Fabrication of rigid media tube filter bound with aluminum borate using Al₂O₃–B₂O₃–MgO frit for filtration of molten aluminum

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• 作者：Osamu Yamakawa ; Hiroshi Shirakawa ; Minoru Hashiba ; Osamu Sakurada
• 关键词：Aluminum borate ; 9Al₂O₃· ; 2B₂O₃ ; Rigid media tube filter ; RMF
• 刊名：Ceramics International
• 出版年：2010
• 出版时间：April 2010
• 年：2010
• 卷：36
• 期：3
• 页码：863-870
• 全文大小：1471 K

文摘

We performed a study of a tube filter binding agent for molten aluminum (rigid media tube filter, RMF). In this study, we examined the formation mechanism of aluminum borate (9Al₂O₃·2B₂O₃; 9A2B) from Al₂O₃–B₂O₃–MgO frit composition, which used MgO instead of CaO in the Al₂O₃–B₂O₃–CaO frit in our previous report. The results indicated that crystallization of 9A2B is easier in Al₂O₃–B₂O₃–MgO compared to Al₂O₃–B₂O₃–CaO, in that crystals are formed with only a heating process, and the amount of crystallization increases depending on the calcination temperature and the heat load over the retention time. A tube filter made of Al₂O₃–B₂O₃–MgO frit contained a larger amount of 9A2B crystals and therefore its strength did not deteriorate until a very high temperature of 1200 °C was reached, and its coefficient of thermal expansion was low. This is an advantageous property for RMF used under constraints and high temperatures. In addition, when the amount of 9A2B crystal formation increases, the wettability of molten aluminum decreases, and it becomes more difficult for molten aluminum to impregnate the filter material, but we found that corrosion resistance was high.