US4702901A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for growing silicon carbide whiskers by undercooling
Assignee: United States Department of Energy
•
Filing: 1986-03-12
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Granted: 1987-10-27
•
Expires: 2006-03-12
Abstract
Abstract A method of growing silicon carbide whiskers, especially in the β form, using a heating schedule wherein the temperature of the atmosphere in the growth zone of a furnace is first heated to or beyond the growth temperature and then is cooled to or below the growth temperature to induce nucleation of whiskers at catalyst sites at a desired point in time which results in the selection.
Inventors
- 👤 Peter D. Shalek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:14
CPC Classifications
C; C30; C30B; C30B25/00; C30B25/005; C30B29/00; C30B29/10; C30B29/36
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
80 words
A method of manufacturing β silicon carbide whiskers which comprises heating a reaction system consisting of a silicon source, a carbon source, and a catalyst in a reducing atmosphere whereby said reaction system is first heated beyond the whisker growth temperature and then said reaction system is cooled to a temperature to or below the growth temperature to induce nucleation at catalyst sites at a desired point in time, before being held at the growth temperature for the growth period.
Claim 2
Independent Claim
80 words
A method of manufacturing β silicon carbide whiskers which comprises heating a reaction system consisting of a silicon source, a carbon source, and a catalyst in a reducing atmosphere whereby said reaction system is first heated beyond the whisker growth temperature and then said reaction system is cooled to a temperature to or below the growth temperature to induce nucleation at catalyst sites at a desired point in time, before being held at the growth temperature for the growth period.
Claim 3
Dependent Claim
15 words
The method of claim 1 wherein said growth temperature is from 1350° to 1500° C.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein said reducing atmosphere is a hydrogen atmosphere.
Claim 5
Dependent Claim
16 words
The method of claim 1 wherein said carbon source before whisker growth includes a graphite substrate.
Claim 6
Dependent Claim
17 words
The method of claim 1 wherein said silicon source is a SiO 2 and carbon powder mixture.
Claim 7
Dependent Claim
23 words
The method of claim 1 wherein said catalyst comprises one or more of the following metals: manganese, cobalt, nickel, iron, chromium, and silicon.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein said reaction system is cooled 150° C. below the growth temperature, before the growth period.
Claim 9
Dependent Claim
23 words
The method of claim 1 wherein said reaction system is heated up to 100° C. beyond the growth temperature before the growth period.
Claim 10
Dependent Claim
17 words
The method of claim 1 wherein said β silicon carbide whiskers are grown by the vapor-liquid-solid mechanism.
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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) | 1990-10-26 | 1991-04-27 | 1991-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-26 | 1995-04-27 | 1995-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-26 | 1999-04-27 | 1999-10-27 | $7700.00 | Window Closed / Lapsed |