Al{sub}2O{sub}3-SiC NANOCOMPOSITES BY INFILTRATION OF ALUMINA MATRIX WITH A LIQUID POLYCARBOSILANE

摘要

A polycarbosilane-based SiC-precursor with high ceramic yield was used for the preparation of Al{sub}2O{sub}3-SiC nanocomposites. The pre-sintered alumina matrix was infiltrated with a liquid precursor and subsequently heat treated under controlled conditions in inert atmosphere (Ar), in order to facilitate the ceramisation of the precursor, outgassing of the pyrolysis products and densification of the composites. The volume fraction, and grain size of the SiC particles were controlled by the volume fraction of open pores in the pre-sintered alumina matrix and by the concentration of the solution of the polymer used for the infiltration. The nanocomposites with densities ranging between 93 to 96% of the theoretical density, and with the volume fraction of SiC ranging between 3 and 8 wt %, and with SiC particles in nanometer range distributed within a fine-grained alumina matrix, were prepared by pressureless sintering at 1750°C and characterized by SEM and XRD. The microstructural features were discussed with respect to the applied experimental conditions.