Abstract Calcium alumino-titanate (CAT) is a composite refractory material that exhibits a low thermal conductivity, high melting point, high refractoriness, low thermal expansion coefficient, and good thermal shock resistance. CAT-bauxite-SiC composites were prepared by using bauxite, CAT, SiC, α-Al2O3, metallic Si, and Guangxi white clay as starting materials and an Al(H2PO4)3 solution as a binder. Their densification behavior, phase changes, and microstructures were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermodynamic analysis. The results show that the bulk density initially increases and then decreases with temperature because of SiC oxidation and the formation of a liquid phase. In addition, the aggregation of corundum particles is enhanced at higher temperatures for bauxite grains, and excessively high temperatures cause abnormal growth of the corundum particles. Furthermore, the mullite whiskers present in the CAT grains begin to break through the surface of the liquid phase at firing temperatures above 1450 °C; these whiskers show perfect crystallization at 1600 °C. Finally, the quantity of Ca-rich (anorthite) regions around the SiC grains increase with temperature due to an increase in SiC oxidation and calcium ion diffusion.

中文翻译：

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铝钛酸钙-铝土矿-SiC复合耐火材料的烧结及显微组织表征

摘要 钛酸钙（CAT）是一种复合耐火材料，具有导热系数低、熔点高、耐火度高、热膨胀系数低、抗热震性好等特点。以铝土矿、CAT、SiC、α-Al2O3、金属Si和广西白粘土为起始原料，Al(H2PO4)3溶液为粘合剂，制备了CAT-铝土矿-SiC复合材料。通过 X 射线衍射 (XRD)、扫描电子显微镜 (SEM) 和热力学分析研究了它们的致密化行为、相变和微观结构。结果表明，由于 SiC 氧化和液相的形成，体积密度随温度先升高后降低。此外，铝土矿颗粒在较高温度下会增强刚玉颗粒的聚集，过高的温度会导致刚玉颗粒异常生长。此外，CAT 晶粒中的莫来石晶须在高于 1450 °C 的烧成温度下开始突破液相表面；这些晶须在 1600 °C 时显示出完美的结晶。最后，由于 SiC 氧化和钙离子扩散的增加​​，SiC 晶粒周围的富钙（钙长石）区域的数量随温度增加。