Thermal Shock Behavior of Two-Dimensional Woven Fiber-Reinforced Ceramic Composites

The thermal shock behavior of three types of two‐dimensional woven, continuous fiber‐reinforced (NextelTM 312 (3M Co., St. Paul, MN) or NicalonTM (Nippon Carbon, Tokyo, Japan)) ceramic matrix (silicon carbide matrix that had been processed by chemical vapor infiltration or polymer impregnation and pyrolysis) composites was studied using the water‐quench technique. Thermal‐shock‐induced damage was characterized by a destructive technique of four‐point flexure and a nondestructive technique of Young's modulus measurement by the dynamic resonance method. Compared with monolithic ceramics, the continuous fiber‐reinforced ceramic composites were capable of preventing catastrophic failure that was caused by thermal shock. Analysis of the results that were based on the stresses that were generated by thermal shock and the mismatch of thermal expansion between fibers and matrices suggested possible mechanisms of the thermal shock damage. Preliminary results showed evidence of matrix cracking and delamination because of the thermal shock damage. The feasibility of using the nondestructive technique to detect thermal shock damage also was demonstrated.