Thermal Shock Resistance of an AlN–BN–SiC Ceramic
Mechanical and thermal properties of AlN–BN–SiC (ABS) ceramics were used to calculate the R, R′, and R″″ thermal shock parameters. The R parameter values ranged from ∼400° to 450°C. Specimens were thermal shocked by water quenching and the critical quench temperatures (ΔTC) were compared with those of a baseline SiC composition. The behavior of the ABS was predicted by R parameter calculations while the behavior of the baseline material was predicted by the R′ calculations due to its higher thermal conductivity (87 W·(m·K)-1) as compared with the ABS materials (∼30 W·(m·K)−1). The highest critical quench temperature for ABS was ∼415°C with the lowest at 360°C, while the critical quench temperature for the baseline material was 450°C. Using temperature dependent data over an appropriate temperature range (room temperature to the predicted ΔTC), the R parameters of the ABS materials were within 15°C of predictions. The baseline material was ∼1.7 times higher than predicted and this was attributed to the high-thermal conductivity of the material resulting in soft thermal shock during quench testing.
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