In the present study mixtures of conventional alpha-Si3N4 (450nm) with
5, 10, 15, 20wt% beta-SiC(500nm) or nanosized beta-SiC(20nm) and tern
ary Si-C-N (15nm) powders (25, 40wt%SiC) were used as starting materia
ls. Hot isostatic pressing (HIP) of these powders using quartz capsule
s at temperatures above 1800 degrees C and pressures of 200MPa resulte
d in compacts with densities higher than 98% theoretical density. The
influence of SiC content and of the different types of starting powder
s on density, phase transformation, microstructure, hardness and fract
ure toughness is discussed.