Sintered body of silicon nitride and its manufacture
US5045513A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 1989 |
| Grant date | Sep 3, 1991 |
| Priority date | — |
| Expiry date | Aug 15, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B35/5935
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A sintered body of silicon nitride with high density, strength, toughness, and hardness, which can be used for a structural part of an engine, etc. The sintered body of the invention includes 80 to 94 wt % Si.sub.3 N.sub.4, 2 to 10 wt % Mg compound calculated in MgO equivlent, and 2 to 10 wt % Y compound calculated in Y.sub.2 O.sub.3 equivalent. The Si.sub.3 N.sub.4 contains 5 to 40% .alpha.-phase. The sintered body is manufactured in the following steps: (a) mixing powdery Si.sub.3 N.sub.4 with a Mg compound and a Y compound in the above proportions, and then molding the mixture in which the Si.sub.3 N.sub.4 powder contains 80% or more .alpha.-phase and its grains are 1 .mu.m or less in diameter on average; (b) performing primary sintering at 1,600.degree. C. or less in an atmospher of nitrogen or of an inert gas at 20 atm or less; and (c) performing secondary sintering at 1,400.degree. to 1,600.degree. C. in an atmosphere of nitrogen or of an inert gas at 300 atm or more.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.