US4194027A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of coating with homogeneous pyrocarbon
Assignee: General Atomics Corp
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Filing: 1975-04-21
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Granted: 1980-03-18
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Expires: 1995-04-21
Abstract
Abstract Items are coated with substantially homogeneous pyrolytic carbon by first heating them to the desired temperature, e.g., about 1200° C. to 1600° C. in a nonoxidizing atmosphere. A mixture of gas including an inert gas portion and a hydrocarbon portion is supplied to the heated enclosure at a rate so that the mixture approaches the temperature of the heated items and the hydrocarbon decomposes. The hydrocarbon portion includes between about 25 and about 60 volume percent acetylene and the remainder propylene. The exothermic characteristics of acetylene is such that the heat given off upon decomposition is sufficient to sustain the coating reaction.
Inventors
- 👤 Charles C. Adams
- 👤 Curtis L. Allen
- 👤 Gottfried E. A. Besenbruch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:49
CPC Classifications
C; C23; C23C; C23C16/00; C23C16/22; C23C16/26; G; G21; G21C; G21C3/00; G21C3/42; G21C3/58; G21C3/62; G21C3/626; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
140 words
A method of coating items with substantially homogeneous pyrolytic carbon, which method comprises heating the items to be coated to a temperature of between about 1000° C. and about 2000° C. in an enclosure and flowing a mixture of gases through said enclosure at a rate so that said gases are heated to a temperature approaching the temperature of said items causing gaseous decomposition and deposition of pyrolytic carbon, said mixture containing an inert gas portion and a hydrocarbon portion, said hydrocarbon portion including between about 25 v/o and about 65 v/o of acetylene and the remainder of propylene, said mixture composition being such that the amount of heat needed to raise said gaseous mixture from the temperature at which it enters the enclosure to said decomposition temperature is approximately balanced against the heat given off by the hydrocarbon decomposition.
Claim 2
Independent Claim
140 words
A method of coating items with substantially homogeneous pyrolytic carbon, which method comprises heating the items to be coated to a temperature of between about 1000° C. and about 2000° C. in an enclosure and flowing a mixture of gases through said enclosure at a rate so that said gases are heated to a temperature approaching the temperature of said items causing gaseous decomposition and deposition of pyrolytic carbon, said mixture containing an inert gas portion and a hydrocarbon portion, said hydrocarbon portion including between about 25 v/o and about 65 v/o of acetylene and the remainder of propylene, said mixture composition being such that the amount of heat needed to raise said gaseous mixture from the temperature at which it enters the enclosure to said decomposition temperature is approximately balanced against the heat given off by the hydrocarbon decomposition.
Claim 3
Dependent Claim
21 words
A method of coating in accordance with claim 1 wherein at least about 90 mole percent of said hydrocarbon is decomposed.
Claim 4
Dependent Claim
22 words
A method of coating in accordance with claim 1 wherein said hydrocarbon includes between about 50 and about 55 volume percent acetylene.
Claim 5
Dependent Claim
23 words
A method in accordance with claim 1 wherein said items are heated to a temperature between about 1200° C. and about 1600° C.
Claim 6
Dependent Claim
26 words
A method in accordance with claim 1 wherein a sufficient quantity of small particles are present in said enclosure to cause isotropic pyrocarbon to be deposited.
Claim 7
Dependent Claim
33 words
A method in accordance with claim 5 wherein said enclosure is a part of a fluidized bed apparatus and wherein the flow rate of said gaseous mixture is sufficient to levitate said particles.
Claim 8
Dependent Claim
25 words
A method in accordance with claim 5 wherein said carbon has a density of between about 1.7 and about 2 grams per cm 3 .
Claim 9
Dependent Claim
17 words
A method in accordance with claim 7 wherein said coating is carried out at about atmospheric pressure.
Claim 10
Dependent Claim
23 words
A method in accordance with claim 8 wherein said inert gas constitutes between about 20 v/o and about 65 v/o of said mixture.
Claim 11
Dependent Claim
24 words
A method in accordance with claim 7 wherein said isotropic carbon is deposited at a rate of at least about 3 microns per minute.
Claim 12
Dependent Claim
23 words
A method in accordance with claim 1 wherein said inert gas constitutes between about 35 and about 45 volume percent of said mixture.
References Cited (Backward Citations)
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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) | 1983-03-18 | 1983-09-17 | 1984-03-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-18 | 1987-09-17 | 1988-03-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-18 | 1991-09-17 | 1992-03-18 | $7700.00 | Window Closed / Lapsed |