parameters; (3) the upper bound and lower bound of the present theory are just the predictions of equal strain theory and equal stress theory; (4) the present theory provides a physical explanation and theoretical base for the present commonly used empirical formulae. Compared with the microscopic mechanical theories, the present theory is competent for modulus prediction of practical engineering composite in accuracy and simplicity. [WT5”HZ]
基金financial support from the Indian Institute of Technology Bhubaneswar under the SEED project grant for fabricating the "cooling slope casting" experimental setupthe support extended by Central Research Facility (CRF), Indian Institute of Technology Kharagpur, toward the facility for conducting DTA experiments
文摘The key factor in semi-solid metal processing is the solid fraction at the forming temperature because it affects the microstructure and mechanical properties of the thixoformed components. Though an enormous amount of data exists on the solid fraction-temperature re- lationship in A356 alloy, information regarding the solid fraction evolution characteristics of A356-TiB2 composites is scarce. The present article establishes the temperature-solid fraction correlation in A356 alloy and A356-xTiB2 (x = 2.5wt% and 5wt%) composites using dif- ferential thermal analysis (DTA). The DTA results indicate that the solidification characteristics of the composites exhibited a variation of 2℃ and 3℃ in liquidus temperatures and a variation of 3℃ and 5℃ in solidus temperatures with respect to the base alloy. Moreover, the eutectic growth temperature and the solid fraction(fs) vs. temperature characteristics of the composites were found to be higher than those of the base alloy. The investigation revealed that in-situ formed TiB2 particles in the molten metal introduced more nucleation sites and reduced undercooling.
基金National Natural Science Foundation of China (19872 0 6 5 19732 0 6 0 ) Chinese Academy of Sciences Foundation (KJ95 1-1-2
文摘Based on the study of strain distribution in short-fiber/whisker reinforced metal matrix composites, a deformation characteristic parameter λ is defined as the ratio of the root-mean-square strain of reinforcers to the macro-linear strain along the same direction. Quantitative relation between λ and microstructure parameters of the composite is obtained. As an example of applying and verifying λ, the stress-strain curve of [AlBO]w/Al composite under tensile loading is predicted and favorably compared with experiments. By using λ, the stiffness modulus of the composite with arbitrary reinforcer orientation under any loading condition is predicted from the microstructure parameters of material.
基金supported by Natural Science Talents Program of Lingnan Normal University(No.ZL2021011).
文摘In order to study themechanical properties of Z-pins reinforced laminated composite single-lap adhesively bonded joint under un-directional static tensile load,damage failure analysis of the joint was carried out bymeans of test and numerical simulation.The failure mode and mechanism of the joint were analyzed by tensile failure experiments.According to the experimental results,the joint exhibits mixed failure,and the ultimate failure is Z-pins pulling out of the adherend.In order to study the failure mechanism of the joint,the finite element method is used to predict the failure strength.The numerical results are in good agreement with the experimental results,and the error is 6.0%,which proves the validity of the numerical model.Through progressive damage failure analysis,it is found that matrix tensile failure of laminate at the edge of Z-pins occurs first,then adhesive layer failure-proceeds at the edge of Z-pins,and finally matrix-fiber shear failure of the laminate takes place.With the increase of load,the matrix-fiber shear failure expands gradually in the X direction,and at the same time,the matrix tensile failure at the hole edge gradually extends in different directions,which is consistent with the experimental results.
文摘Effects of diffusion welding parameters on strength of welded joint based on particle reinforced alumini- um matrix composite Al2O3p/6061Al were studied by comparing with aluminium matrix alloy,Mecha- nism for the loss of joint strength was analyzed.It was pointed out that the key processing parameters affecting the strength of joint was the welding temperature.The high quality joint can be successfully obtained with appropriate diffusion welding parameters.
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The fabrication of copper (Cu) and copper matrix silicon carbide (Cu/SiCp) particulate composites via the sinter-forging process was investigated. Sintering and sinter-forging processes were performed under an inert Ar atmosphere. The influence of sinter-forging time, temperature, and compressive stress on the relative density and hardness of the prepared samples was systematically investigated and subsequently compared with that of the samples prepared by the conventional sintering process. The relative density and hardness of the composites were enhanced when they were prepared by the sinter-forging process. The relative density values of all Cu/SiCp composite samples were observed to decrease with the increase in SiC content.