Patent US4545652A successfully refreshed from Google Patents.
Patent US4023975A successfully refreshed from Google Patents.
US4023975A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Hot pressed silicon carbide containing beryllium carbide
Assignee: General Electric Co
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Filing: 1975-11-17
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Granted: 1977-05-17
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Expires: 1995-11-17
Abstract
Abstract A dense polycrystalline silicon carbide body is produced by hot pressing a particulate mixture of silicon carbide and beryllium carbide.
Inventors
- 👤 Svanite Prochazka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:04
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565; C04B35/575
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
85 words
A method of preparing a polycrystalline silicon carbide body having a density of at least 98% of the theoretical density of silicon carbide comprising admixing silicon carbide particles with an amount of beryllium carbide particles ranging from 0.1% by weight to 1.5% by weight of said silicon carbide to form a mixture, said particles ranging from submicron size to 5 microns, and hot pressing the resulting particulate mixture at a temperature ranging from 1850° C to 2300° C under a minimum pressure of 3000 psi.
Claim 2
Independent Claim
85 words
A method of preparing a polycrystalline silicon carbide body having a density of at least 98% of the theoretical density of silicon carbide comprising admixing silicon carbide particles with an amount of beryllium carbide particles ranging from 0.1% by weight to 1.5% by weight of said silicon carbide to form a mixture, said particles ranging from submicron size to 5 microns, and hot pressing the resulting particulate mixture at a temperature ranging from 1850° C to 2300° C under a minimum pressure of 3000 psi.
Claim 3
Dependent Claim
14 words
A method according to claim 1 wherein said silicon carbide particles are α-silicon carbide.
Claim 4
Dependent Claim
14 words
A method according to claim 1 wherein said silicon carbide particles are β-silicon carbide.
Claim 5
Dependent Claim
19 words
A method according to claim 1 wherein said silicon carbide particles are a mixture of α- and β-silicon carbides.
Claim 6
Dependent Claim
34 words
A method according to claim 1 wherein particles of elemental carbon of submicron size in an amount ranging from 0.1% to 1% by weight of said silicon carbide are admixed to form said mixture.
Claim 7
Dependent Claim
72 words
A method according to claim 1 wherein a carbonaceous additive is admixed to form said mixture, said additive being heat-decomposible at a temperature ranging from 50° C to 1000° C to produce elemental carbon of submicron size, said additive being used in an amount equivalent to 0.1% by weight to 1.0% by weight of elemental carbon based on said silicon carbide, and pyrolyzing the formed mixture to produce elemental carbon in situ.
Claim 8
Dependent Claim
120 words
A polycrystalline silicon carbide body having a significantly uniform microstructure with a grain size ranging up to 50 microns and a density ranging from 98% to 100% of the density of silicon carbide, said body consisting essentially of silicon carbide and beryllium carbide, said silicon carbide being composed of from 50% by weight to 100% by weight of α-silicon carbide with the remainder being β-silicon carbide, said beryllium carbide being present in an amount ranging from 0.1% by weight to 1.5% by weight of the total amount of said silicon carbide, a minor portion of said beryllium carbide being in solid solution with said silicon carbide with the remainder being in the form of grains of a beryllium carbide phase.
Claim 9
Dependent Claim
120 words
A polycrystalline silicon carbide body having a significantly uniform microstructure with a grain size ranging up to 50 microns and a density ranging from 98% to 100% of the density of silicon carbide, said body consisting essentially of silicon carbide and beryllium carbide, said silicon carbide being composed of from 50% by weight to 100% by weight of α-silicon carbide with the remainder being β-silicon carbide, said beryllium carbide being present in an amount ranging from 0.1% by weight to 1.5% by weight of the total amount of said silicon carbide, a minor portion of said beryllium carbide being in solid solution with said silicon carbide with the remainder being in the form of grains of a beryllium carbide phase.
Claim 10
Dependent Claim
45 words
A polycrystalline silicon carbide body according to claim 7 wherein particles of elemental carbon of substantially submicron size in an amount ranging from 0.1% by weight to 1% by weight of the total amount of said silicon carbide are distributed substantially uniformly throughout said body.
Claim 11
Dependent Claim
27 words
A polycrystalline silicon carbide body according to claim 7 having a P-type semiconductivity with a resistivity in air at room temperature ranging up to 100 ohm cm.
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) | 1980-05-16 | 1980-11-15 | 1981-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-05-16 | 1984-11-15 | 1985-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-05-16 | 1988-11-15 | 1989-05-17 | $7700.00 | Window Closed / Lapsed |