Crack bridging by SiC fibers during slow crack growth and the resultant fracture toughness of SiCSiCf composites

Ceramic matrix composites show the uncommon and promising property of increasing their toughness and maintaining their load-carrying capacity with increasing matrix crack lengths under conditions of subcritical crack growth (SCG). As the crack grows, formation of a more extensive bridging zone allows it to withstand far greater stress intensities than would be expected from fracture tests. Crack bifurcation possibly contributes to this effect but is not likely to be the primary cause. The results of these tests are encouraging and expand the possible uses of these types of materials in applications that require long-term stability under stress.