Thermal expansion coefficient and wear performance of aluminium/SiC composites with bimodal particle distributions

Abstract

High volume fraction metal matrix composites were produced by infiltration of liquid aluminium into preforms made by mixing and packing SiC particulates having two different average diameters (170 and 16 μm). The maximum particle volume fraction (0.74) was attained for a mixture containing 67% of coarse particles. The variation of particle volume fraction with percentage of coarse particles can be reasonably well understood in terms of a simple model. Experimental results for the threshold pressure indicate that it is mainly determined by the local volume fraction of fine particles, a result which is shown to be compatible with the model used to estimate the particle volume fraction. On the other hand, the coefficient of thermal expansion (CTE) is mainly determined by the total particle volume fraction of the composite. Wear performance was evaluated through sliding wear of the composite against a static alumina ball. The results indicate that, in this case, the key parameter is the coarse particle content of the composite.