Preparation Of CNTs-SiC Composite Particles And Its Effect On Properties Of Aluminum Matrix Composites

Carbon Nanotubes(CNTs)reinforced Aluminum Matrix Composites(AMCs)is expected to improve the mechanical properties,thermal conductivity and other physical properties.However,uniform dispersaion and the control of the interfacial reaction between CNTs and A1 are the technical difficulty.In order to solve the above problems,in this paper CNTs-SiC composite particle was prepared by synthetic nano-SiC on CNTs surface,to reduce the specific surface area of CNTs,to promote the dispersion of CNTs in AMCs and to improve the interface compatibility between CNTs and Al matrix.The dense CNTs-SiC/Al composites were prepared by the method of Wet Ball Milling-Spark Plasma Sintering(SPS)-Hot Extusion.And the effects of CNTs-SiC content on the densification behavior,microstructure evolution,thermal properties and mechanical properties of AMCs were investigated.First,by the method of solution mixing,to add lwt%(total powders mass)dispersant(PVP),CNTs and Si powders was uniformly mixed with mechanical stirring and ultrasonic dispersion.The effects of different heat treatment temperatures on the reaction between CNTs-Si and the formation of CNTs-SiC composite reinforced phase structure and phase composition were studied,CNTs-SiC composite particle with relatively uniform SiC layer on the surface of CNTs were prepared.On this basis,the CNTs-SiC/Al mixture powders was prepared by wet ball milling.In the sintering process of 40 MPa and hold 1 h at 630℃,the mixture powders was sintered by SPS.The result show that AMCs can obtain the relative density above 99%,realizing densification.Microanalysis shows that CNTs-SiC sliding rearrangement,an oriented arrangement is formed on a horizontal plane perpendicular to the direction of pressure,forming a composite configuration of composite materials and it is beneficial to exert the high thermal conductivity of CNTs-SiC in axial direction.The results show that AMCs were fabricated by the method of wet ball milling-SPS,with the increase of CNTs-SiC content,the CNTs-SiC/Al can still be dense.Whereas the control group of CNTs/Al and SiC/Al,the relative density appears to be decreasing.The XRD of AMCs show that the synthetic nano-SiC on CNTs surface can effectively restrain CNTs/Al interfacial reaction,reducing interfacial the product Al4C3.The above factors provide a feasible plan for the excellent performance of CNTs in AMCs.Comparing with CNTs reinforced AMCs,CNTs-SiC/Al not only achieve densification with the higher addition of nano-reinforcement(5-15vol%),and maintain well thermal and electricity conductivity.With the increase of CNTs-SiC content,continuously improve the AMCs plastic deformation resistance and improve the hardness of composites,its yield strength(YS)and ultimate tensile strength(UTS)showed a trend of increasing first and then decreasing,when its content is 10 vol%;the YS and UTS of AMCs respectively reach the maximum,it was respectively 145MPa and 208MPa,which were increased 80%and 97%compare with pure Al.At 100 ℃,the CTE of 5vol%CNTs-SiC/Al、10vol%CNTs-SiC/Al and 15vol%CNTs-SiC/Al were reduced 12.65%、13.9%and 19.5%compare with pure Al.The dimple morphology manifest that the frature mechanism of CNTs-SiC/Al composites is combined by cleavage frature and microporous connection.The CNTs-SiC distributed in the fracture dimples of Al matrix,it acts as a bridge between the grains of Al matrix,in the loaded state,the load effectively is transferred from the matrix to the reinforcement by inhibiting the plastic deformation of A1 matrix and consuming crack fracture energy,at last attain reinforcement to pure Al.