US4123286A
Expired / Lapsed
US
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Silicon carbide powder compositions
Assignee: Stemcor Corp
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Filing: 1976-12-27
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Granted: 1978-10-31
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Expires: 1996-12-27
Abstract
Abstract A powder containing substantial amounts of alpha phase silicon carbide suitable for use in subsequent sintering operations to obtain a high-density, high-strength ceramic product is described. The powder may consist substantially entirely of alpha silicon carbide or may consist of mixtures of alpha and beta phase silicon carbide. The silicon carbide powder of the present invention has an average particle size of from about 0.10 to about 2.50 microns and may contain maximum amounts of the following materials by weight based upon 100 parts of powder. }SiO2 2.00 }Free Silicon 0.25 }Iron 0.50 }Alkali and Alkaline Earth } Metals 0.50 }Total Metal Oxides 3.75 } Sinterable powders and methods of producing sintered products from the powders are also described.
Inventors
- 👤 John A. Coppola
- 👤 Harry A. Lawler
- 👤 Carl H. McMurtry
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:32
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
125 words
A silicon carbide powder containing: (a). From about 5 to about 100 percent by weight alpha crystalline phase silicon carbide, (b). said powder containing a maximum of the following components in percent by weight: ______________________________________
SiO.sub.2 2.00
Free Silicon 0.25
Iron 0.50
Alkali and Alkaline
Earth Metals 0.50
Total Metal Oxides 3.75
______________________________________ (c). the particles in said powder having an average particle size from about 0.10 to about 2.50 microns, (d). said powder characterized by the property of being sinterable under substantially pressureless conditions at a temperature between about 1950° C. and about 2500° C. when mixed with between about 0.05 and about 4.0 percent by weight of combinable carbon and from about 0.03 to about 3.0 percent by weight of a densification aid.
Claim 2
Dependent Claim
125 words
A silicon carbide powder containing: (a). From about 5 to about 100 percent by weight alpha crystalline phase silicon carbide, (b). said powder containing a maximum of the following components in percent by weight: ______________________________________
SiO.sub.2 2.00
Free Silicon 0.25
Iron 0.50
Alkali and Alkaline
Earth Metals 0.50
Total Metal Oxides 3.75
______________________________________ (c). the particles in said powder having an average particle size from about 0.10 to about 2.50 microns, (d). said powder characterized by the property of being sinterable under substantially pressureless conditions at a temperature between about 1950° C. and about 2500° C. when mixed with between about 0.05 and about 4.0 percent by weight of combinable carbon and from about 0.03 to about 3.0 percent by weight of a densification aid.
Claim 3
Dependent Claim
22 words
The powder of claim 1 wherein alpha crystalline phase silicon carbide is greater than 50 percent of the total silicon carbide content.
Claim 4
Dependent Claim
17 words
The powder of claim 1 wherein the maximum amount of SiO 2 is 0.5 percent by weight.
Claim 5
Dependent Claim
16 words
The powder of claim 1 wherein the maximum amount of iron is 0.20 percent by weight.
Claim 6
Dependent Claim
14 words
The powder of claim 1 wherein the maximum particle size is about 5.0 microns.
Claim 7
Dependent Claim
22 words
The powder of claim 1 wherein the surface area of the particles is between about 2 and about 50 m 2 /g.
Claim 8
Dependent Claim
18 words
The powder of claim 1 containing between about 0.05 and about 4.0 percent by weight of combinable carbon.
Claim 9
Dependent Claim
15 words
A sinterable silicon carbide powder comprising the powder of claim 7 containing a densification aid.
Claim 10
Dependent Claim
24 words
The powder of claim 8 wherein the densification aid is added in the range of from about 0.03 to about 3.0 percent by weight.
Claim 11
Dependent Claim
23 words
The powder of claim 9 wherein the densification aid is selected from the group consisting of boron, beryllium, their compounds and mixtures thereof.
Claim 12
Dependent Claim
12 words
The powder of claim 9 wherein the densification aid is boron carbide.
Claim 13
Dependent Claim
75 words
A method of making a sintered silicon carbide body comprising the steps of: (a). forming a homogeneous mixture of the powder of claim 8, and (b). shaping said mixture into a green product, and (c). sintering said green product at a temperature of between about 1950 and about 2500° C., and (d). maintaining said temperature for a time sufficient to obtain a silicon carbide ceramic product having a density greater than 75 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) | 1981-10-30 | 1982-05-01 | 1982-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-30 | 1986-05-01 | 1986-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-30 | 1990-05-01 | 1990-10-31 | $7700.00 | Window Closed / Lapsed |