Sintered body of silicon nitride and method of producing the same
US5756411A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 20, 1996 |
| Grant date | May 26, 1998 |
| Priority date | — |
| Expiry date | Aug 20, 2016 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B35/591
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The invention reduces the time required for nitriding in the process of reaction sintering for production of a sintered body of silicon nitride, thereby improving productivity, and provides a sintered body of silicon nitride having sufficient compactness and high strength which can be produced by reaction sintering. The sintered body is Si.sub.3 N.sub.4 having an unpaired electron density of 10.sup.15 /cm.sup.3 to 10.sup.21 /cm.sup.3. The sintered body is produced through reaction sintering by using a Si powder having an unpaired electron density of 10.sup.15 -10.sup.20 /cm.sup.3, which is obtained by annealing a commercially available Si powder at temperatures of 300.degree. to 800.degree. C. in other than nitrogen atmosphere for 3-5 hours. In particular, the sintered body is produced by adding to the so obtained Si powder, together with a sintering assistant, an element having a valence of, particularly, from +1 to +3, the element having a covalent bond radius RM which bears such a relation with the covalent bond radius RSi of Si that (RM - RSi)/RSi<0.5, or a compound of the element, as a nitrogen hole producing agent, and subjecting the resulting composite to reaction sintering.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.