Preparation of h-BN nano-film coated α-Si3N4 composite particles by a chemical route

Abstract

In this study, α-Si₃N₄ particles were successfully coated with h-BN nano-film by a novel chemical route. Ammonium biborate was deposited onto the surface of silicon nitride particles to form NH₄HB₄O₇·3H₂O–Si₃N₄ composite powders by the heterogeneous precipitation method in anhydrous ethanol solution. The obtained composite powders were dried at room temperature, then nitrided in an ammonia flow at 900 °C and subsequently crystallized at 1600 °C to obtain h-BN nano-film coated α-Si₃N₄ composite particles. The prepared composite particles were characterized by IR, SAM, TEM, HRTEM, TG and DSC techniques. TEM and HRTEM micrographs showed that α-Si₃N₄ particles were well coated by BN ultrathin film in thickness of 1 nm.