Damage-Resistant SiC–AlN Layered Composites with Surface Compressive Stresses

Three-layer samples in the SiC-AlN system with outer layers richer in SiC, as well as monolithic samples of uniform composition, were fabricated by hot-pressing. The strain gage technique, previously described, was used to estimate residual compressive stress in the outer layers developed because of the difference in coefficients of thermal expansion between inner and outer layers. Bar-shaped samples were indented using a Vickers indenter under loads as high as 20 kg (196 N) on outer layers and were fractured in three-point bending. Three-layer samples with outer layers under compression exhibited increased resistance to the contact-induced damage in comparison to the monoclinic samples.

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