US4465777A
Expired / Lapsed
US
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Composition and method for forming a protective coating on carbon-carbon substrates
Assignee: Lockheed Martin Corp
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Filing: 1982-12-28
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Granted: 1984-08-14
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Expires: 2002-12-28
Abstract
Abstract In accordance with the invention, a composition of matter is provided for forming a coating for protecting carbonaceous substrates from degradation at elevated temperatures. The composition is a mixture of particulate silicon, silicon carbide and boron. The mixture contains between about 25% and 40% silicon by weight of the total composition, between about 50% and 70% by weight silicon carbide by weight of the total composition, between about 1% and 15% boron by weight of the total composition and a minor amount of magnesium oxide. The method is provided for forming a primary protective coating on carbonaceous substrates utilizing the aforesaid mixture. An enhancement coating is provided for sealing the primary coating in applications where the substrate will be subjected to elevated temperatures and temperature cycling.
Inventors
- 👤 David M. Shuford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:37
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B35/00; C04B35/71; C04B35/78; C04B35/80; C04B35/83; C04B41/45; C04B41/4505; C04B41/50; C04B41/5053; C04B41/5057; C04B41/5059; C04B41/52; C04B41/80; C04B41/81; C04B41/85; C04B41/87; C04B41/89; Y; Y10; Y10T; Y10T428/00; Y10T428/30
Claims Analysis
Total Claims: 46
Claim 1
Independent Claim
79 words
A composition for forming a coating for protecting a carbonaceous substrate from degradation at elevated temperatures comprising a mixture of: (a) between about 25% and 40% particulate silicon by weight of the total composition; (b) between about 50% and 70% particulate silicon carbide by weight of the total composition; (c) between about 1% and 15% of particulate boron by weight of the total composition; and (d) a minor amount of particulate magnesium oxide for facilitating formation of the coating.
Claim 2
Dependent Claim
79 words
A composition for forming a coating for protecting a carbonaceous substrate from degradation at elevated temperatures comprising a mixture of: (a) between about 25% and 40% particulate silicon by weight of the total composition; (b) between about 50% and 70% particulate silicon carbide by weight of the total composition; (c) between about 1% and 15% of particulate boron by weight of the total composition; and (d) a minor amount of particulate magnesium oxide for facilitating formation of the coating.
Claim 3
Dependent Claim
61 words
The composition of matter as recited in claim 1 wherein: (a) silicon carbide is present in an amount of about 60 % by weight of the total composition; (b) silicon is present in an amount of about 35% by weight of the total compositon; and (c) boron is present in an amount of about 5% by weight of the total composition.
Claim 4
Dependent Claim
22 words
The composition of matter as recited in claims 1 or 2 wherein the magnesium oxide is an impurity present in the boron.
Claim 5
Independent Claim
139 words
A method for forming a coating on a carbonaceous substrate for protecting the substrate from degradation at elevated temperatures comprising: (a) forming a composition of an essentially uniform mixture of particulate silicon present in an amount of between about 25% and 40% by weight of the total composition, particulate silicon carbide present in an amount of between about 50% and 70% by weight of the total composition, particulate boron present in an amount of between about 1% and 15% by weight of the total composition and a minor amount of magnesium oxide; (b) encasing the substrate to be coated with a release agent; (c) contacting the encased substrate with said mixture; and (d) thereafter sufficiently heating said mixture and the carbon-carbon substrate encased by release agent to form the coating on the surface of the substrate from said mixture.
Claim 6
Independent Claim
139 words
A method for forming a coating on a carbonaceous substrate for protecting the substrate from degradation at elevated temperatures comprising: (a) forming a composition of an essentially uniform mixture of particulate silicon present in an amount of between about 25% and 40% by weight of the total composition, particulate silicon carbide present in an amount of between about 50% and 70% by weight of the total composition, particulate boron present in an amount of between about 1% and 15% by weight of the total composition and a minor amount of magnesium oxide; (b) encasing the substrate to be coated with a release agent; (c) contacting the encased substrate with said mixture; and (d) thereafter sufficiently heating said mixture and the carbon-carbon substrate encased by release agent to form the coating on the surface of the substrate from said mixture.
Claim 7
Dependent Claim
32 words
The method as recited in claim 4 wherein said mixture and the substrate encased with said release agent are maintained in the temperature range of between about 3075° F. and 3350° F.
Claim 8
Dependent Claim
23 words
The method as recited in claim 5 wherein said temperature is maintained in said temperature range for a period of about four hours.
Claim 9
Dependent Claim
37 words
The method as recited in claim 4 wherein said mixture contains about 60% by weight silicon carbide, about 35% by weight silicon and about 5% by weight boron, said boron containing said minor amount of magnesium oxide.
Claim 10
Dependent Claim
62 words
The method as recited in claim 4 wherein said mixture and the substrate encased by said release agent is heated to a temperature of about 2800° F., thereafter maintaining the mixture and substrate at a temperature of about 3100° F. for about two hours and thereafter maintaining the mixture and substrate at a temperature of about 3300° F. for about two hours.
Claim 11
Dependent Claim
14 words
The method as recited in claim 4 wherein said release agent comprises ash-free paper.
Claim 12
Dependent Claim
22 words
The method as recited in claim 4 wherein said release agent further comprises a hydroxypropyl methyl cellulose solution containing filter paper pulp.
Claim 13
Dependent Claim
21 words
The method as recited in claim 10 wherein said release agent is dried and cured prior to contacting with said mixture.
Claim 14
Dependent Claim
29 words
The method as recited in claim 4 wherein said mixture and the encased substrate is contained within a graphite retort during heating of said mixture and the encased substrate.
Claim 15
Dependent Claim
24 words
The method as recited in claim 4 further comprising forming an enhancement coating after formation of said primary coating for sealing the primary coating.
Claim 16
Dependent Claim
68 words
The method as recited in claim 13 wherein the method for forming said enhancement coating comprises: (a) impregnating the primary coating with tetraethyl orthosilicate; (b) heat curing the tetraethyl orthosilicate applied to said primary coating; (c) thereafter applying a mixture of a liquid alkali silicate and particulate silicon carbide to the primary coating; and (d) curing the alkali silicate and silicon carbide mixture applied to the primary coating.
Claim 17
Dependent Claim
39 words
The method as recited in claim 14 wherein said tetraethyl orthosilicate is cured by heating between about 225° F. and 625° F. and said alkali silicate and silicon carbide mixtures are cured by heating up to about 625° F.
Claim 18
Dependent Claim
59 words
The method as recited in claim 13 wherein the method for forming said enhancement coating comprises: (a) applying a mixture of an aqueous monoaluminum phosphate solution containing particulate alumina and silicon carbide to the surface of the primary coating; and (b) heat curing the aqueous monoaluminum phosphate solution containing particulate alumina and silicon carbide applied to the primary coating.
Claim 19
Dependent Claim
62 words
The method as recited in claim 16 wherein the aqueous monoaluminum phoshate solution containing silicon carbide and alumina is allowed to dry at ambient temperature and is thereafter heat cured by maintaining at a temperature of about 200° F. for about two hours, then at about 400° F. for about two hours and finally at about 600° F. for about four hours.
Claim 20
Dependent Claim
76 words
The method as recited in claim 13 wherein the method for forming said enhancemnt coating comprises: (a) impregnating the primary coating with tetraethyl orthosilicate; (b) heat curing the tetraethyl orthosilicate applied to the primary coating; (c) hereafter applying a mixture of an aqueous sodium borate sodium silicate solution and particulate silicate carbide to the primary coating; and (d) curing the mixture of the aqueous sodium borate-sodium silicate and particulate silicon carbide applied to the primary coating.
Claim 21
Dependent Claim
31 words
The composition of matter as recited in claim 3 wherein said magnesium oxide is present in an amount of from about 2 to about 8% based on the weight of boron.
Claim 22
Dependent Claim
22 words
The composition of claim 19 wherein said magnesium oxide is present in an amount of about 4% by weight of said boron.
Claim 23
Dependent Claim
22 words
The composition of claims 1 or 2 wherein said particulate silicon has a particle size of about 325 Tyler standard screen scale.
Claim 24
Dependent Claim
24 words
The composition of claims 1 or 2 wherein said particulate silicon carbide has a particle size of between about 4.5 and about 20.5 microns.
Claim 25
Dependent Claim
22 words
The composition of claims 1 or 2 wherein said boron has a particle size of between about 0.5 and about 20 microns.
Claim 26
Dependent Claim
120 words
A composition for forming a coating for protecting a carbonaceous substrate from degradation by oxidation comprising a mixture of: (a) between about 25 and 40% by weight of the total composition of particulate silicon having a particle size of about 325 Tyler standard screen scale; (b) between about 50 and 70% particulate silicon carbide by weight of the total composition, said particulate silicon carbide having a particle size of between about 4.5 and 20.5 microns; (c) between about 1% and 15% of particulate boron by weight of the total composition, said particulate boron having a particle size of between about 0.5 and about 20 microns; and (d) a minor amount of particulate magnesium oxide for facilitating formation of the coating.
Claim 27
Dependent Claim
120 words
A composition for forming a coating for protecting a carbonaceous substrate from degradation by oxidation comprising a mixture of: (a) between about 25 and 40% by weight of the total composition of particulate silicon having a particle size of about 325 Tyler standard screen scale; (b) between about 50 and 70% particulate silicon carbide by weight of the total composition, said particulate silicon carbide having a particle size of between about 4.5 and 20.5 microns; (c) between about 1% and 15% of particulate boron by weight of the total composition, said particulate boron having a particle size of between about 0.5 and about 20 microns; and (d) a minor amount of particulate magnesium oxide for facilitating formation of the coating.
Claim 28
Dependent Claim
63 words
The composition of matter as recited in claim 24 wherein: (a) said silicon carbide is present in an amount of about 60% by weight of the total composition; (b) said silicon is present in an amount of about 35% by weight of the total composition; and (c) said boron is present in an amount of about 5% by weight of the total composition.
Claim 29
Dependent Claim
35 words
The compositions as recited in claims 24 or 25 wherein the magnesium oxide is an impurity present in the boron in an amount of from about 2 to about 8% by weight of the boron.
Claim 30
Dependent Claim
26 words
A composition of matter as recited in claim 26 wherein the magnesium oxide is present in an amount of about 4% by weight of said boron.
Claim 31
Dependent Claim
81 words
A coated substrate resistant to degradation due to exposure to oxygen at elevated temperatures comprising: (a) a carbonaceous substrate; and (b) a coating on said substrate and comprising between about 25 and 40% by weight particulate silicon, between about 50 and 70% by weight particulate silicon carbide, between about 1 and 15% by weight of particulate boron and a minor amount of particulate magnesium oxide for facilitating formation of the coating, said percentages being based on the weight of the coating.
Claim 32
Dependent Claim
81 words
A coated substrate resistant to degradation due to exposure to oxygen at elevated temperatures comprising: (a) a carbonaceous substrate; and (b) a coating on said substrate and comprising between about 25 and 40% by weight particulate silicon, between about 50 and 70% by weight particulate silicon carbide, between about 1 and 15% by weight of particulate boron and a minor amount of particulate magnesium oxide for facilitating formation of the coating, said percentages being based on the weight of the coating.
Claim 33
Dependent Claim
27 words
The coated substrate of claim 28 wherein said coating comprises about 60% by weight silicon carbide, about 35% by weight silicon and about 5% by weight boron.
Claim 34
Dependent Claim
19 words
The coated substrate of claims 28 or 29 wherein the magnesium oxide is an impurity present in the boron.
Claim 35
Dependent Claim
30 words
The coated substrate of claim 30 wherein said magnesium oxide is present in an amount of from about 2 to about 8% by weight of the boron in said coating.
Claim 36
Dependent Claim
23 words
The coated substrate of claim 31 wherein said magnesium oxide is present in an amount of about 4% by weight of said boron.
Claim 37
Dependent Claim
20 words
The coated substrate of claim 28 and further comprising an enhancement coating formed from impregnating the coating with tetraethyl orthosilicate.
Claim 38
Dependent Claim
28 words
The coated substrate of claim 28 and further comprising an enhancement coating formed from a mixture of an aqueous monoaluminum phosphate solution containing particulate alumina and silicon carbide.
Claim 39
Independent Claim
86 words
A method for protecting a carbonaceous substrate from degradation by oxidation at elevated temperatures comprising forming a coating on said substrate, said coating comprising a mixture of: (a) between about 25 and 40% particulate silicon by weight of the total composition; (b) between about 50 and 70% particulate silicon carbide by weight of the total composition; (c) between about 1 and 15% of particulate boron by weight of the total composition; and (d) a minor amount of particulate magnesium oxide for facilitating formation of the coating.
Claim 40
Independent Claim
86 words
A method for protecting a carbonaceous substrate from degradation by oxidation at elevated temperatures comprising forming a coating on said substrate, said coating comprising a mixture of: (a) between about 25 and 40% particulate silicon by weight of the total composition; (b) between about 50 and 70% particulate silicon carbide by weight of the total composition; (c) between about 1 and 15% of particulate boron by weight of the total composition; and (d) a minor amount of particulate magnesium oxide for facilitating formation of the coating.
Claim 41
Independent Claim
82 words
A method for protecting a carbonaceous substrate from degradation due to exposure to cyclical temperatures comprising forming on said substrate a coating comprising: (a) between about 25 and 40% particulate silicon by weight of the total composition; (b) between about 50 and 70% particulate silicon carbide by weight of the total composition; (c) between about 1 and 15% of particulate boron by weight of the total composition; and (d) a minor amount of particulate magnesium oxide for facilitating formation of the coating.
Claim 42
Independent Claim
82 words
A method for protecting a carbonaceous substrate from degradation due to exposure to cyclical temperatures comprising forming on said substrate a coating comprising: (a) between about 25 and 40% particulate silicon by weight of the total composition; (b) between about 50 and 70% particulate silicon carbide by weight of the total composition; (c) between about 1 and 15% of particulate boron by weight of the total composition; and (d) a minor amount of particulate magnesium oxide for facilitating formation of the coating.
Claim 43
Dependent Claim
60 words
A composition comprising: (a) between about 25 and 40% silicon by weight of the total composition; (b) between about 50 and 70% silicon carbide by weight of the total composition; (c) between about 1 and 15% boron by weight of the total composition; and (d) from about 2 to about 8% magnesium oxide based on the weight of said boron.
Claim 44
Dependent Claim
60 words
A composition comprising: (a) between about 25 and 40% silicon by weight of the total composition; (b) between about 50 and 70% silicon carbide by weight of the total composition; (c) between about 1 and 15% boron by weight of the total composition; and (d) from about 2 to about 8% magnesium oxide based on the weight of said boron.
Claim 45
Dependent Claim
17 words
The composition of claim 37 wherein said magnesium oxide is present as an impurity in the boron.
Claim 46
Dependent Claim
33 words
The composition of claim 39 wherein the magnesium oxide present as an impurity in the boron is present in an amount of from about 2 to about 8% by weight of the boron.
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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) | 1987-08-14 | 1988-02-13 | 1988-08-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-14 | 1992-02-13 | 1992-08-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-14 | 1996-02-13 | 1996-08-14 | $7700.00 | Window Closed / Lapsed |