High-temperature properties of a silicon nitride/boron nitride nanocomposite

Hexagonal graphitic BN (h-BN) is interesting as a second phase for high-temperature structural ceramics because it has the same crystal structure as graphite, for which fracture strength and Young's modulus increase with increased temperature. In this study, high-temperature mechanical properties of Si₃N₄/BN nanocomposite were evaluated to clarify the effect of fine h-BN particles at elevated temperatures. As a result, we found that high-temperature strength and hardness of the nanocomposite were maintained up to high temperatures; also, its Young's modulus increased gradually, concomitant with elevated temperatures up to 1400 °C. Finally, these properties were compared with those of monolithic Si₃N₄ and Si₃N₄/BN microcomposite.