Research On Preparation And Properties Of High Volume Fraction SiC Particle Reinforced Aluminum Matrix Composites

Lightweight is one of the key technologies in development of high speed trains in our country. As the substitute of iron and steel, development of new lightweight materials shows theoretical and practical significance. The weight of brake disc is an important part of vehicle unsuspended weight. The application of aluminum matrix composite on brake discs for high speed train can significantly reduce the unsuspended weight. Considering the requirement of lightweight of brake discs, a SiCp/A356aluminum matrix composite which has high volume fraction of40percent SiC particle was prepared using the vacuum semi-solid stirring casting in this paper.In this paper, the preparation process of40vol.%SiCp/A356aluminum matrix composites was studied."Dilution method", which is used for the preparation of derived material, was proposed in this paper. Various derived aluminum matrix composites with less than40vol.%SiC particle can be prepared by using the "compensation method". It can be achieved by adding different amount of compensation aluminum alloy to the prepared high SiC content aluminum matrix composites and then mixed together. The mechanical properties and quality of the composite material prepared by using the traditional stirring method and the "compensation method" were compared. The compared composites were with3different SiC content, which were10vol.%,20vol.%and30vol.%. The results showed that:When the composite was prepared by stirring at the speed of1200rpm for30minutes at580℃, the particles were well dispersed in the matrix by metallographic observation. The bond between SiC particles and matrix was strong. The porosity of composite materials was0.88%. Grain size of the matrix alloy became finer by adding the grain refining agent of0.7wt%, and SiC particles were better dispersed.Comparing with the traditional stirring method, the mechanical properties and quality of composite material made by the "dilution method" were better. A "deviation dilution effect" was found in respect of SiC particle content and porosity of the composite material. When the SiC content was lower, the SiC particle content deviation and porosity of composite materials became lower. The derived materials whose SiC content were20vol.%showed the best comprehensive mechanical properties. The tensile strength was296MPa, the elongation was1.08%, and the hardness was121.5HB. The fracture surface showed that the fracture mechanism of the composite materials mainly dominated by the fracture of particles and tear of matrix. In this paper, aluminum matrix composites whose SiC content was40vol.%were prepared. The preparation process was studied and a new preparation method,"dilution method", was proposed for processing the aluminum matrix composites. The advantages of this method were analyzed by comparing with traditional processing method.