| 摘要 |
PURPOSE:To obtain the title high-purity alpha-type silicon nitride while simplifying the process and reducing the auxiliary equipment, energy, and work load, by mixing ammonium chloride into metallic silicon powder to nitride the silicon. CONSTITUTION:When metallic silicon powder is directly nitrided to produce silicon nitride, 1-15wt.% ammonium chloride is added to the silicon powder. The lump metallic silicon obtained by the reduction of quartzite with coke at high temp. in a conventional electric furnace is pulverized to 2-100mu, and the pulverized material can be used as the raw material metallic silicon. Ammonium chloride is added to the material, the mixture is mixed n a dry basis by the mixer such as a ribbon blender for about from 5min-3hr, the product is packed in a heat-resistant vessel and brought into contact with N2, NH3, or their gaseous mixture, and the nitriding reaction is carried out at about 1,000-1,500 deg.C for about 20-180min. By this reaction, the impurities such as Al and Ca are removed along with the exhaust gas prior to nitriding, and high-purity alpha-type silicon nitride can be easily obtained.
|
