US4871697A
Expired / Lapsed
US
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Method of producing homogeneous silicon nitride sintered bodies
Assignee: NGK Insulators Ltd
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Filing: 1988-01-07
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Granted: 1989-10-03
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Expires: 2008-01-07
Abstract
Abstract A homogeneous silicon nitride sintered body produced by placing a shaped body of silicon nitride powder into a high density silicon carbide sagger having particular properties and then firing under particular conditions.
Inventors
- 👤 Issei Hayakawa
- 👤 Noriyuki Ukai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:21
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/622; C04B35/64
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
69 words
A method of producing a homogeneous silicon nitride sintered body, comprising: placing a shaped body consisting essentially of silicon nitride powder and sintering aid into a high density silicon carbide sagger having a bulk specific gravity of at least about 3.0 and an apparent porosity of not greater than about 1.0%; and firing the shaped body in a temperature range of about 1,500°-1,800° C. and at about atmospheric pressure.
Claim 2
Independent Claim
69 words
A method of producing a homogeneous silicon nitride sintered body, comprising: placing a shaped body consisting essentially of silicon nitride powder and sintering aid into a high density silicon carbide sagger having a bulk specific gravity of at least about 3.0 and an apparent porosity of not greater than about 1.0%; and firing the shaped body in a temperature range of about 1,500°-1,800° C. and at about atmospheric pressure.
Claim 3
Dependent Claim
16 words
A method according to claim 1, wherein the sagger has a thickness of about 5-30 mm.
Claim 4
Dependent Claim
26 words
A method according to claim 1, wherein the shaped body is fired at a gauge pressure of about not greater than about 0.5 Kg/cm 2 .
Claim 5
Independent Claim
78 words
A method of producing a homogeneous silicon nitride sintered body, comprising: placing a shaped body consiting essentially of silicon nitride powder and sintering aid into a high density silicon carbide sagger having a bulk specific gravity of at least about 3.0 and an apparent porosity of not greater than about 1.0%; and firing the shaped body in a temperature range of about 1,500°-2,000° C. and at a gauge pressure of not greater than about 10 Kg/cm 2 .
Claim 6
Independent Claim
78 words
A method of producing a homogeneous silicon nitride sintered body, comprising: placing a shaped body consiting essentially of silicon nitride powder and sintering aid into a high density silicon carbide sagger having a bulk specific gravity of at least about 3.0 and an apparent porosity of not greater than about 1.0%; and firing the shaped body in a temperature range of about 1,500°-2,000° C. and at a gauge pressure of not greater than about 10 Kg/cm 2 .
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) | 1992-10-02 | 1993-04-03 | 1993-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-02 | 1997-04-03 | 1997-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-02 | 2001-04-03 | 2001-10-03 | $7700.00 | Window Closed / Lapsed |