Thermal plasma synthesis of SiC- Si₃N₄ composite powders from SiCH₃CI₃- NH₃- H₂

Abstract

SiC-Si₃N₄ composite powders were synthesized by introducing trichloromethylsilane, ammonia, and hydrogen into a high-temperature radiofrequency (RF) thermal plasma argon gas. Powders were characterized by XRD, TEM, and FT-IR. Silicon carbide and silicon nitride were formed independently into separate powders. Silicon carbide was formed as β-SiC crystalline powder and silicon nitride was in an amorphous state. The crystalline SiC powders were in the size range of 75 to 200 nm and amorphous Si₃N₄ powders were 5 to 60 nm. When the mole ratio of ammonia to trichloromethylsilane was between 1 and 2, SiC-Si₃N₄ composite powders were formed, and when it was higher than 4, Si₃N₄ powders were formed.