Hydrothermal degradation of chemical vapour deposited SiC fibres

The interaction of chemical vapour-deposited (CVD) SiC fibres with H2O at 200 MPa and 400–700°C (673–973K), was investigated. With increasing temperature and time, the smooth surface of the amorphous SiC fibre becomes rough and sponge-like. This modification can be controlled by adjusting temperatur...

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Bibliographic Details
Published in:Journal of materials science 1998-09, Vol.33 (17), p.4357-4364
Main Authors: KRAFT, T, NICKEL, K. G, GOGOTSI, Y. G
Format: Article
Language:English
Subjects:
Applied sciences
Building materials. Ceramics. Glasses
Carbon
Ceramic and carbon fibers
Ceramic industries
Chemical industry and chemicals
Chemical vapor deposition
Cristobalite
Exact sciences and technology
Fibers
Hydrothermal treatment
Materials science
Organic chemistry
Silicon dioxide
Technical ceramics
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Summary:The interaction of chemical vapour-deposited (CVD) SiC fibres with H2O at 200 MPa and 400–700°C (673–973K), was investigated. With increasing temperature and time, the smooth surface of the amorphous SiC fibre becomes rough and sponge-like. This modification can be controlled by adjusting temperature and duration of the hydrothermal treatment. CVD SiC dissolves in supercritical water in a first order reaction with Ea=150 kJ mol-1. According to thermodynamic calculations, the main products are SiO2, CH4 and H2. The formation of carbon is also predicted. Films of amorphous and graphitic carbon have been observed, but only small areas of the fibres were coated with carbon. Amorphous silica, quartz, cristobalite and keatite were deposited on the surface of fibres in larger quantities © 1998 Kluwer Academic Publishers
ISSN:0022-2461
1573-4803
DOI:10.1023/A:1004480814477