Silicon nitride powder and method for producing the same

摘要

The invention relates to a silicon nitride powder used for production of silicon nitride ceramics products. The powder can provide a compact having homogeneous packing structure of powder, constantly and with good reproducibility. To produce the powder of the invention a silicon nitride powder is heat treated in a two-stage process comprising one stage in an inert gas or reducing atmosphere at 100 DEG C-1000 DEG C for 5-600 min., and another stage in an oxidising atmosphere at 300 DEG C-1200 DEG C for 5-600 min. As a result of this treatment, a silicon nitride powder is obtained in which its powder particles are crystalline in their interior and are coated with an amorphous layer having a 1-10 nm surface thickness and composed mainly of Si, N, O, and H, the atomic number ratio of oxygen to nitrogen (O/N) of the surface layer being within a range of 0.1-2.0.