Efeito da temperatura e da taxa de aquecimento na sinterização do SiC aditivado com Al2O3-Dy2O3 e Al2O3-Yb2O3

Abstract

Compacts of SiC+10 vol.% (Al2O3+Dy2O3) and SiC+10 vol.% (Al2O3+Yb2O3) mixtures were prepared by cold isostatic pressing and sintered for 60 min in a dilatometer at 1800 and 1900°C, applying heating rates of 10, 20 and 30°C/min. An evaluation of the complete sintering cycle indicated that the heating rates did not significantly affect the shrinkage, but that the sintering temperature may be a relevant factor. The compacts sintered at 1900°C showed 9% higher shrinkage, on average, than those sintered at 1800°C. The maximum shrinkage rates of both mixtures occurred at temperatures below the sintering thresholds, temperatures and heating rates. It was also noted that after the formation of the liquid, the mechanisms of particle rearrangement and solution-precipitation were not as fast as those reported in the literature, but were responsible for much of the shrinkage during the sintering cycle.