Purifying method for alpha-type silicon nitride

Abstract

Abstract PURPOSE:To remove iron, calcium, silicon and silicon oxide as impurities from fine alpha-type silicon nitride powder by treating the powder with a mineral acid having a prescribed concn. or by further treating the treated powder with a mixed acid consisting of hydrofluoric acid and nitric acid under heating. CONSTITUTION:An aqueous soln. of a mineral acid having >=5% concn. is added to fine alpha-type silicon nitride powder, and the powder is treated under heating. The soln. is then separated from the treated powder. After further adding an aqueous soln. of a mixed acid consisting of hydrofluoric acid and nitric acid to the powder, the powder may be treated again under heating. Thus, iron, calcium, silicon and silicon oxide as impurities are removed from the alpha-type silicon nitride.

Inventors

• 👤 Yozo Kuranari
• 👤 倉成　洋三
• 👤 Nobuyuki Hashimoto
• 👤 信行 橋本

Bibliographic Details