US4358486A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Densification of porous refractory substrates
Assignee: National Aeronautics and Space Administration
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Filing: 1981-05-22
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Granted: 1982-11-09
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Expires: 2001-05-22
Abstract
Abstract A hydrolyzed tetraethyl orthosilicate is applied to the surface of a porous refractory substrate following which the substrate is heated to a temperature and for a period of time sufficient to bond the silica released from the tetraethyl orthosilicate to the substrate thereby densifying and strengthening the surface.
Inventors
- 👤 Glenn M. Ecord
- 👤 Calvin Schomburg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 00:04
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B41/45; C04B41/50; C04B41/5025; C04B41/5035; C04B41/80; C04B41/81; C04B41/85; C04B41/87; Y; Y10; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/24992
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
51 words
A method of densifying a porous refractory substrate comprising penetrating a surface of said substrate with a densifying agent comprised of a hydrolyzed tetraethyl orthosilicate, and heating said substrate at an elevated temperature and for a period of time sufficient to bond silica released from said densifying agent to said substrate.
Claim 2
Independent Claim
51 words
A method of densifying a porous refractory substrate comprising penetrating a surface of said substrate with a densifying agent comprised of a hydrolyzed tetraethyl orthosilicate, and heating said substrate at an elevated temperature and for a period of time sufficient to bond silica released from said densifying agent to said substrate.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein said substrate comprises silica fibers rigidized with a high purity silica binder.
Claim 4
Dependent Claim
107 words
The method of claim 2 wherein: a. applying a first coating of said densifying agent to said substrate in an amount of about 0.25 cc/cm 2 of surface area; b. heating said substrate to a temperature of about 260° F. for a period of time to bond silica released from said densifying agent to said substrate; c. applying a second coating of said densifying agent to said substrate in an amount of about 0.25 cc/cm 2 of surface area; d. heating said substrate to a temperature of about 350° F. for a period of time sufficient to bond silica released from said densifying agent to said substrate.
Claim 5
Dependent Claim
19 words
The method of claim 3 wherein said densifying agent penetrates said substrate to a depth of about 0.125 inches.
Claim 6
Dependent Claim
15 words
The method of claim 3 wherein steps c and d or variations thereof are repeated.
Claim 7
Dependent Claim
36 words
The method of claim 2 wherein the amount of said densifying agent applied to said substrate is such as to provide a total average weight increase of greater than about 0.12 grams/square centimeter of densified surface.
Claim 8
Dependent Claim
12 words
The method of claim 1 wherein said densifying agent contains a dye.
Claim 9
Dependent Claim
60 words
The method of claim 1 wherein said densifying agent is prepared by admixing said tetraethyl orthosilicate and 0.05 N hydrochloric acid solution in a ratio of 100 parts by volume of said tetraethyl orthosilicate to 22 parts by volume of said hydrochloric acid solution, and admixing said tetraethyl orthosilicate and said hydrochloric acid solution until a clear liquid is obtained.
Claim 10
Dependent Claim
12 words
The method of claim 8 wherein said densifying agent contains a dye.
Claim 11
Dependent Claim
19 words
The method of claim 1 wherein the densified substrate is used as a base for subsequent coatings or covers.
Claim 12
Dependent Claim
22 words
The method of claim 1 wherein the densified substrate is used for increased hardness or damage resistance of the softer original refractory.
Claim 13
Dependent Claim
28 words
The method of claim 1 wherein a densified area or volume is used as a bearing or loading surface to prevent pullout of fasteners or other inserted devices.
References Cited (Backward Citations)
US4124732A
Cited
US4093771A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-11-08 | 1986-05-10 | 1986-11-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-08 | 1990-05-10 | 1990-11-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-08 | 1994-05-10 | 1994-11-09 | $7700.00 | Window Closed / Lapsed |