Effect of glass sealing on the oxidation behavior of three dimensional C/SiC composites in air

Citation
Lf. Cheng et al., Effect of glass sealing on the oxidation behavior of three dimensional C/SiC composites in air, CARBON, 39(8), 2001, pp. 1127-1133
Citations number
9
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
CARBON
ISSN journal
0008-6223 → ACNP
Volume
39
Issue
8
Year of publication
2001
Pages
1127 - 1133
Database
ISI
SICI code
0008-6223(2001)39:8<1127:EOGSOT>2.0.ZU;2-R
Abstract
A borosilicate glass which consisted of 40-45 mol.% B2O3 and 55-60 mol.% Si O2 was used as a sealant for the C/SiC composites with and without a Si-Zr coating, and the oxidation behavior of the C/SiC composites in air was inve stigated. The glass increased greatly the oxidation resistance by decreasin g the maximum weight loss and the cracking temperature range below 1000 deg reesC as well as by lowering the transition temperature. The effective sear ing temperature of the glass was from 700 to 900 degreesC. The glass began losing its sealing ability very rapidly above 900 degreesC, and lost this a bility completely above 1000 degreesC. After oxidation for 20 h in an air a tmosphere with a large temperature gradient from 350 to 1300 degreesC, the strengths of the composite with both the Si-Zr coating and the glass sealan t were maintained over the whole temperature range. The composite with the sealant only lost strength mostly at high temperature and that with only th e coating lost almost all its strength at low temperature, and both of the composites could not be used in environments with a temperature gradient. T he sealing temperature range of the glass was narrower than the cracking te mperature range of the composite. No matter how the composition was changed , the borosilicate glass could not seal over the whole cracking temperature range of the composite at the same time for long-term use. (C) 2001 Publis hed by Elsevier Science Ltd.