METHOD OF IMPROVING QUALITY OF HOT PRESSED SI.SUB.3N.SUB.4 BODIES

摘要

A method of improving the quality of hot- pressed Si3N4 bodies is disclosed. Unpurified silicon powder and admixed oxygen carrying agents are compacted to form a preform. The preform is heated to agglomerate the mixture to an increased density no greater than 2.7 gm/cm3. The heat treated preform is immersed in one or more stages in one or more leaching solutions of effective concentration to remove selected impurities. The treated preform is then hot pressed to full density accompanied by a reduction of undesirable impurities, such as iron silicide, which conventionally form during hot pressing.