The elastic modulus behavior of two Al_2O_3-SiC-SiO_2-C castables containing 10wt% carbon has been evaluated along one thermal cycle (25°C - 1500deg C), in oxidizing atmosphere, using the high temperature ultrasonic technique working in a long bar mode. Additionally, thermodynamic calculations and X-ray diffraction analyses were correlated to the collected results. Although several changes were detected during one heating-cooling cycle, the E values attained at the initial and final step of the tests were similar and the curves presented an hysteresis behavior. The E evolution was related to the decomposition of the hydrated phases, antioxidant reactions, liquid phase viscosity variation and flaw generation in the microstructure.
展开▼
