Stress Concentration Due to Fiber‐Matrix Fusion in Ceramic‐Matrix Composites

Stress concentration in ceramic‐matrix composites due to fiber‐matrix fusion is investigated using finite‐element modeling (FEM) in conjunction with experiment. FEM results indicate substantial stress concentration can be expected when the fiber and matrix are locally fused. The focus of the investigation is sealing through the formation of a reaction product layer (e.g., SiO 2 in a SiC‐SiC system). Direct sealing also is considered. Tensile experiments involving a novel SiC‐SiC microcomposite system confirm FEM predictions and unambiguously indicate the observed reduction in load‐bearing capacity is the result of a SiO 2 reaction product that locally fuses the fiber and matrix.