Claims
- 1. A method of differential conversion of an exposed outer surface of a carbon-carbon composite material into a silicon carbide-hybridized carbon-carbon to provide a dense and chemically-resistant outer surface, said method comprising:
- (i) providing a carbon-carbon composite material with an exposed outer surface for said conversion, said carbon-carbon composite material selected from the group consisting of graphite carbon fiber-carbon matrix material, carbon fiber-carbon matrix material, and carbon-carbon matrix material;
- (ii) providing silicon monoxide vapor prepared by the chemical reaction as follows: Si (liquid)+SiO.sub.2 (gaseous).fwdarw.2 SiO (vapor), said silicon monoxide vapor having a concentration;
- (iii) exposing said carbon-carbon composite material to said silicon monoxide vapor in a reaction chamber at a temperature from about 1500.degree. C. to about 1700.degree. C. and a time period from about 30 to about 60 minutes to infiltrate said silicon monoxide into said carbon-carbon composite material wherein said infiltration occurs by the following reaction: 2SiO (vapor)+2C (solid).fwdarw.SiC (solid)+CO (gaseous) to thereby achieve differential conversion with a conversion depth from about 50 to 100 mils, said conversion depth for said carbon-carbon composite material controlled by the concentration of silicon monoxide vapor;
- (iv) purging said reaction chamber of by-products of reaction and of any unreacted silicon monoxide;
- (v) cooling said carbon-carbon composite material; and
- (vi) removing said carbon-carbon composite material.
- 2. The method of claim 1 wherein said differential conversion increases the density of said exposed surface of the carbon-carbon composite material from 1.45 g/cc 3.21 g/cc.
- 3. The method of claim 1 wherein said carbon-carbon composite material is a graphite fiber-carbon matrix material which has a higher percentage of graphitic carbon fibers at the surface, said graphitic carbon fibers having a transverse fiber orientation.
- 4. The method of claim 3 wherein said temperature is about 1700 .degree. C.
Parent Case Info
This is a application continuation, of application Ser. No. 07/941,818, filed Sep. 8, 1992, now abandoned.
DEDICATORY CLAUSE
The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalties thereon.
US Referenced Citations (10)
Continuations (1)
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Number |
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941818 |
Sep 1992 |
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