Patent US4119475A successfully refreshed from Google Patents.
US4119475A
Expired / Lapsed
US
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Sintering of silicon nitride using Mg and Be additives
Assignee: General Electric Co
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Filing: 1977-11-07
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Granted: 1978-10-10
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Expires: 1997-11-07
Abstract
Abstract A particulate dispersion of silicon nitride, magnesium additive and beryllium additive is formed into a green body and sintered at a temperature ranging from about 1800° C to about 2200° C in a sintering atmosphere of nitrogen at superatmospheric pressure producing a sintered body with a density ranging from about 80% to about 100%.
Inventors
- 👤 Svante Prochazka
- 👤 Charles D. Greskovich
- 👤 Richard J. Charles
- 👤 Robert A. Giddings
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 09:01
CPC Classifications
H; H01; H01B; H01B3/00; H01B3/02; H01B3/12; C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/5935
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
132 words
A pre-shaped polycrystalline body having a density ranging from at least about 80% to about 100% of the theoretical density of silicon nitride, said body being comprised of silicon nitride, beryllium and magnesium, said silicon nitride ranging from the β-form to at least about 80% by weight of β-form-20% by weight α-form based on the total amount of said silicon nitride, said beryllium ranging in amount from less than about 0.1% by weight to less than about 2.0% by weight of said silicon nitride, said magnesium ranging in amount from less than about 0.5% by weight to less than about 4.0% by weight of the silicon nitride, said polycrystalline body according to X-ray diffraction analysis ranging from a single phase body to one comprised of a primary phase and a secondary phase.
Claim 2
Dependent Claim
132 words
A pre-shaped polycrystalline body having a density ranging from at least about 80% to about 100% of the theoretical density of silicon nitride, said body being comprised of silicon nitride, beryllium and magnesium, said silicon nitride ranging from the β-form to at least about 80% by weight of β-form-20% by weight α-form based on the total amount of said silicon nitride, said beryllium ranging in amount from less than about 0.1% by weight to less than about 2.0% by weight of said silicon nitride, said magnesium ranging in amount from less than about 0.5% by weight to less than about 4.0% by weight of the silicon nitride, said polycrystalline body according to X-ray diffraction analysis ranging from a single phase body to one comprised of a primary phase and a secondary phase.
Claim 3
Dependent Claim
20 words
A pre-shaped polycrystalline body according to claim 1 which according to said X-ray diffraction analysis is a single phase body.
Claim 4
Dependent Claim
16 words
A pre-shaped polycrystalline body according to claim 1 wherein said secondary phase is a beryllium-containing phase.
Claim 5
Dependent Claim
18 words
A pre-shaped polycrystalline silicon nitride body according to claim 1 wherein said secondary phase is a magnesium-containing phase.
Claim 6
Dependent Claim
26 words
A pre-shaped polycrystalline silicon nitride body according to claim 1 which contains oxygen in an amount ranging up to about 2% by weight of said body.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-10-09 | 1982-04-10 | 1982-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-09 | 1986-04-10 | 1986-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-09 | 1990-04-10 | 1990-10-10 | $7700.00 | Window Closed / Lapsed |