The Study On Preparation And Properties Of SiC Reinforced Aluminum Matrix Composites

SiC particle reinforced aluminum matrix composites have a wide range of applications in the aerospace,automotive,and sports equipment due to their advantages of high elastic modulus,good wear resistance,high dimensional stability,high specific strength.At present,the preparation method of SiC particle reinforced aluminum matrix composites are mechanical mixing method.The method has some advantages of simple process,easy operation,low cost,easy to large-scale industrial production,etc.However,there is a problem that the dispersion of the enhanced phase particles in the composite material is poor,the stirring time is long and the production efficiency is low,has gradually become the bottleneck of the traditional manufacturing industry developmentAccording to reasonable and feasible mixing device which has the function of efficient join SiC particle in this research,SiCp/Al-7%Si composite are selected for the study.The method in this article is composite casting(the method of mechanical stirring semi-solid liquid aluminum),Study the effects of particle uniformly dispersing process and mechanical properties of SiC particles on different preparation process parameters and explore its dispersion mechanism to determine the best preparation process.Combined with XRD,SEM and EDS detection means to analyze the microstructure and interface problems of the composites.Research the impact of different manufacture techniques on the friction and wear properties of aluminum matrix composite,compare with the gray cast iron(HT250),the wear mechanism of aluminum matrix composites was discussed.The manufacture results show that:Under the optimum technological parameters,the good particle dispersion and performance of SiCp/Al-7%Si composite can be short-term and efficient made by the composite casting method,the best particle uniformly dispersing preparation process parameters are:Particle size is 25μm,stirring time is 3min,the addition amount of Particle SiC is 7.5%,the speed of stirring is 2000 r/min;Create a spherical model,at a certain degree of alloy viscosity,the shearing force increases as the stirring speed increases;The turbulence formed by the shear causes the SiC particles to collide with each other under the action of the centripetal force and the self-floating spin,and finally dispersed in the matrix.Mechanical properties of composite materials under different preparation process parameters:the best tensile strength and the brinell hardness of the composites under the addition of SiC is 10%,the particle size of SiC is 10μm and the speed of stirring is 2000r/min that are all significantly higher than those of the matrix material.The fracture structures of the composites as dimples and its mechanism is mainly brittle fracture;Addition of alloying elements Mg reaction to produce Al2O3,MgAl2O4 can effectively improve the wettability between the enhanced phase and the matrix,and no brittle phase formation.The friction and wear results show that:Composite materials prepared by the composite casting method,Compare with the gray cast iron and the base material,Under the optimal process parameters,the wear rate is significantly lower;The friction coefficient is the most stable when the addition of SiC is 7.5%,the speed of stirring is 2000 r/min and the particle size is 10um;The SiCp/Al-7%Si composite present that the fine enhancing phase distributing in Al matrix stand out and become a supporting body.Grinding parts in the surface layer melts at the high temperatures and form a thin transfer layer,playing a role in reducing aluminum body wear and the wear behavior present abrasive wear and adhesive wear.