Thermomechanical Mismatch in Ceramic-Fiber-Reinforced Glass-Ceramic Composites

The thermomechanical relationship between mullite and a lithium aluminosilicate (LAS) glass-ceramic has been studied by a technique of bimaterial dilatometry. The viscoelastic behavior of LAS was found to result in a temperature T rvsl below the glass-transformation temperature T_g at which the interfacial stresses between the materials undergo a reversal in sign. The effect of T rvsl on the high-temperature mechanical properties of mullite or SiC fiber-reinforced glass-ceramic composites is discussed. It is suggested that fiber clamping by the matrix at temperatures between T rvsl and T_g contributes to the brittle, high-temperature behavior of such composites.