US4113830A
Expired / Lapsed
US
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Method of fabricating silicon nitride bodies
Assignee: United States Department of the Air Force
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Filing: 1974-03-18
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Granted: 1978-09-12
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Expires: 1994-03-18
Abstract
Abstract In a method for fabricating highly dense, polycrystalline silicon nitride bodies, a mixture of silicon nitride powder and an oxide, hydride or nitride of an element of the lanthanide series in powder form is hot pressed at a temperature ranging from 1600° to 1750° C for a period of 30 to 60 minutes. The method is particularly useful for fabricating structural components, such as stators, blades, airfoils and buckets in high performance gas turbine engines.
Inventors
- 👤 Khodabakhsh S. Mazdiyasni
- 👤 Charles M. Cooke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:57
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
153 words
A method for fabricating a silicon nitride body which comprises compressing under a vacuum or in an inert atmosphere a mixture of (1) a silicon compound selected from the group consisting of alpha silicon nitride, amorphous silicon nitride and polymeric silicon diimide powders and (2) 0.5 to 10 weight percent, based on the weight of the silicon compound, of a sintering aid in finely divided form selected from the group consisting of compounds having the formulas M 2 O 3 , MH 3 and MN, where M is an element of the lanthanide series at a pressure ranging from about 4000 to 6000 psi and at a temperature ranging from 1600° to 1750° C. in a compression zone formed of graphite and lined with a sheet of graphite; and continuing the compression step until there is obtained a silicon nitride body having a density substantially equal to the theoretical density of silicon nitride.
Claim 2
Independent Claim
153 words
A method for fabricating a silicon nitride body which comprises compressing under a vacuum or in an inert atmosphere a mixture of (1) a silicon compound selected from the group consisting of alpha silicon nitride, amorphous silicon nitride and polymeric silicon diimide powders and (2) 0.5 to 10 weight percent, based on the weight of the silicon compound, of a sintering aid in finely divided form selected from the group consisting of compounds having the formulas M 2 O 3 , MH 3 and MN, where M is an element of the lanthanide series at a pressure ranging from about 4000 to 6000 psi and at a temperature ranging from 1600° to 1750° C. in a compression zone formed of graphite and lined with a sheet of graphite; and continuing the compression step until there is obtained a silicon nitride body having a density substantially equal to the theoretical density of silicon nitride.
Claim 3
Dependent Claim
21 words
The method according to claim 1 in the mixture is compressed under a vacuum of 10 -6 to 10 -3 torr.
Claim 4
Dependent Claim
19 words
The method according to claim 1 in which the mixture is compressed under a blanket of an inert atmosphere.
Claim 5
Dependent Claim
21 words
The method according to claim 1 in which the sintering aid is Ce 2 O 3 , CeH 3 or CeN.
Claim 6
Dependent Claim
17 words
The method according to claim 1 in which the sintering aid is La 2 O 3 .
Claim 7
Dependent Claim
17 words
The method according to claim 1 in which the sintering aid is Yb 2 O 3 .
Claim 8
Dependent Claim
17 words
The method according to claim 1 in which the sintering aid is Gd 2 O 3 .
Claim 9
Dependent Claim
17 words
The method according to claim 1 in which the sintering aid is Dy 2 O 3 .
Claim 10
Dependent Claim
15 words
The method according to claim 1 in which the silicon compound is polymeric silicon diimide.
Claim 11
Independent Claim
133 words
A method for fabricating a silicon nitride body which comprises compressing under a vacuum of 10 -6 to 10 -3 torr a mixture of (1) a silicon compound selected from the group consisting of alpha silicon nitride, amorphous silicon nitride and polymeric silicon diimide powders and (2) 0.5 to 10 weight percent of submicron size Ce 2 O 3 , based on the weight of the silicon compound, at a pressure ranging from about 4000 to 6000 psi and at a temperature ranging from 1600° to 1750° C. in a compression zone formed of graphite and lined with a sheet of graphite; and continuing the compression step until a silicon nitride body is obtained which is substantially free of cerium and has a density substantially equal to the theoretical density of silicon nitride.
Claim 12
Independent Claim
133 words
A method for fabricating a silicon nitride body which comprises compressing under a vacuum of 10 -6 to 10 -3 torr a mixture of (1) a silicon compound selected from the group consisting of alpha silicon nitride, amorphous silicon nitride and polymeric silicon diimide powders and (2) 0.5 to 10 weight percent of submicron size Ce 2 O 3 , based on the weight of the silicon compound, at a pressure ranging from about 4000 to 6000 psi and at a temperature ranging from 1600° to 1750° C. in a compression zone formed of graphite and lined with a sheet of graphite; and continuing the compression step until a silicon nitride body is obtained which is substantially free of cerium and has a density substantially equal to the theoretical density of silicon nitride.
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) | 1981-09-11 | 1982-03-13 | 1982-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-11 | 1986-03-13 | 1986-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-11 | 1990-03-13 | 1990-09-12 | $7700.00 | Window Closed / Lapsed |