Difference of Mullite Whiskers between Ytterbia-Doped Aluminum Hydroxide-Silica Gel and Mechanochemical Process

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• 作者：Liang Long ; Li Jianbao ; Lin Hong ; Guo Gangfeng ; He Mingsheng
• 关键词：mullite whiskers ; ytterbia-doped ; gel ; mechanochemical ; rare earths
• 刊名：Journal of Rare Earths
• 出版年：2006
• 出版时间：December 2006
• 年：2006
• 卷：24
• 期：1, Supplement 1
• 页码：51-53
• 全文大小：335 K

文摘

A number of processing routes were developed for the synthesis of mullite whiskers. Mullite whiskers that were derived from ytterbia-doped aluminum hydroxide-silica gel were studied; another process for preparing mullite whiskers from Al₂O₃-SiO₂ oxide mixtures by mechanochemical method was encountered by chance. The method of ytterbia-doped aluminum hydroxide-silica was used to enhance mullite formation from gel. For adding ytterbia, mullite formation can take place at 1000 °C and almost single-phase mullite can be achieved at 1150 °C, which is a significantly lower temperature than mechanochemical method. This enhancement of mullite formation is also attributed to refinement of aluminum hydroxide-silica by gel. Furthermore, well-developed single-crystal mullite whiskers were produced from the gel powder instead of normal-shaped grains. The presence of YbO might have promoted the formation of nanosized Al₂O₃ particles, which then acted as a template leading to mullite whiskers at higher sintering temperature.