| Autor: |
R. A. Lowden, S. Nijhawant, L. Riester, P. F. Tortorelli |
| Rok vydání: |
2008 |
| Předmět: |
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| Zdroj: |
Proceedings of the 17th Annual Conference on Composites and Advanced Ceramic Materials: Ceramic Engineering and Science Proceedings |
| DOI: |
10.1002/9780470314180.ch60 |
| Popis: |
Thermogravimetric analysis was used to study the reaction kinetics associated with high-temperature air oxidation of graphite- or BN-coated Nicalon-reinforced SiC composites. For those with graphite interlayers, the shapes of the thermogravimetric curves, and the dependencies of weight changes on interfacial layer thickness and exposure temperature, could be explained on the basis of concurrent reactions associated with oxidation of the graphite and the formation of SiO[sub 2] on the matrix and fibers. The oxidation resistance of SiC with BN-coated Nicalon fibers was significantly better than when graphite coatings were used. Flexure tests of Nicalon/graphite/SiC previously oxidized in air at 950[degree]C revealed that degradation of fracture resistance can be detected after very short exposure times (less than 1 h). Accordingly, a knowledge of reaction kinetics is important in characterizing environmental effects on fracture and damage and in predicting the rate of properties degradation. 12 refs, 4 figs, 2 tabs. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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