An evaluation of the strength of a SiC(p)/Al2O3 ceramic matrix composite exposed to coal slag at elevated temperatures

Tubular samples of a silicon carbide particulate reinforced alumina ceramic matrix composite were exposed to Illinois #6 coal slag at temperatures of 1100°C, 1260°C, and 1400°C for a period of 200 hours. Additional samples were held at these same temperatures without the application of slag. Following these expo-sures, the tubes were cut into C-shaped rings for strength testing. The strength testing was performed by compressing the C-rings at the exposure temperatures using an electric resistance furnace fitted to a hydraulic press. Using a finite ele-ment solver coupled to a statistical analysis code, the characteristic strength and Weibull parameter of the material exposed to each of the conditions, was deter-mined. These parameters are used to estimate the probability of failure of a given specimen when subjected to a given set of physical loads. The strength of the material was found to decrease as the temperature of ex-posure was increased, with additional decreases caused by exposure to the coal slag. Furthermore, at 1400°C the highest of the three temperatures, a notice-able amount of the tube material was lost. Based on these data, this material’s maximum usable temperature range in a high-temperature slagging environment is predicted to lie between 1260°C and 1400°C.