US4295890A
Expired / Lapsed
US
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Submicron beta silicon carbide powder and sintered articles of high density prepared therefrom
Assignee: PPG Industries Inc
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Filing: 1977-10-31
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Granted: 1981-10-20
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Expires: 1997-10-31
Abstract
Abstract Shaped silicon carbide ceramic articles of high density, e.g., at least 90 percent of theoretical, are produced by cold pressing and sintering boron-containing high purity, submicron beta silicon carbide powder. The silicon carbide powder is produced preferably by gas phase reaction of silicon halide, e.g., silicon tetrachloride, carbon source reactant, e.g., halogenated hydrocarbon, and boron source reactant, e.g., boron trichloride, with a hydrogen plasma.
Inventors
- 👤 Frederick G. Stroke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 00:40
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565; C01; C01B; C01B32/00; C01B32/90; C01B32/914; C01B32/956; C01B32/991; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2004/00; C01P2004/10; C01P2004/12; C01P2006/00; C01P2006/10; C01P2006/12; C01P2006/80
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
95 words
A substantially pure submicron boron-containing beta silicon carbide powder composition consisting essentially of silicon carbide powder substantially all of the beta crystalline form, said powder having a surface area of between about 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed homogeneously distributed boron-containing additive in an amount equivalent to between 0.15 and 0.25 weight percent boron, based on the silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on the silicon carbide.
Claim 2
Dependent Claim
95 words
A substantially pure submicron boron-containing beta silicon carbide powder composition consisting essentially of silicon carbide powder substantially all of the beta crystalline form, said powder having a surface area of between about 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed homogeneously distributed boron-containing additive in an amount equivalent to between 0.15 and 0.25 weight percent boron, based on the silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on the silicon carbide.
Claim 3
Dependent Claim
23 words
The powder composition of claim 1 wherein the silicon carbide powder surface area is between about 4 and 12 square meters per gram.
Claim 4
Dependent Claim
23 words
The powder composition of claim 1 wherein the number mean particle size of the silicon carbide particles is between 0.15 and 0.4 microns.
Claim 5
Dependent Claim
23 words
The powder composition of claim 1 wherein the boron-containing additive is boron carbide, elemental boron or mixtures of boron carbide and elemental boron.
Claim 6
Dependent Claim
21 words
The powder composition of claim 1 or 4 wherein the silicon carbide powder contains less than 0.1 weight percent metal impurities.
Claim 7
Dependent Claim
123 words
A silicon carbide powder composition capable of being pressure-less sintered to articles having a density of at least 85 percent of the theoretical density of silicon carbide, which composition consists essentially of substantially pure, submicron boron-containing beta silicon carbide powder, said powder having from traces to less than 1 weight percent alpha silicon carbide, and a surface area of between about 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed homogeneously distributed, boron-containing additive in an amount equivalent to between 0.15 and 0.25 weight percent boron, based on the silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide.
Claim 8
Dependent Claim
123 words
A silicon carbide powder composition capable of being pressure-less sintered to articles having a density of at least 85 percent of the theoretical density of silicon carbide, which composition consists essentially of substantially pure, submicron boron-containing beta silicon carbide powder, said powder having from traces to less than 1 weight percent alpha silicon carbide, and a surface area of between about 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed homogeneously distributed, boron-containing additive in an amount equivalent to between 0.15 and 0.25 weight percent boron, based on the silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide.
Claim 9
Dependent Claim
23 words
The powder composition of claim 6 wherein the silicon carbide powder surface area is between about 4 and 12 square meters per gram.
Claim 10
Dependent Claim
23 words
The powder composition of claim 6 wherein the boron-containing additive is boron carbide, elemental boron or mixtures of boron carbide and elemental boron.
Claim 11
Dependent Claim
21 words
The powder composition of claim 6 or 8 wherein the silicon carbide powder contains less than 0.1 weight percent metal impurities.
Claim 12
Dependent Claim
124 words
A silicon carbide powder composition consisting essentially of a blend of from about 30 to 90 weight percent substantially pure, submicron beta silicon carbide containing coformed, homogeneously distributed, boron-containing additive, and from 70 to 10 weight percent substantially pure, substantially boron-free submicron beta silicon carbide, each of said beta silicon carbide powders having from traces to less than 1 weight percent alpha silicon carbide, and a surface area of between about 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, said powder blend containing from about 0.15 to about 0.25 weight percent boron and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide.
Claim 13
Dependent Claim
124 words
A silicon carbide powder composition consisting essentially of a blend of from about 30 to 90 weight percent substantially pure, submicron beta silicon carbide containing coformed, homogeneously distributed, boron-containing additive, and from 70 to 10 weight percent substantially pure, substantially boron-free submicron beta silicon carbide, each of said beta silicon carbide powders having from traces to less than 1 weight percent alpha silicon carbide, and a surface area of between about 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, said powder blend containing from about 0.15 to about 0.25 weight percent boron and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide.
Claim 14
Dependent Claim
57 words
The silicon carbide powder composition of claim 10 wherein the composition consists essentially of from 45 to 85 weight percent of the boron-containing silicon carbide powder and from 55 to 15 weight percent of the substantially boron-free silicon carbide powder and the boron-containing additive is boron carbide, elemental boron or mixtures of boron carbide and elemental boron.
Claim 15
Dependent Claim
93 words
A substantially pure submicron boron-containing beta silicon carbide powder composition consisting essentially of silicon carbide powder substantially all of the beta crystalline form, said powder having a surface area of between about 3 and about 15 square meters per gram, the number means particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed, homogeneously distributed, boron-containing additive in an amount equivalent to about 0.27 weight percent boron, based on the silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on the silicon carbide.
Claim 16
Dependent Claim
93 words
A substantially pure submicron boron-containing beta silicon carbide powder composition consisting essentially of silicon carbide powder substantially all of the beta crystalline form, said powder having a surface area of between about 3 and about 15 square meters per gram, the number means particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed, homogeneously distributed, boron-containing additive in an amount equivalent to about 0.27 weight percent boron, based on the silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on the silicon carbide.
Claim 17
Dependent Claim
121 words
A silicon carbide powder composition capable of being pressureless sintered to articles having a density of at least 85 percent of the theoretical density of silicon carbide, which composition consists essentially of substantially pure, submicron boron-containing beta silicon carbide powder, said powder having from traces to less than 1 weight percent alpha silicon carbide, and a surface area of between about 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed, homogeneously distributed, boron-containing additive in an amount equivalent to about 0.27 weight percent boron, based on the silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide.
Claim 18
Dependent Claim
121 words
A silicon carbide powder composition capable of being pressureless sintered to articles having a density of at least 85 percent of the theoretical density of silicon carbide, which composition consists essentially of substantially pure, submicron boron-containing beta silicon carbide powder, said powder having from traces to less than 1 weight percent alpha silicon carbide, and a surface area of between about 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed, homogeneously distributed, boron-containing additive in an amount equivalent to about 0.27 weight percent boron, based on the silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide.
Claim 19
Dependent Claim
25 words
The powder composition of claims 12 or 13 wherein the boron-containing additive is boron carbide, elemental boron or mixtures of boron carbide and elemental boron.
Claim 20
Dependent Claim
19 words
The powder composition of claim 14 wherein the silicon carbide powder contains less than 0.1 weight percent metal impurities.
Claim 21
Dependent Claim
47 words
A shaped sintered silicon carbide article consisting essentially of silicon carbide, from about 0.15 to 0.25 weight percent boron and from about 0.05 to about 1.5 weight percent free carbon, said article having a density of at least 85 percent of the theoretical density of silicon carbide.
Claim 22
Dependent Claim
47 words
A shaped sintered silicon carbide article consisting essentially of silicon carbide, from about 0.15 to 0.25 weight percent boron and from about 0.05 to about 1.5 weight percent free carbon, said article having a density of at least 85 percent of the theoretical density of silicon carbide.
Claim 23
Dependent Claim
44 words
A shaped sintered silicon carbide article consisting essentially of silicon carbide, about 0.27 weight percent boron and from about 0.05 to about 1.5 weight percent free carbon, said article having a density of at least 90 percent of the theoretical density of silicon carbide.
Claim 24
Dependent Claim
44 words
A shaped sintered silicon carbide article consisting essentially of silicon carbide, about 0.27 weight percent boron and from about 0.05 to about 1.5 weight percent free carbon, said article having a density of at least 90 percent of the theoretical density of silicon carbide.
Claim 25
Dependent Claim
25 words
The shaped sintered silicon carbide article of claims 16 or 17 wherein the beta crystalline form is the dominant crystal form in the sintered article.
Claim 26
Dependent Claim
24 words
The shaped sintered silicon carbide article of claims 16 or 17 wherein the microstructure of the article is fine and of relatively uniform size.
Claim 27
Dependent Claim
24 words
The shaped sintered silicon carbide article of claims 16 or 17 wherein the article has a density of at least 95 percent of theoretical.
Claim 28
Independent Claim
149 words
A method for preparing a shaped sintered silicon carbide article, which comprises cold pressing into a desired shape a boron-containing silicon carbide composition consisting essentially of substantially pure, submicron beta silicon carbide powder, said powder having from traces to less than 1 weight percent alpha silicon carbide, a surface area of between 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed, homogeneously distributed, boron-containing additive in an amount equivalent to between 0.15 and 0.25 weight percent boron, based on silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide, and sintering such article at temperatures of between about 1850° C. and 2150° C. in an inert atmosphere until the article has a density of at least 85 percent of the theoretical density for silicon carbide.
Claim 29
Independent Claim
149 words
A method for preparing a shaped sintered silicon carbide article, which comprises cold pressing into a desired shape a boron-containing silicon carbide composition consisting essentially of substantially pure, submicron beta silicon carbide powder, said powder having from traces to less than 1 weight percent alpha silicon carbide, a surface area of between 3 and about 15 square meters per gram, the number mean particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed, homogeneously distributed, boron-containing additive in an amount equivalent to between 0.15 and 0.25 weight percent boron, based on silicon carbide, and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide, and sintering such article at temperatures of between about 1850° C. and 2150° C. in an inert atmosphere until the article has a density of at least 85 percent of the theoretical density for silicon carbide.
Claim 30
Independent Claim
147 words
A method for preparing a shaped sintered silicon carbide article, which comprises cold pressing into a desired shape a boron-containing silicon carbide composition consisting essentially of substantially pure, submicron beta silicon carbide powder, said powder having from traces to less than 1 weight percent alpha silicon carbide, a surface area of between 3 and about 15 square meters per gram, the number means particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed, homogeneously distributed, boron-containing additive in an amount equivalent to about 0.27 weight percent boron, based on silicon carbide and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide, and sintering such article at temperatures of between about 1850° C. and 2150° C. in an inert atmosphere until the article has a density of at least 85 percent of the theoretical density for silicon carbide.
Claim 31
Independent Claim
147 words
A method for preparing a shaped sintered silicon carbide article, which comprises cold pressing into a desired shape a boron-containing silicon carbide composition consisting essentially of substantially pure, submicron beta silicon carbide powder, said powder having from traces to less than 1 weight percent alpha silicon carbide, a surface area of between 3 and about 15 square meters per gram, the number means particle size of the silicon carbide particles comprising the powder being between 0.08 and 0.8 microns, coformed, homogeneously distributed, boron-containing additive in an amount equivalent to about 0.27 weight percent boron, based on silicon carbide and between 0.05 and 1.5 weight percent free carbon, based on silicon carbide, and sintering such article at temperatures of between about 1850° C. and 2150° C. in an inert atmosphere until the article has a density of at least 85 percent of the theoretical density for silicon carbide.
Claim 32
Independent Claim
25 words
A method according to claims 21 or 22 wherein the boron-containing additive is boron carbide, elemental boron or mixtures of boron carbide and elemental boron.
Claim 33
Dependent Claim
19 words
A method according to claim 23 wherein the silicon carbide powder contains less than 0.1 weight percent metal impurities.
Claim 34
Dependent Claim
20 words
A method according to claim 23 wherein the sintered article has a density of at least 95 percent of theoretical.
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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) | 1984-10-19 | 1985-04-20 | 1985-10-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-19 | 1989-04-20 | 1989-10-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-19 | 1993-04-20 | 1993-10-20 | $7700.00 | Window Closed / Lapsed |