Processing and Microstructure of Mullite-Zirconia Composites Prepared from Sol-Gel Powders |
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Authors: | QI-MING YUAN JIA-QI TAN JI-YAO SHEN XUAN-HUI ZHU ZHENG-FANG YANG |
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Affiliation: | Ceramic Division, Department of Materials Science and Engineering, Tianjin University, Tianjin, China |
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Abstract: | A high-purity stoichiometric mullite precursor was obtained by hydrolysis of the alkoxides Al(OC3H7)3 and Si(OC2H2)4. Fully sintered mullite ceramics can be prepared from sol-gel powders by sintering them at 1600°C for 4 h in air with the addition of 15 to 20 Vol% ZrO2 or 1 to 3 mol% Y2O3 or both. Introduction of 1 to 3 mol% Y2O3 aids the retention of tetragonal ZrO2; the volume fraction of t -ZrO2 retained increases with increasing Y2O3 content. The maximum t -ZrO2 retained reaches 34% in a matrix of synthetic mullite with 3 mol% Y2O3, but most of this t -ZrO2 does not undergo stress-induced transformation during grinding. |
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