US4879080A
Expired / Lapsed
US
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High density silicon nitride bodies
Assignee: Osram Sylvania Inc
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Filing: 1984-05-02
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Granted: 1989-11-07
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Expires: 2004-05-02
Abstract
Abstract A pressureless sintering process is disclosed for producing silicon nitride bodies of near theoretical density from an admixture of silicon nitride and sintering aids of mixtures of lanthanum oxide and aluminum oxide, lanthanum aluminate, and mixtures of lanthanum aluminate and aluminum oxide and mixtures of lanthanum aluminate and lanthanum oxide.
Inventors
- 👤 Martin Y. Hsieh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:30
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B2235/00; C04B2235/02; C04B2235/30; C04B2235/32; C04B2235/3217; C04B2235/3222; C04B2235/3224; C04B2235/3227; C04B2235/60; C04B2235/608; C04B2235/70; C04B2235/72; C04B2235/74; C04B2235/77
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
90 words
A process for producing silicon nitride bodies of near theoretical density said process comprising: (a) forming an admixture consisting essentially of silicon nitride and sintering aids selected from the group consisting of lanthanum aluminate, mixtures of lanthanum aluminate and aluminum oxide and mixtures of lanthanum aluminate and lanthanum oxide, and a volatile binder, (b) pressing said admixture to form a green silicon nitride body and, (c) sintering said green silicon nitride body to produce a silicon nitride body having a density of greater than about 96% of the theoretical density.
Claim 2
Dependent Claim
90 words
A process for producing silicon nitride bodies of near theoretical density said process comprising: (a) forming an admixture consisting essentially of silicon nitride and sintering aids selected from the group consisting of lanthanum aluminate, mixtures of lanthanum aluminate and aluminum oxide and mixtures of lanthanum aluminate and lanthanum oxide, and a volatile binder, (b) pressing said admixture to form a green silicon nitride body and, (c) sintering said green silicon nitride body to produce a silicon nitride body having a density of greater than about 96% of the theoretical density.
Claim 3
Dependent Claim
42 words
A process according to claim 1 wherein the silicon nitride body has a composition consisting essentially of by weight: from about 1.5% to about 30% of lanthanum oxide, and about 0.5% to about 12.0% of aluminum oxide and the balance silicon nitride.
Claim 4
Dependent Claim
27 words
A process.according to claim 1 wherein the sintering aid is a mixture of lanthanum oxide and lanthanum aluminate in a weight ratio of about 1 to 1.
Claim 5
Dependent Claim
13 words
A process according to claim 1 wherein the sintering aid is lanthahum aluminate.
Claim 6
Dependent Claim
19 words
A process according to claim 1 wherein the sintering temperature is from about 1225° C. to about 1800° C.
Claim 7
Dependent Claim
26 words
A process according to claim 1 wherein the density of the sintered silicon nitride body is from about 97% to about 100% of the theoretical density.
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) | 1992-11-06 | 1993-05-08 | 1993-11-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-11-06 | 1997-05-08 | 1997-11-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-11-06 | 2001-05-08 | 2001-11-07 | $7700.00 | Window Closed / Lapsed |