US5071600A
Expired / Lapsed
US
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Preparation of substantially crystalline silicon carbide fibers from polycarbosilane
Assignee: COI Ceramics Inc
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Filing: 1990-01-16
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Granted: 1991-12-10
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Expires: 2010-01-16
Abstract
Abstract This invention relates to the preparation of thermally stable, substantially polycrystalline silicon carbide ceramic fibers derived from a polycarbosilane resin. The unexpected thermal stability of these fibers is achieved by the incorporation of boron prior to ceramification.
Inventors
- 👤 David C. Deleeuw
- 👤 Jonathan Lipowitz
- 👤 Paul P. Lu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 17:10
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/515; C04B35/56; C04B35/565; C04B35/571
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
54 words
A process for the preparation of thermally stable, substantially polycrystalline silicon carbide fibers comprising: forming fibers from a preceramic polymer comprising a polycarbosilane resin having at least about 0.2% by weight boron incorporated therein: infusibilizing said fibers; and pyrolyzing said fibers at a temperature of greater than about 1600° C. in a nonoxidizing environment.
Claim 2
Dependent Claim
54 words
A process for the preparation of thermally stable, substantially polycrystalline silicon carbide fibers comprising: forming fibers from a preceramic polymer comprising a polycarbosilane resin having at least about 0.2% by weight boron incorporated therein: infusibilizing said fibers; and pyrolyzing said fibers at a temperature of greater than about 1600° C. in a nonoxidizing environment.
Claim 3
Dependent Claim
28 words
The process of claim 1 in which said substantially polycrystalline silicon carbide fibers have at least about 75% crystallinity and a density of at least about 2.9 g/cc.
Claim 4
Dependent Claim
28 words
The process of claim 2 in which said fibers are formed by a spinning method selected from the group consisting of melt spinning, wet spinning and dry spinning.
Claim 5
Dependent Claim
18 words
The process of claim 1 in which said polycarbosilane comprises a polymer with repeating (--SiHCH 3 --CH2--) units.
Claim 6
Dependent Claim
36 words
The process of claim 3 in which said fibers are infusibilized by a method selected from the group consisting of air treatment, exposure to gamma irradiation, exposure to UV light and exposure to an oxidizing agent.
Claim 7
Dependent Claim
36 words
The process of claim 5 in which the fibers are pyrolyzed to a temperature of about 1800° C. for about 1 hour in an atmosphere selected from the group consisting of argon, helium and mixtures thereof.
Claim 8
Dependent Claim
60 words
A process for the preparation of thermally stable, substantially polycrystalline silicon carbide fibers comprising: forming fibers from a preceramic polymer comprising a polycarbosilane resin; infusibilizing said fibers; and pyrolyzing said fibers at a temperature of greater than about 1600° C. in a non-oxidizing environment wherein at least about 0.2% by weight boron is incorporated during said infusibilization or said pyrolysis.
Claim 9
Dependent Claim
60 words
A process for the preparation of thermally stable, substantially polycrystalline silicon carbide fibers comprising: forming fibers from a preceramic polymer comprising a polycarbosilane resin; infusibilizing said fibers; and pyrolyzing said fibers at a temperature of greater than about 1600° C. in a non-oxidizing environment wherein at least about 0.2% by weight boron is incorporated during said infusibilization or said pyrolysis.
Claim 10
Dependent Claim
28 words
The process of claim 7 in which said substantially polycrystalline silicon carbide fibers have at least about 75% crystallinity and a density of at least about 2.9 g/cc.
Claim 11
Dependent Claim
28 words
The process of claim 8 in which said fibers are formed by a spinning method selected from the group consisting of melt spinning, wet spinning and dry spinning.
Claim 12
Dependent Claim
18 words
The process of claim 7 in which said polycarbosilane comprises a polymer with repeating (--SiHCH 3 --CH2--) units.
Claim 13
Dependent Claim
37 words
The process of claim 9 in which said fibers are infusibilized by a method selected from the group consisting of air treatment, exposure to gamma irradiation treatment, exposure to UV light and exposure to an oxidizing agent.
Claim 14
Dependent Claim
38 words
The process of claim 11 in which boron is incorporated into said fiber during the early stages of said pyrolyzing step by exposing said fiber to a boron containing gas at a temperature less than about 500° C.
Claim 15
Dependent Claim
23 words
The process of claim 12 in which the boron containing gas is selected from the group consisting of boron hydrides, borazine or trichloroborazine.
Claim 16
Dependent Claim
36 words
The process of claim 9 in which the fibers are pyrolyzed to a temperature of about 1800° C. for about 1 hour in an atmosphere selected from the group consisting of argon, helium and mixtures thereof.
Claim 17
Dependent Claim
26 words
The process of claim 14 in which boron is incorporated into said fiber during said infusibilization step by exposing said fiber to a boron containing gas.
Claim 18
Dependent Claim
13 words
The process of claim 15 in which said boron containing gas comprises diborane.
Claim 19
Dependent Claim
41 words
The process of claim 15 in which said exposure to a boron containing gas comprises sequential treatment with a boron containing gas selected from the group consisting of boron trichloride, boron tribromide and boron trifluoride followed by treatment with an amine.
Claim 20
Dependent Claim
43 words
The process of claim 15 in which said exposure to a boron containing gas comprises sequential treatment with nitric oxide followed by treatment with a boron containing gas selected from the group consisting of boron trichloride, boron tribromide and boron trifluoride or diborane.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1994-12-09 | 1995-06-10 | 1995-12-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-12-09 | 1999-06-10 | 1999-12-10 | $3760.00 | Window Closed / Lapsed |
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