Abstract Alkali resistance and thermo-mechanical properties of the transition zone of cement rotary kilns refractories are the key factors affecting their service life. Calcium alumino-titanate (CAT) containing bauxite-SiC composites were prepared using bauxite, SiC, CAT, Guang Xi white clay, α-alumina, and metallic silicon powder as starting materials and Al(H2PO4)3 as the binder. The effects of the CAT particle size on the phase composition, microstructure, thermo-mechanical properties, and alkali resistance of the CAT-containing bauxite-SiC composites during firing were investigated. The results reveal that the CAT particle size strongly affects the composites’ microstructure and sintering densification. With decreasing particle size, the particle-particle and particle-matrix interfacial bonding deteriorates gradually. When CAT particles are added, the specimens show higher strength, refractoriness under load, and residual rupture strength than the specimens with fine CAT powders. Specimens with fine CAT powders show lower coefficient of thermal expansion compared to the specimens with CAT aggregates. The alkali attack test confirms that the bauxite-SiC composite refractories with CAT aggregates show better alkali resistance than those with CAT fine powder. According to the alkali mechanism, 1) K vapors penetrate the specimen through the open and connected pores and cracks, 2) K vapors react with anorthite and corundum to form kalsilite accompanied by the formation of a liquid phase and new cracks.

中文翻译：

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铝钛酸钙粒径对铝土矿-碳化硅复合耐火材料组织和性能的影响

摘要 水泥回转窑用耐火材料过渡区的耐碱性和热力学性能是影响其使用寿命的关键因素。以铝土矿、碳化硅、CAT、广西白土、α-氧化铝、金属硅粉为原料，Al(H2PO4)3为粘结剂，制备了含铝土矿-SiC复合材料的铝钛酸钙(CAT)。研究了 CAT 粒径对含 CAT 铝土矿-SiC 复合材料在烧成过程中的相组成、微观结构、热机械性能和耐碱性的影响。结果表明，CAT 粒径对复合材料的微观结构和烧结致密化有很大影响。随着粒径的减小，颗粒-颗粒和颗粒-基质的界面结合逐渐变差。当加入 CAT 颗粒时，试样的强度、载荷下耐火度和残余断裂强度比含有细 CAT 粉末的试样更高。与具有 CAT 聚集体的样品相比，具有细 CAT 粉末的样品显示出较低的热膨胀系数。碱侵蚀试验证实，采用CAT 骨料的铝土矿-SiC 复合耐火材料比采用CAT 细粉的铝土矿-SiC 复合耐火材料表现出更好的耐碱性。根据碱机理，1）钾蒸气通过开放和连通的孔隙和裂缝渗透试样，2）钾蒸气与钙长石和刚玉反应形成钙长石，伴随着液相和新裂缝的形成。与具有 CAT 聚集体的样品相比，具有细 CAT 粉末的样品显示出较低的热膨胀系数。碱侵蚀试验证实，采用CAT 骨料的铝土矿-SiC 复合耐火材料比采用CAT 细粉的铝土矿-SiC 复合耐火材料表现出更好的耐碱性。根据碱机理，1）钾蒸气通过开放和连通的孔隙和裂缝渗透试样，2）钾蒸气与钙长石和刚玉反应形成钙长石，伴随着液相和新裂缝的形成。与具有 CAT 聚集体的样品相比，具有细 CAT 粉末的样品显示出较低的热膨胀系数。碱侵蚀试验证实，采用CAT 骨料的铝土矿-SiC 复合耐火材料比采用CAT 细粉的铝土矿-SiC 复合耐火材料表现出更好的耐碱性。根据碱机理，1）钾蒸气通过开放和连通的孔隙和裂缝渗透试样，2）钾蒸气与钙长石和刚玉反应形成钙长石，伴随着液相和新裂缝的形成。