| 摘要 |
PURPOSE:To prepare alpha-type Si3N4 having uniform qualities, continuously, by placing powdery or formed Si on a tray made of Si3N4, inserting the tray into a tunnel kiln, and contacting with non-oxidizing gas containing N2 countercurrently under heating. CONSTITUTION:JIS No. 1 metallic Si added with 0.1-10wt% catalyst such as CaF or 5-50wt% Si3N4 is crushed to powder passing through the 100 mesh Tyler sieve, or granulated or formed. One or more raw materials obtained by the above process are placed on a tray made of Si3N4, inserted into a tunnel kiln with countecurrent flow of non-oxidizing gas containing N2, heated gradually from normal temperature, and nitrided at 1,000-1,450 deg.C. The process enables the continuous and automatic preparation of alpha-type Si3N4 under the same nitriding conditions, and gives uniform product having high reliability. |
