Design Of Highly Conductive Carbon Fiber Reinforced Aluminum Compoites And Study On The Behavior Of Thermal Cycling

The carbon fiber reinforced aluminium composites used in spacecraft control panel support are studied in this paper are,the ambient temperature is range from-60 ? to 120 ?.In this paper,two kinds of carbon fibers,such as M60 and XN90,were used as the reinforcing material,1199 pure aluminum,AlMn_1.2 and Al Mn₃ as the matrix.The composite materials were prepared by pressure infiltration method and annealed at 330 ?³40 ?.The microstructure and phase of carbon fiber reinforced aluminium composites were analyzed by scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and X-ray diffraction?XRD?.The thermal conductivity,thermal expansion performance and bending performance of the materials were tested by laser thermal conductivity meter,thermal effect automatic analyzer and universal material testing machine.The hot and c old cycle was treated by hot and cold impact testing machine.The relationship between the microstructure and properties of the composites and the effect of thermal cycling on the microstructure and properties of the composites were analyzed.Compared with M60 carbon fiber,XN90 carbon fiber has a high graphitization of 91%,graphite layer is relatively large,the sheet is more compact,this structure is conducive to carbon fiber elastic modulus and thermal conductivity.The six kinds of composites prepared by pressure infiltration were homogeneous,and no cracks were found at the interface.Mn elements are segregated at the substrate and interface.TEM observed that the interface of the composites was clean.No fragile phase such as Al₄C₃ The XRD characterization did not reveal the formation of new phases.The thermal conductivity,flexural strength and elastic modulus of M60 reinforced aluminium composites increase first and then decrease with the addition of Mn element.Which M60 reinforced Al Mn_1.2 composite reached the maximum,thermal conductivity 192W/?m·K?,bending strength 1075 MPa,elastic modulus 365 GPa.The thermal conductivity,flexural strength and elastic modulus of XN90 reinforced aluminium composites increase with the increase of Mn content.The XN90 reinforced Al Mn₃ reaches the maximum,the thermal conductivity is 385 W/?m·K?,the flexural strength is 725 MPa,the elastic modulus is 463 GPa.The longitudinal thermal expansion coefficient of Cf / Al composites varies from-1 to 1 ×10-6 / K,with the temperature increases,the coefficient of thermal expansion decreases first and then increases.The thermal expansion coefficients of the different composites are no big difference.The transverse thermal expansion coefficient is between 20²5×10-6/ K,which is much higher than the longitudinal thermal expansion coefficient,and the transverse thermal expansion coefficient increases with the temperature.With the increase of the number of cycles,the interface of the composites gradually sprouted and expanded,The dislocation density of the composites exhibits a fluctuating change.Its thermal conductivity gradually decreased,the bending strength showed a slight increase and then down the basic basically remain unchanged,the coefficient of thermal expansion of the composite remains essentially constant and its trend with temperature is the same as before,the modulus of elasticity is essentially constant.XN90 / Al degrades less than M60 / Al composites after hot and cold cycles.