Si.sub.3 N.sub.4 Ceramic densified using Sc.sub.2 O.sub.3 and SiO.sub.2
US4401768A · kind A · utility
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3Claims
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Key dates
| Filing date | Mar 15, 1982 |
| Grant date | Aug 30, 1983 |
| Priority date | — |
| Expiry date | Mar 15, 2002 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B35/593
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
At least 1 mole % SiO.sub.2 and 1/2 mole % Sc.sub.2 O.sub.3 are used as a densification aid to provide a polyphase silicon nitride ceramic having high creep strength. The composition is within the Si.sub.3 N.sub.4 - Si.sub.2 N.sub.2 O tie line, the Si.sub.3 N.sub.4 - Sc.sub.2 Si.sub.2 O.sub.7 tie line, and the Sc.sub.2 Si.sub.2 O.sub.7 - Si.sub.2 N.sub.2 O tie line in the ternary phase diagram for the Si.sub.3 N.sub.4, SiO.sub.2, Sc.sub.2 O.sub.3 system. The phases in the sintered ceramic are Sc.sub.2 Si.sub.2 O.sub.7, and Si.sub.3 N.sub.2 O, and at least 50 mole % Si.sub.3 N.sub.4.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.