Two kinds of unidirectional PAN M40 carbon fiber （55%, volume fraction） reinforced 6061Al and 5A06Al composites were fabricated by the squeeze-casting technology and their interface structure and thermal expansion p...Two kinds of unidirectional PAN M40 carbon fiber （55%, volume fraction） reinforced 6061Al and 5A06Al composites were fabricated by the squeeze-casting technology and their interface structure and thermal expansion properties were investigated. Results showed that the combination between aluminum alloy and fibers was well in two composites and interface reaction in M40/5A06Al composite was weaker than that in M40/6061Al composite. Coefficients of thermal expansion （CTE） of M40/Al composites varied approximately from （1.45-2.68）×10^-6 K^-1 to （0.35-1.44）×10^-6 K^-1 between 20℃ and 450℃, and decreased slowly with the increase of temperature. In addition, the CTE of M40/6061Al composite was lower than that of M40/SA06Al composite. It was observed that fibers were protruded significantly from the matrix after thermal expansion, which demonstrated the existence of interface sliding between fiber and matrix during the thermal expansion. It was believed that weak interracial reaction resulted in a higher CTE. It was found that the experimental CTEs were closer to the predicted values by Schapery model.展开更多
Effective manipulations of thermal expansion and conductivity are significant for improving operational performances of protective coatings,thermoelectric,and radiators.This work uncovers determinant mechanisms of the...Effective manipulations of thermal expansion and conductivity are significant for improving operational performances of protective coatings,thermoelectric,and radiators.This work uncovers determinant mechanisms of the thermal expansion and conductivity of symbiotic ScTaO_(4)/SmTaO_(4) composites as thermal/environmental barrier coatings(T/EBCs),and we consider the effects of interface stress and thermal resistance.The weak bonding and interface stress among composite grains manipulate coefficient of thermal expansion(CTE)stretching from 6.4×10^(−6) to 10.7×10^(−6) K^(−1) at 1300℃,which gets close to that of substrates in T/EBC systems.The multiscale effects,including phonon scattering at the interface,mitigation of the phonon speed(vp),and lattice point defects,synergistically depress phonon thermal transports,and we estimate the proportions of different parts.The interface thermal resistance(R)reduces the thermal conductivity(k)by depressing phonon speed and scattering phonons because of different acoustic properties and weak bonding between symbiotic ScTaO_(4) and SmTaO_(4) ceramics in the composites.This study proves that CTE of tantalates can be artificially regulated to match those of different substrates to expand their applications,and the uncovered multiscale effects can be used to manipulate thermal transports of various materials.展开更多
The silicon-based material exhibits a high theoretical specific capacity and is one of the best anode for the next generation of advanced lithium-ion batteries(LIBs).However,it is difficult for the silicon-based anode...The silicon-based material exhibits a high theoretical specific capacity and is one of the best anode for the next generation of advanced lithium-ion batteries(LIBs).However,it is difficult for the silicon-based anode to form a stable solid-state interphase(SEI)during Li alloy/de-alloy process due to the large volume change(up to 300%)between silicon and Li4.4Si,which seriously limits the cycle life of the LIBs.Herein,we use strontium fluoride(SrF_(2))particle to coat the silicon-carbon(Si/C)electrode(SrF_(2)@Si/C)to help forming a stable and high mechanical strength SEI by spontaneously embedding the SrF_(2) particle into SEI.Meanwhile the formed SEI can inhibit the volume expansion of the silicon-carbon anode during the cycle.The electrochemical test results show that the cycle performance and the ionic conductivity of the SrF_(2)@Si/C anode has been significantly improved.The X-ray photoelectron spectroscopy(XPS)analysis reveals that there are fewer electrolyte decomposition products formed on the surface of the SrF_(2)@Si/C anode.This study provides a facile approach to overcome the problems of Si/C electrode during the electrochemical cycling,which will be beneficial to the industrial application of silicon-based anode materials.展开更多
System architecture is presented for an automatic measurement of thermal expansion. The dynamic measurement of the temperature and thermal expansion displacement of the material is carried out through the application ...System architecture is presented for an automatic measurement of thermal expansion. The dynamic measurement of the temperature and thermal expansion displacement of the material is carried out through the application of Labview. The expansion and temperature of material is stored and displayed in real-time. Then the thermal expansion coefficient can be obtained. The measure- ment system composes of SIOS-SP120D laser interferometer, high vacuum furnace, rbh8223h data acquisition card, rbhS104 conditioning board, constant computer power supply. The USB interface is adopted to collect the temperature and displacement data. Experimental results show that the system has high measurement accuracy and good man-machine interface properties.展开更多
This work aims to describe the behavior of the interface using the method of load transfer between fiber and matrix in a composite material. Our contribution is to track the Evolution of the thermomechanical behavior ...This work aims to describe the behavior of the interface using the method of load transfer between fiber and matrix in a composite material. Our contribution is to track the Evolution of the thermomechanical behavior by establishing a new mathematical model that describes the variation of shear stress along the interface. This model has been implemented in code in C++. The results revealed that the shear of the interface increases with temperature. This increase is partly due to the difference in expansion coefficient between fiber and matrix. The composite studied is T300/914;Carbon-Epoxy.展开更多
The problems of finite bimaterial plates, hearing uniform tension, compact: tension and three point bending, are studied by using the eigenfunction expansion variation method (EEVM). And interfacial stress intensity f...The problems of finite bimaterial plates, hearing uniform tension, compact: tension and three point bending, are studied by using the eigenfunction expansion variation method (EEVM). And interfacial stress intensity factors (SIFs) are determined. The SIFs varying with shear modulus mu and Poisson's ratios nu of both materials are discussed.展开更多
Graphite fiber reinforced magnesium matrix(Grf/Mg)composites were fabricated by squeeze casting technology.M40 graphite fibers were reinforced to AZ91D and ZM6,their thermal expansion behaviors of M40/AZ91D and M40/ZM...Graphite fiber reinforced magnesium matrix(Grf/Mg)composites were fabricated by squeeze casting technology.M40 graphite fibers were reinforced to AZ91D and ZM6,their thermal expansion behaviors of M40/AZ91D and M40/ZM6 composites in the temperature range from 20 to 490℃were investigated.The results show that the interfacial species and thermal stress have significant influence on the thermal expansion behavior of the composites.Simultaneously,the longitudinal coefficient of thermal expansion of Grf/Mg composites are affected by the thermal stress,interfacial species and yield strength of matrix alloy,it also decreases with increasing temperature and descending rate of longitudinal coefficient of thermal expansion(CTEs)of Grf/Mg composites changed in different temperature ranges.In terms of different descending rates,the curve of coefficient of thermal expansion vs temperature can be divided into three stages.The matrix alloys M40/AZ91D and M40/ZM6 yield at 170 and 155℃in the thermal expansion,respectively.展开更多
基金Project(DL09BB23) supported by the Fundamental Research Funds for the Central Universities in China
文摘Two kinds of unidirectional PAN M40 carbon fiber （55%, volume fraction） reinforced 6061Al and 5A06Al composites were fabricated by the squeeze-casting technology and their interface structure and thermal expansion properties were investigated. Results showed that the combination between aluminum alloy and fibers was well in two composites and interface reaction in M40/5A06Al composite was weaker than that in M40/6061Al composite. Coefficients of thermal expansion （CTE） of M40/Al composites varied approximately from （1.45-2.68）×10^-6 K^-1 to （0.35-1.44）×10^-6 K^-1 between 20℃ and 450℃, and decreased slowly with the increase of temperature. In addition, the CTE of M40/6061Al composite was lower than that of M40/SA06Al composite. It was observed that fibers were protruded significantly from the matrix after thermal expansion, which demonstrated the existence of interface sliding between fiber and matrix during the thermal expansion. It was believed that weak interracial reaction resulted in a higher CTE. It was found that the experimental CTEs were closer to the predicted values by Schapery model.
基金Thanks for the supports from the National Natural Science Foundation of China(No.91960103)National Key Research and Development Program of China(No.2022YFB3708600)+1 种基金the Rare and Precious Metals Material Genetic Engineering Project of Yunnan Province(No.202102AB080019-1)the Top Innovative Talents of Graduate Students of Kunming University of Science and Technology。
文摘Effective manipulations of thermal expansion and conductivity are significant for improving operational performances of protective coatings,thermoelectric,and radiators.This work uncovers determinant mechanisms of the thermal expansion and conductivity of symbiotic ScTaO_(4)/SmTaO_(4) composites as thermal/environmental barrier coatings(T/EBCs),and we consider the effects of interface stress and thermal resistance.The weak bonding and interface stress among composite grains manipulate coefficient of thermal expansion(CTE)stretching from 6.4×10^(−6) to 10.7×10^(−6) K^(−1) at 1300℃,which gets close to that of substrates in T/EBC systems.The multiscale effects,including phonon scattering at the interface,mitigation of the phonon speed(vp),and lattice point defects,synergistically depress phonon thermal transports,and we estimate the proportions of different parts.The interface thermal resistance(R)reduces the thermal conductivity(k)by depressing phonon speed and scattering phonons because of different acoustic properties and weak bonding between symbiotic ScTaO_(4) and SmTaO_(4) ceramics in the composites.This study proves that CTE of tantalates can be artificially regulated to match those of different substrates to expand their applications,and the uncovered multiscale effects can be used to manipulate thermal transports of various materials.
基金financially supported by the National Natural Science Foundation of China(No.52072322)the Department of Science and Technology of Sichuan Province,China(Nos.2019YFG0220 and 2019-GH02-00052-HZ).
文摘The silicon-based material exhibits a high theoretical specific capacity and is one of the best anode for the next generation of advanced lithium-ion batteries(LIBs).However,it is difficult for the silicon-based anode to form a stable solid-state interphase(SEI)during Li alloy/de-alloy process due to the large volume change(up to 300%)between silicon and Li4.4Si,which seriously limits the cycle life of the LIBs.Herein,we use strontium fluoride(SrF_(2))particle to coat the silicon-carbon(Si/C)electrode(SrF_(2)@Si/C)to help forming a stable and high mechanical strength SEI by spontaneously embedding the SrF_(2) particle into SEI.Meanwhile the formed SEI can inhibit the volume expansion of the silicon-carbon anode during the cycle.The electrochemical test results show that the cycle performance and the ionic conductivity of the SrF_(2)@Si/C anode has been significantly improved.The X-ray photoelectron spectroscopy(XPS)analysis reveals that there are fewer electrolyte decomposition products formed on the surface of the SrF_(2)@Si/C anode.This study provides a facile approach to overcome the problems of Si/C electrode during the electrochemical cycling,which will be beneficial to the industrial application of silicon-based anode materials.
文摘System architecture is presented for an automatic measurement of thermal expansion. The dynamic measurement of the temperature and thermal expansion displacement of the material is carried out through the application of Labview. The expansion and temperature of material is stored and displayed in real-time. Then the thermal expansion coefficient can be obtained. The measure- ment system composes of SIOS-SP120D laser interferometer, high vacuum furnace, rbh8223h data acquisition card, rbhS104 conditioning board, constant computer power supply. The USB interface is adopted to collect the temperature and displacement data. Experimental results show that the system has high measurement accuracy and good man-machine interface properties.
文摘This work aims to describe the behavior of the interface using the method of load transfer between fiber and matrix in a composite material. Our contribution is to track the Evolution of the thermomechanical behavior by establishing a new mathematical model that describes the variation of shear stress along the interface. This model has been implemented in code in C++. The results revealed that the shear of the interface increases with temperature. This increase is partly due to the difference in expansion coefficient between fiber and matrix. The composite studied is T300/914;Carbon-Epoxy.
文摘The problems of finite bimaterial plates, hearing uniform tension, compact: tension and three point bending, are studied by using the eigenfunction expansion variation method (EEVM). And interfacial stress intensity factors (SIFs) are determined. The SIFs varying with shear modulus mu and Poisson's ratios nu of both materials are discussed.
文摘Graphite fiber reinforced magnesium matrix(Grf/Mg)composites were fabricated by squeeze casting technology.M40 graphite fibers were reinforced to AZ91D and ZM6,their thermal expansion behaviors of M40/AZ91D and M40/ZM6 composites in the temperature range from 20 to 490℃were investigated.The results show that the interfacial species and thermal stress have significant influence on the thermal expansion behavior of the composites.Simultaneously,the longitudinal coefficient of thermal expansion of Grf/Mg composites are affected by the thermal stress,interfacial species and yield strength of matrix alloy,it also decreases with increasing temperature and descending rate of longitudinal coefficient of thermal expansion(CTEs)of Grf/Mg composites changed in different temperature ranges.In terms of different descending rates,the curve of coefficient of thermal expansion vs temperature can be divided into three stages.The matrix alloys M40/AZ91D and M40/ZM6 yield at 170 and 155℃in the thermal expansion,respectively.
