Gas pressure sintering of beta SiC-gamma-AlON composite in nitrogen/argon environment

A SiC and gamma AlON system was studied using beta -SIC powder and a preformed spinel between Al2O3 and AlN corresponding to gamma- AlON. A wide range of composition from 10 to 90 wt. % gamma -AlON with beta -SiC was studied. The composite was sintered to near pore-free dense sintered product for a wide range of composition ranging from 10 to 55 wt.% of gamma -AlON content in both a N-2 and an Ar atmosphere under a gas pressure of 6 bar. The effect of sintering atmosphere on the sintered properties such as weight loss, percentage linear shrinkage, percentage apparent porosity, and bulk density of the fired samples were determined. Weight loss of the specimen was 4.3-5.5 wt.% in a nitrogen and 6.2-10.75 wt.% in an Ar atmosphere indicating substantial supression of dissociation reaction during sintering in nitrogen atmosphere. Microhardness of the sintered specimen measured by indentation under a load of 1 N was 16.5-29.81 GPa. Phase analysis by XRD studies and the other properties indicated solid solution formation between SIC and gamma -AlON. (C) 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved.