US4073845A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High density high strength S13 N4 ceramics prepared by pressureless sintering of partly crystalline, partly amorphous S13 N4 powder
Assignee: GTE Sylvania Inc
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Filing: 1976-01-29
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Granted: 1978-02-14
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Expires: 1996-01-29
Abstract
Abstract Si 3 N 4 ceramics exhibiting densities and modulus of rupture values heretofore obtainable only by hot pressing are produced by pressureless sintering of powder compacts of partly amorphours, partly crystalline Si 3 N 4 powder containing between 5 and 60 percent by weight of crystalline material.
Inventors
- 👤 Sergej T. Buljan
- 👤 Philip E. Stermer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:10
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
51 words
A powder mixture consisting essentially of Si 3 N 4 powder of average particle size below about 3 microns characterized in that the Si 3 N 4 powder consists of from about 5 to 60 weight percent crystalline Si 3 N 4 , remainder substantially amorphous Si 3 N 4 .
Claim 2
Dependent Claim
51 words
A powder mixture consisting essentially of Si 3 N 4 powder of average particle size below about 3 microns characterized in that the Si 3 N 4 powder consists of from about 5 to 60 weight percent crystalline Si 3 N 4 , remainder substantially amorphous Si 3 N 4 .
Claim 3
Dependent Claim
36 words
The powder mixture of claim 1 in which the Si 3 N 4 powder consists of from 10 to 30 weight percent crystalline Si 3 N 4 , remainder substantially amorphous Si 3 N 4 .
Claim 4
Dependent Claim
20 words
The powder mixture of claim 2 in which the Si 3 N 4 powder consists of partially crystallized amorphous particles.
Claim 5
Dependent Claim
26 words
The powder mixture of claim 2 in which the Si 3 N 4 powder consists of a mixture of substantially crystallized particles and substantially amorphous particles.
Claim 6
Dependent Claim
42 words
The powder mixture of claim 4 additionally containing up to 5 weight percent of a grain growth inhibiting additive selected from the group consisting of MgO, CrN, Y 2 O 3 , ZrO 2 , ZrN, and La 2 O 3 .
Claim 7
Dependent Claim
20 words
A powder compact of the powder of claim 1 and a volatile binder to provide green strength to the compact.
Claim 8
Dependent Claim
21 words
A powder compact of the powder mixture of claim 1 and a volatile binder to provide green strength to the compact.
Claim 9
Dependent Claim
21 words
A powder compact of the powder mixture of claim 3 and a volatile binder to provide green strength to the compact.
Claim 10
Dependent Claim
21 words
A powder compact of the powder mixture of claim 4 and a volatile binder to provide green strength to the compact.
Claim 11
Dependent Claim
21 words
A powder compact of the powder mixture of claim 5 and a volatile binder to provide green strength to the compact.
Claim 12
Independent Claim
136 words
A method of producing a ceramic body, the method comprising: (a) mixing starting materials consisting essentially of Si 3 N 4 powder of average particle size below about 3 microns, the powder consisting of from about 5 to 60 weight percent crystalline Si 3 N 4 , remainder amorphous Si 3 N 4 , (b) consolidating the powder with a volatile binder to produce a powder compact having adequate green strength and density, and (c) sintering the compact in a non-reactive atmosphere without pressure at a temperature of from about 1400° to 1700° C for at least about one hour to achieve a dense Si 3 N 4 ceramic body having a density of at least 90 and up to 96 percent of theoretical density and a room temperature modulus of rupture value approaching 100,000 psi.
Claim 13
Independent Claim
136 words
A method of producing a ceramic body, the method comprising: (a) mixing starting materials consisting essentially of Si 3 N 4 powder of average particle size below about 3 microns, the powder consisting of from about 5 to 60 weight percent crystalline Si 3 N 4 , remainder amorphous Si 3 N 4 , (b) consolidating the powder with a volatile binder to produce a powder compact having adequate green strength and density, and (c) sintering the compact in a non-reactive atmosphere without pressure at a temperature of from about 1400° to 1700° C for at least about one hour to achieve a dense Si 3 N 4 ceramic body having a density of at least 90 and up to 96 percent of theoretical density and a room temperature modulus of rupture value approaching 100,000 psi.
Claim 14
Dependent Claim
36 words
The method of claim 11 in which the Si 3 N 4 powder consists of from about 10 to 30 percent by weight crystalline Si 3 N 4 , remainder amorphous Si 3 N 4 .
Claim 15
Dependent Claim
19 words
The method of claim 11 in which the Si 3 N 4 powder consists of partially crystallized amorphous particles.
Claim 16
Dependent Claim
25 words
The method of claim 11 in which the Si 3 N 4 powder consists of a mixture of substantially crystalline particles and substantially amorphous particles.
Claim 17
Dependent Claim
44 words
The method of claim 11 in which the starting materials additionally contain up to 20 weight percent of a sintering additive selected from the group consisting of MgO, CrN, Y 2 O 3 , ZrO 2 , ZrN, and La 2 O 3 .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-13 | 1981-08-15 | 1982-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-13 | 1985-08-15 | 1986-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-13 | 1989-08-15 | 1990-02-14 | $7700.00 | Window Closed / Lapsed |