Effect of La₂O₃ additives on the strength and microstructure of mullite ceramics obtained from coal gangue and ¦Ã-Al₂O₃

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• 作者：Haipeng Ji ; Minghao Fang ; Zhaohui Huang ; ^{huang118@cugb.edu.cn} ; Kai Chen ; Youguo Xu ; Yan'gai Liu ; Juntong Huang
• 关键词：B. Microstructure ; C. Strength ; D. Clays ; D. Mullite
• 刊名：Ceramics International
• 出版年：2013
• 出版时间：August, 2013
• 年：2013
• 卷：39
• 期：6
• 页码：6841-6846
• 全文大小：892 K

文摘

Self-strengthened mullite ceramics with interlocking columnar grains formed through enhanced anisotropic growth by adding La₂O₃ were prepared from coal gangue and ¦Ã-Al₂O₃ within the temperature range 1400-1550 ¡ãC and holding time of 4 h. The effects of La₂O₃ on the bending strength, microstructural evolution, and phase composition were studied. The results showed that the bending strength of the as-prepared ceramics was significantly improved by the addition of La₂O₃. For samples sintered at 1550 ¡ãC, the bending strength increased from 64 MPa to 218 MPa as the La₂O₃ content increased from 0 mol % to 10 mol % . X-ray diffraction analysis suggested that the formation temperature of secondary mullite was lowered by about 50 ¡ãC by adding La₂O₃. Scanning electron micrographs revealed that the La₂O₃-added mullite mostly existed in long, columnar form, with aspect ratios of 3-6, forming an interlocking network structure. The interlocking mullite columns, together with the enhanced densification behaviour, contributed to the improved bending strength.