Manufacture of alpha-type silicon nitride powder

Abstract

Abstract PURPOSE: To obtain α-type silicon nitride powder of high purity by well mixing silica powder of a predetermined grain size and a predetermined amount of carbon powder, granulating the mixed powder to a predetermined grain size, heating the granules at a predetermined temp. or below, and allowing them to contact to an N 2 or N 2 -H 2 mixed gas stream. CONSTITUTION: Silica powder of ≤1μ average grain size is mixed with 0.4W1.4 times as much carbon powder as the theoretical amount for oxygen reduction, and the mixed powder is granulated to ≤1cm, preferably ≤1mm grain size. The granules are reacted at ≤1,500°C in an N 2 or H 2 -N 2 mixed gas stream in a carbon heating furnace. For example, rotary cylinder 1 enclosed with heat insulating material 7 in case 3 and provided with central carbon heater 2 is rotated with driving mechanism 4. Starting material granules are changed into cylinder 1 from hopper 5 and agitated in an N 2 gas stream for 20min while keeping cylinder 1 at 1,400°C with heater 2 by supplying an electric current to Cu electrodes 8. Reaction is then carried out at 1,450°C in an NH 3 gas stream. Thus, desired α-type Si 3 N 4 is obtd. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Masaya Miyake
• 👤 Akio Hara

Bibliographic Details