Characterisation of sol-gel derived alumina-silica matrices for continuous fibre reinforced composites
✍ Scribed by J. Wu; M. Chen; F.R. Jones; P.F. James
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 1018 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0955-2219
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✦ Synopsis
Bulk gels corresponding to an oxide composition of 3A1203.2Si02, prepared from a sol with a high solids yield using submicron alumina powder and colloidal silica sol as precursors, were sintered to over 99% of theoretical density after 2 h at 1300°C. Denstfication occurred by viscous flow of the amorphous silica matrix containing well dispersed alumina particles. After 2 h at 1600°C almost complete crystallisation to mullite occurred. Untform unidirectional carbon jibre reinforced composites were produced by a single stage infiltration of fibres, using the above sol, and hot-pressing either at 1300 or at 1400°C to 98 and 97% of the theoretical density respectively. The composites, with a matrix predominantly of silica glass and dispersed alumina particles, exhibited non-brittle failure with mean flexural strengths of 720 and 766 MPa for hot-pressing at 1300 and 1400°C respectively. Extensive fibre pull-out during testing indicated a relatively weak bond between the jibres and the matrix, and transmission electron microscopy revealed no evidence of chemical interactions at the interface.