POSTIRRADIATION FIBER DEBONDING AND PULL-OUT IN SIC-SIC COMPOSITES

The toughness of ceramic matrix composites is contributed by crack bri dging, matrix crack deflection, fiber debonding and pull-out and other minor effects. Crack bridging relies on fibers being intact close to the crack tip, while pull-out toughening relies on the debonding and f rictional characteristics of the fiber-matrix interface. The interface friction depends on the interface pressure (i.e., on misfit strains) and interface roughness. In this paper, a calculational model for post irradiation fiber debonding and pull-out toughness in SiC-SiC composit es is presented. It is shown that fiber debonding and pull-out toughne ss in SiC-SiC composites vary significantly with neutron fluence and i rradiation temperature, which is a direct consequence of the dependenc e of the misfit strain on these irradiation variables.