Mullite formation in kaolinite-{alpha}-alumina
- Univ. of California, Berkeley (United States). Dept. of Materials Science and Mineral Engineering
- Inst. de Ceramica y Vidrio, Madrid (Spain). Dept. of Ceramics
The primary and secondary mullite formation in high purity kaolinite-{alpha}-alumina have been studied by conventional processing, XRD, TEM, AEM, and optical microscopy. After a 4h firing at 1,300 C or below, only monosized primary mullite was formed in platy kaolinite, leaving {alpha}-alumina largely inert. Bimodal mullite crystals demonstrating secondary mullite nucleation and primary mullite growth were observed after 4h firing at 1,400 C. At 1,400 C and above, the rapid kinetics of secondary mullite formation, the characteristics of the co-existing glassy phase and the microstructure, as well as the evidence of liquid phase sintering strongly support that solution-precipitation via a transitory liquid phase was the major mechanism for secondary mullite formation. Secondary mullite formation via inter-diffusion, though also observable, was considered as a minor route in the kaolinite-{alpha}-alumina reaction.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 143149
- Journal Information:
- Acta Metallurgica et Materialia, Vol. 42, Issue 2; Other Information: PBD: Feb 1994
- Country of Publication:
- United States
- Language:
- English
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