Interface and thermal shock resistance of SiC fiber/SiC composites

Abstract

Silicon carbide (SiC) has been accepted to have considerable potential as an engineering material for numerous high-temperature applications because of its high high-temperature strength, stiffness, oxidation resistance, and low density. An important material property needed for high-temperature applications is the thermal shock resistance. The thermal stress is generated at the interface between the fiber and matrix due to the large difference in the thermal expansion coefficients of the two components, when the composites are subjected to any temperature change, i.e., during cooling from the processing temperature to room temperature, or during service. The thermal stress has significant effects on the interface sliding stress, matrix cracking stress, and ultimate strength. The thermal shock resistance of the composites is strongly affected by the strength of the interfacial bond between the fiber and matrix and is important for a wide-range of potential applications. In this work, SiC (SCS-6{trademark}) fiber/SiC composites were fabricated by hot pressing at 1700 C in vacuum using an Al sintering additive. The purpose of this study was to investigate the fiber/matrix interface of the composites and to understand the thermal shock resistance of the composites.