Microstructure evolution during the heating process and its effect on the elastic properties of CAC-bonded alumina castables

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• 作者：Yulong Wang ; Xiangcheng Li ; ^{lixiangcheng@wust.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Boquan Zhu ; ^{zhuboquan@wust.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Pingan Chen
• 关键词：Calcium aluminate cement ; Refractory castables ; Microstructure evolution ; Elastic modulus
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：42
• 期：9
• 页码：11355-11362
• 全文大小：10122 K

文摘

In this paper, the alumina-based refractory castables were prepared using calcium aluminate cement (CAC) as binder. The phase composition and microstructural evolution of the castable samples during the heating process were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA), and thermal expansion analysis. The relationship between the microstructural characteristics of castables and the properties of elastic modulus was investigated. The results showed that, after the castables were cured at room temperature for 24 h and dried at 110 °C for 24 h, the main phases present after hydration were Al₂O₃, C₃AH₆, and AH₃. C₃AH₆ and AH₃ would be transformed into C₁₂A₇ and AlO(OH) or Al₂O₃, as temperature increased from 110 °C to 800 °C, the microcrack caused by decomposition of the hydrates will led to the lower values of both the elastic modulus and strength of the castable samples. From 900 °C to 1000 °C, CA was recrystallized through the reaction between C₁₂A₇ and A, resulting in an increase in elastic modulus and strength. Between 1100 °C and 1200 °C, CA₂ would be formed, which resulted in a volume expansion of the material and a slight increase in elastic modulus. Finally, the CA₆ phase was formed as the temperature increased to 1400 °C. The enhancement of the strength and elastic modulus of the castable samples could be attributed to their strong interlocking bonds between platelet CA₆ and matrix particles at high temperature.