Preparation Process And Performance Of SiC Particulate Aluminum Matrix Composites

Particle reinforced aluminum matrix composites (PRAMMCs)show many excellent characteristics such as low coefficient of expansion,high strength，good wear resistance and good thermal stability ratio, and the preparation process is relatively simple, processing technology is more mature, more affordable. It is almost as close to net-shape materials. There has a fast development and application in the high-tech field of aerospace, automotive, and electronics. In this paper SiC PRAMMCs were prepared by the traditional powder metallurgy(P/M) method, which is atomized aluminum powder obtained in6061as the base material, SiC particles as reinforcing phase, and discuss the effect of the temperature, particle size or particle volume fraction to the properties of materials during the preparation process.This experiment were conducted using640℃,645℃,650℃as sintering temperature, then by comparise the condition of the samples which were polished slightly by a fine sandpaper to analyze the effects of the temperature to the samples during the sintering. Experimental results show that the higher sintering temperature causes some melted component to exudates out of the samples’ surface which has a low melting point by the cold residual stresses. Alloy decreased in the surface which resulting the phenomenon of "impervious burning"640℃is the optimum sintering temperature of this experiment.Prepare particle reinforced aluminum matrix composites with SiC particles as reinforcement which is different size. Reinforcement agglomeration was found after analyzed the density, tensile strength and metallurgical phase diagram of the samples which has different size reinforcement. It derived from the data that for the40μm particle size of6061aluminum alloy matrix that the volume fraction of5%of the SiC particles uniformly distributed is8.3μm which is the smallest particle size.Through comparative analysis the density, hardness, tensile strength and other properties of the SiC particle reinforced aluminum matrix composite before and after the hot extrusion, the mechanical properties of composites has been improved by the addition of SiC particles. SiC particles are more uniform distribution in the matrix after hot extrusion, and improve the mechanical properties of the composites effectively.Study the hardness and tensile strength of the material which has the volume fraction of SiC particles changed, and through the analysis of its fracture, it turns out that the maximum hardness of the composite material is97.6HBS, when the particle volume fraction of SiC is15%, the maximum tensile strength of the composite material is284.56Mpa when SiC particle volume fraction is20%.Through the study of the effect of SiC particles’ volume fraction to the thermal expansion coefficient of composite materials, it show that the linear expansion coefficient of the composite increases as the volume fraction of SiC particles decreases, the minimum coefficient of linear expansion is17.710-6/K when the volume fraction of SiC is25%.