MAS-content dependence of the texture and fracture behavior of h-BN-MAS composite ceramics

Texturing was employed to tailor the mechanical properties of h-BN ceramic with MAS as liquid texturing aid. Effects of MAS content on the texture behavior, densification behavior, bending strength, fracture toughness and the fracture behavior of the h-BN ceramics were studied. Moderate MAS of 30 wt% can significantly facilitate the orientation of h-BN grains in the direction perpendicular to the hot-pressing direction. MAS is also in favor of the densification behavior of h-BN as sintering aid. In-situ mechanical testing shows that texturing can greatly improve the mechanical properties and avoid the catastrophic fracture of the h-BN ceramics, and the textured h-BN ceramics exhibit distinct rising R-curve behavior, which is primarily attributed to the effect of parallel-aligned h-BN grains to the crack propagation under loading.