Method of making densified Si.sub.3 N.sub.4 /oxynitride composite with premixed silicon and oxygen carrying agents

摘要

A method is disclosed for making a more densified silicon nitride comprising object under less stringent heating conditions without sacrificing physical properties. A mixture of silicon powder, 6-18% yttrium silicon oxynitride (a major proportion of which is the Y.sub.10 Si.sub.6 O.sub.24 N.sub.2 phase), 0.4-3% Al.sub.2 O.sub.3, and possibly up to 2% of an oxynitride forming oxide (Y.sub.2 O.sub.3) is compacted, nitrided, and sintered to produce a silicon nitride/YSiO.sub.2 N comprising object of relatively high density.