Interface modification during oxidation of a glass-ceramic matrix/SiC fibre composite
- CEIT, San Sebastian (Spain)
- Oak Ridge National Lab., TN (United States)
Oxidation heat treatments between 375{degrees}C and 600{degrees}C for 100 hours in air, have been performed on the calcium aluminosilicate glass-ceramic matrix/SiC fibre reinforced composite CAS/Nicalon (manufactured by Corning, USA). Using a commercial nano-indentation system to perform fibre push-down tests, the fibre-matrix interfacial debond fracture surface energy (G{sub i}) and frictional shear stress ({tau}) have been determined. Modification of interface properties, compared to the as-fabricated material, was observed at heat treatment temperatures as low as 375{degrees}C, where a significant drop in G{sub i} and an increase in {tau} were recorded. With 450{degrees}C, 525{degrees}C and 600{degrees}C heat treatments, an increase in G{sub i} but a dramatic increase in {tau} were recorded. Under four-point flexure testing, the as fabricated and the 375{degrees}C heat treated materials displayed tough, composite behaviour with extensive fibre pull out, but at {ge}450{degrees}C, brittle failure with minimal fibre pull out, was observed. This transition from tough mechanical response to one of brittleness is due to the large increase in {tau} reducing fibre pull out to a minimum and therefore reducing the total required work of fracture. The large increases in {tau} and G{sub i} have been attributed to the oxidative removal of the lubricating, carbon interface and the compressive residual stresses across the interface.
- OSTI ID:
- 567471
- Report Number(s):
- CONF-960106-; TRN: 98:000276-0018
- Resource Relation:
- Conference: 20. annual conference on composites, advanced ceramics, materials and structures-B, Cocoa Beach, FL (United States), 7-11 Jan 1996; Other Information: PBD: 1996; Related Information: Is Part Of Proceedings of the 20th annual conference on composites, advanced ceramics, materials, and structures - B; Greenhut, V.; PB: 465 p.
- Country of Publication:
- United States
- Language:
- English
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