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.