FRACTURE ENERGY AND MICROSTRUCTURE OF BET A'-SIALON-BN COMPOSITE

Effects of particle size and addition of BN on the fracture energy (ga mma(s)) as well as effective fracture energy (gamma(eff)) of pressurel ess sintered beta'-Sialon-BN composites have been studied, and porosit y, flexural strength, Young's modulus and fracture toughness were eval uated, Results obtained are as follows; comparison of the effect of pa rticle size of BN revealed that the deterioration of mechanical proper ties is smaller for the fine particles of BN, Similarly, gamma(s) is i nsensitive to BN content, while maximum gamma(eff) was observed at 30 mass% addition of fine BN particles, The contribution of nonlinear fra cture energy gamma(R) ( = gamma(eff) - gamma(s)) is related to the pre sence of bar-like crystals in the microstructure of beta'-Sialon-BN co mposite.