US5308561A
Expired / Lapsed
US
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Process for production of a Si3 N4, based material
Assignee: Bayer AG
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Filing: 1993-04-08
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Granted: 1994-05-03
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Expires: 2013-04-08
Abstract
Abstract High-strength Si 3 N 4 -based material with a narrow range spread of values for mechanical properties useful for producing thick-walled ceramic parts for internal combustion engines, thick-walled ceramic fittings or cutting tools is produced by molding a powder-form starting mixture comprising powdered Si 3 N 4 , finely divided elemental silicon and sintering additives, and subsequently heat treating the mixture to obtain a sintered molding very near the theoretical density of the material.
Inventors
- 👤 Gerhard Leimer
- 👤 Gerhard Wotting
- 👤 Ernst Gugel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 16:19
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/58; C04B35/584; C04B35/593; C04B35/5935; C04B35/591
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
145 words
A process for the production of high-strength Si 3 N 4 -based material with a narrow range spread of values for mechanical properties which comprises: molding a powder-form starting mixture consisting essentially of 5 to 20% by weight finely divided elemental silicon, 1 to 15% by weight of at least one sintering additive and 65-94% by weight powdered Si 3 N 4 , heat treating the starting mixture at a temperature equal to or below 1400° C. in a nitrogen atmosphere at atmospheric pressure until a complete reaction of the elemental silicon with the nitrogen gas to Si 3 N 4 takes place, and continuing the heat treating of the mixture after all of the elemental silicon has been converted to Si 3 N 4 , at a temperature above 1400° C., to obtain a sintered molding very near the theoretical density of the material.
Claim 2
Dependent Claim
145 words
A process for the production of high-strength Si 3 N 4 -based material with a narrow range spread of values for mechanical properties which comprises: molding a powder-form starting mixture consisting essentially of 5 to 20% by weight finely divided elemental silicon, 1 to 15% by weight of at least one sintering additive and 65-94% by weight powdered Si 3 N 4 , heat treating the starting mixture at a temperature equal to or below 1400° C. in a nitrogen atmosphere at atmospheric pressure until a complete reaction of the elemental silicon with the nitrogen gas to Si 3 N 4 takes place, and continuing the heat treating of the mixture after all of the elemental silicon has been converted to Si 3 N 4 , at a temperature above 1400° C., to obtain a sintered molding very near the theoretical density of the material.
Claim 3
Dependent Claim
91 words
A process as claimed in claim 1 wherein the at least one sintering additive consists essentially of at least one material selected from the group consisting of Li 2 O, BeO, MgO, CaO, SrO, BaO, Al 2 O 3 , Sc 2 O 3 , Y 2 O 3 , La 2 O 3 and all other rare earth oxides, TiO 2 , ZrO 2 , HfO 2 , Be 3 N 2 , BN, AlN, ScN, YN, LaN and all other rare earth nitrides, TiN, ZrN, HfN, NbN and TaN.
Claim 4
Dependent Claim
27 words
A process as claimed in claim 1 wherein the sintering additives are those which do not enter into any reaction with the elemental silicon under sintering conditions.
Claim 5
Dependent Claim
93 words
A process as claimed in claim 1 wherein the at least one sintering additive comprises at least one material selected from the group consisting of Li 2 O, BeO, MgO, CaO, SrO, BaO, Al 2 O 3 , Sc 2 O 3 , Y 2 O 3 , La 2 O 3 and all other rare earth oxides, TiO 2 , ZrO 2 , HfO 2 , Be 3 N 2 , BN, AlN, ScN, YN, LaN and all other rare earth nitrides, TiN, ZrN, HfN, NbN TaN, SiC and B 4 C.
Claim 6
Dependent Claim
142 words
A process for the production of high-strength Si 3 N 4 -based material with a narrow range spread of values for mechanical properties which comprises: molding a powder-form starting mixture consisting essentially of 5 to 10% by weight finely divided elemental silicon, 1 to 15% by weight of at least one sintering additive and 75-94% by weight powdered Si 3 N 4 , heat treating the starting mixture at a temperature equal to or below 1400° C. in a nitrogen atmosphere until a complete reaction of the elemental silicon with the nitrogen gas to Si 3 N 4 takes place, and continuing the heat treating of the mixture after all of the elemental silicon has been converted to Si 3 N 4 , at a temperature above 1400° C., to obtain a sintered molding very near the theoretical density of the material.
Claim 7
Dependent Claim
142 words
A process for the production of high-strength Si 3 N 4 -based material with a narrow range spread of values for mechanical properties which comprises: molding a powder-form starting mixture consisting essentially of 5 to 10% by weight finely divided elemental silicon, 1 to 15% by weight of at least one sintering additive and 75-94% by weight powdered Si 3 N 4 , heat treating the starting mixture at a temperature equal to or below 1400° C. in a nitrogen atmosphere until a complete reaction of the elemental silicon with the nitrogen gas to Si 3 N 4 takes place, and continuing the heat treating of the mixture after all of the elemental silicon has been converted to Si 3 N 4 , at a temperature above 1400° C., to obtain a sintered molding very near the theoretical density of the material.
Claim 8
Dependent Claim
91 words
A process as claimed in claim 5 wherein the at least one sintering additive consists essentially of at least one material selected from the group consisting of Li 2 O, BeO, MgO, CaO, SrO, BaO, Al 2 O 3 , Sc 2 O 3 , Y 2 O 3 , La 2 O 3 and all other rare earth oxides, TiO 2 , ZrO 2 , HfO 2 , Be 3 N 2 , BN, AlN, ScN, YN, LaN and all other rare earth nitrides, TiN, ZrN, HfN, NbN and TaN.
Claim 9
Dependent Claim
93 words
A process as claimed in claim 5 wherein the at least one sintering additive comprises at least one material selected from the group consisting of Li 2 O, BeO, MgO, CaO, SrO, BaO, Al 2 O 3 , Sc 2 O 3 , Y 2 O 3 , La 2 O 3 and all other rare earth oxides, TiO 2 , ZrO 2 , HfO 2 , Be 3 N 2 , BN, AlN, ScN, YN, LaN and all other rare earth nitrides, TiN, ZrN, HfN, NbN TaN, SiC and B 4 C.
Claim 10
Dependent Claim
29 words
A process as claimed in claim 5 wherein the heat treatment is carried out by sintering under elevated nitrogen pressure by hot isostatic pressing or by axial hot pressing.
Claim 11
Dependent Claim
23 words
A process as claimed in claim 5 wherein the heat treatment is carried out by hot isostatic pressing or by axial hot pressing.
Claim 12
Dependent Claim
17 words
A process as claimed in claim 9 wherein the heat treatment is carried out under nitrogen pressure.
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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) | 1997-05-02 | 1997-11-01 | 1998-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-02 | 2001-11-01 | 2002-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-02 | 2005-11-01 | 2006-05-03 | $7700.00 | Window Closed / Lapsed |