US3962406A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of manufacturing silicon carbide crystals
Assignee: US Philips Corp
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Filing: 1972-08-15
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Granted: 1976-06-08
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Expires: 1992-08-15
Abstract
Abstract A method of manufacturing silicon carbide crystals in which a core of silicon dioxide is embedded in a mass of granular silicon carbide, or materials which form silicon carbide on heating this mass being heated to a temperature at which silicon dioxide volatilizes, i.e. above about 1500°C, and the silicon carbide coheres. This leaves a cavity, formerly occupied by the silicon dioxide which is surrounded by silicon carbide. Heating is then continued at a temperature, above about 2500°C, at which silicon carbide crystals are formed on the walls of the cavity.
Inventors
- 👤 Wilhelmus Franciscus Knippenberg
- 👤 Gerrit Verspui
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:45
CPC Classifications
C; C30; C30B; C30B29/00; C30B29/10; C30B29/36; B; B66; B66C; B66C23/00; B66C23/62; B66F; B66F3/00; B66F3/22; C01; C01B; C01B32/00; C01B32/90; C01B32/914; C01B32/956; C01B32/963; C01B32/97; C01B32/991; C01P; C01P2002/00; C01P2002/50; C01P2002/52; C01P2002/54; C01P2004/00; C01P2004/20; C01P2006/00; C01P2006/12; Y; Y10; Y10S; Y10S148/00; Y10S148/073; Y10S148/148
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
122 words
A method of forming silicon carbide crystals on a wall of silicon carbide, comprising the steps of: positioning within a mass of loose granular material comprising silicon carbide or the constituents thereof a core consisting essentially of silicon dioxide, said core preventing said loose granular material from entering an intended cavity defined and occupied by said core; gradually raising the temperature of said mass and core until a coherent wall of silicon carbide forms around said core and said core volatilizes leaving said intended cavity bounded by a coherent wall of silicon carbide; and maintaining the temperature of said cavity and coherent wall within the range of 2000°C to 2600°C until silicon carbide crystals form within said cavity on said coherent wall.
Claim 2
Independent Claim
122 words
A method of forming silicon carbide crystals on a wall of silicon carbide, comprising the steps of: positioning within a mass of loose granular material comprising silicon carbide or the constituents thereof a core consisting essentially of silicon dioxide, said core preventing said loose granular material from entering an intended cavity defined and occupied by said core; gradually raising the temperature of said mass and core until a coherent wall of silicon carbide forms around said core and said core volatilizes leaving said intended cavity bounded by a coherent wall of silicon carbide; and maintaining the temperature of said cavity and coherent wall within the range of 2000°C to 2600°C until silicon carbide crystals form within said cavity on said coherent wall.
Claim 3
Dependent Claim
21 words
A method as defined in claim 1 wherein the temperature of said cavity and coherent wall is maintained at approximately 2500°C.
Claim 4
Dependent Claim
26 words
A method as defined in claim 1 wherein said core or loose granular material also contains lanthanum oxide to promote formation of whisker-like silicon carbide crystals.
Claim 5
Dependent Claim
29 words
A method as defined in claim 1 wherein said loose granular material comprises a mixture of coke, sand, sawdust and common salt and said core consists essentially of sand.
Claim 6
Dependent Claim
25 words
A method as defined in claim 1 wherein said core is a combustible mould substantially filled with a granular material consisting essentially of silicon dioxide.
Claim 7
Dependent Claim
14 words
A method as defined in claim 1 wherein said core consists esentially of glass.
Claim 8
Dependent Claim
13 words
A method as defined in claim 6 wherein said glass core is hollow.
Claim 9
Dependent Claim
29 words
A method as defined in claim 6 wherein said glass core is composed of borate glass, thereby forming boron-doped silicon carbide crystals on said coherent wall of said cavity.
References Cited (Backward Citations)
US2854364A
Cited
US3275415A
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US3460987A
Cited
JPS4318829Y1
Cited
FR1536842A
Cited
DE1810504A1
Cited
US3647384A
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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) | 1979-06-08 | 1979-12-08 | 1980-06-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-06-08 | 1983-12-08 | 1984-06-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-06-08 | 1987-12-08 | 1988-06-08 | $7700.00 | Window Closed / Lapsed |