Análise de trincas causadas por choque térmico em carbeto de silício

Abstract

The aim of this study is to analyze the formation and propagation of cracks, as well as the occurrence of thermal fatigue in SiC subjected to thermal shock. Samples were prepared with 90%SiC+10%(Y2O3:Al2O3) mole, in the proportions 1:3 and 1:4 of additives. The compacted samples were sintered at 1750 °C, 1850 °C and 1950 °C in graphite resistive furnace. The thermal cycles were performed by heating at two different temperatures (600 °C and 900 °C) in a tubular furnace, and quenched in water. Analysis of cracks was performed by scanning electron microscopy on samples from flexural strength test after 1 and 50 thermal cycles, or after thermal fatigue. The sintering temperature and thermal cycle have a great influence on the formation and propagation of cracks. The samples sintered at 1950 °C, despite having a significant number of cracks, are the only ones not introduce thermal fatigue to 900ºC.