Synthesis of mullite composites from powder mixtures of alumina, silica and zirconia
- Tatung Institute of Technology, Taipei (Taiwan, Province of China)
Mullite and its composites have potential as good structural ceramics. However, the difficulty in sintering mullite composites needs to be overcome. Considering the sintering problem, the fabrication of dense mullite composites via viscous flow of amorphous silica appears to be an excellent method. In this study, mullite/yttria-zirconia composites were viscous and reaction sintered from mixtures of alumina, amorphous silica and 3 mol% yttria-zirconia powders, which were processed by conventional procedures such as wet ball-milling and dry-pressing. The results showed that the densification and phase formation depended on compositions as well as sintering temperatures. Dense ({approximately}97% T.D.) mullite/yttria-zirconia composites could be achieved when samples contained 20 vol% of yttria-zirconia and sintered at 1500{degrees}C for 2 hours in air. The addition of yttria-zirconia promoted densification and retarded the crystallization of cristobalite. It also lowered the mullitization temperature from 1500{degrees}C to 1400{degrees}C. Microstructure of mullite/20 vol% yttria-zirconia sintered 1500{degrees}C showed that the mullite grains were equiaxed or elongated. The zirconia grains were mostly located at grain boundaries, indicating the inhibiting effects of zirconia on mullite grain growth.
- OSTI ID:
- 96549
- Report Number(s):
- CONF-940416--; CNN: Grant NSC82-0113-E-036-053-T
- Country of Publication:
- United States
- Language:
- English
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