| 摘要 |
PROBLEM TO BE SOLVED: To obtainα-type enriched powdery silicon nitride in high purity and yield by carrying out a nitridation reaction by adding powderyα-Fe2 O3 to powdery metallic silicon which is a raw material. SOLUTION: This production of highα-silicon nitride is to add 0.3-2.0 wt.%, preferably 0.5-1.5 wt.% of powderyα-Fe2 O3 having 0.3-20μm average particle size to powdery metallic silicon having 1-50μm, preferably 2-20μm average particle size and containing <=0.2 wt.% of metal impurity content, carry out nitridation reaction in an atmosphere containing 95-80 vol.% nitrogen and 5-20 vol.% hydrogen, under 10-100 mm Ag pressure at 1,250-1,450 deg.C and obtain powdery silicon nitride. Then, this powdery silicon nitride is granulated by a jaw crusher, a roller mill, etc. and pulverized by a dry- or wet-atomizer to the objective particle size. Then, particles are treated with an acid to remove iron silicides, wash and dried. As the acid, a mixed acid of hydrofluoric acid with nitric acid or hydrochloric acid with nitric acid, etc. can be used.
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