On CTE of SPS consolidated SiC p /Al composites with various particle size distributions

Abstract

The coefficient of thermal expansion (CTE) of spark plasma sintering consolidated SiC_p/Al composites with various size distributions was investigated with the combination of experimental measurements and modelling analyses. The CTE of the composites decreased with increasing particle volume fraction, and large particles played a major role in the decline of CTE. The measured CTE lay between the predictions of Kerner model and Schapery lower bound, but the possible formation of percolating particle network and the influence of matrix plasticisation led to the slight deviation of the experimental values from model predictions. A CTE peak appeared for all the composites with increasing temperature to about 250–300°C due to the action of matrix plasticisation filling the microvoids in the composites. The composites with mixed particles of substantially different sizes were prone to concentrate thermal stresses on large particles, which induced an early appearance of matrix plastic deformation that can result in a comparably low CTE peak temperature.