Boron Nitride Dispersed Nanocomposites with High Thermal Shock Resistance

  • Kusunose, T. (Institute of Scientific and Industrial Research, Osaka University) ;
  • Sekino, T. (Institute of Scientific and Industrial Research, Osaka University) ;
  • Choa, Y.H. (Division of New Materials Engineering, Chonbuk National University) ;
  • Nakayama, T. (Institute of Scientific and Industrial Research, Osaka University) ;
  • Niihara, K. (Institute of Scientific and Industrial Research, Osaka University)
  • Published : 2001.09.01

Abstract

The microstructure and mechanical properties of $Si_3N_4/BN $nanocomposites synthesized by chemical processing were investigated. The nanocomposites containing 15 vol% hexagonal BN (h-BN) were fabricated by hot-pressing $\alpha-Si_3N_4$powders covered with turbostratic BN (t-BN). The t-BN coating on $\alpha-Si_3N_4$particles was prepared by heating $\alpha-Si_3N_4$ particles covered with a mixture of boric acid and urea in hydrogen gas. TEM observations of this nanocomposite revealed that nano-sized h-BN particles were homogeneously dispersed within $Si_3N_4$grains as well as at grain boundaries. The strength and thermal shock resistance were significantly improved in comparison with the $Si_3N_4/BN$ microcomposites.

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