Preparation of mullite by the reaction sintering of kaolinite and alumina
Journal
Journal of the European Ceramic Society
Journal Volume
20
Journal Issue
14-15
Pages
2519-2525
Date Issued
2000
Author(s)
Abstract
In the present study, mullite specimens and mullite/alumina composites are prepared by reaction sintering kaolinite and alumina at a temperature above 1000°C. The phase and microstructural evolution of the specimens and their mechanical properties are investigated. Primary mullite appears at a temperature around 1200°C. The alumina particles are inert to the formation of primary mullite. Alumina starts to react with the silica in glassy phase to form secondary mullite above 1300°C. The formation of secondary mullite decreases the amount of glassy phase. Furthermore, the addition of alumina reduces the size of mullite grains and their aspect ratio. The strength and toughness of the resulting mullite increase with the increase of alumina content; however, the mechanical properties of the mullite and mullite/alumina composites are lower than those of alumina for their relatively low density. (C) 2000 Elsevier Science Ltd. All rights reserved. In the present study, mullite specimens and mullite/alumina composites are prepared by reaction sintering kaolinite and alumina at a temperature above 1000°C. The phase and microstructural evolution of the specimens and their mechanical properties are investigated. Primary mullite appears at a temperature around 1200°C. The alumina particles are inert to the formation of primary mullite. Alumina starts to react with the silica in glassy phase to form secondary mullite above 1300°C. The formation of secondary mullite decreases the amount of glassy phase. Furthermore, the addition of alumina reduces the size of mullite grains and their aspect ratio. The strength and toughness of the resulting mullite increase with the increase of alumina content; however, the mechanical properties of the mullite and mullite/alumina composites are lower than those of alumina for their relatively low density.
Type
journal article