Mullite-corundum ceramics with various mullite crystal structures were prepared by incorporating Fe₂O₃ into the ceramic powder. The impact of the Fe₂O₃ content on the morphological evolution and formation mechanism of mullite crystals, as well as the thermal shock resistance and enhancement mechanism of the ceramic, were investigated. The results show that Fe₂O₃ facilitates the formation of a low-viscosity liquid phase and enhances the dissolution-precipitation mass transfer rate at the liquid/solid interface, forming an iron-containing mullite solid solution, inducing lattice distortion, and accelerating the c-axis growth of mullite crystals. With increasing Fe₂O₃ content, the mullite crystals changed from short columnar to elongated structures, and the grains were gradually interwoven with each other to form a network structure. The intergranular fracture mode of the sample was transformed into a mixed mode of transgranular and intergranular fractures. The maximum flexural strength was 83.60 MPa, with a retention rate of 94.65%, indicating improved strength and thermal shock stability.

中文翻译：

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铁掺杂莫来石刚玉陶瓷的微观结构演变和热冲击行为

通过将 Fe ₂ O ₃ 掺入陶瓷粉末中，制备了具有各种莫来石晶体结构的莫来石-刚玉陶瓷。研究了 Fe ₂ O ₃ 含量对莫来石晶体形貌演变和形成机制的影响，以及陶瓷的抗热震性和增强机制。结果表明，Fe ₂ O ₃ 有利于低粘度液相的形成，提高了液/固界面处的溶解-沉淀传质速率，形成含铁莫来石固溶体，诱导晶格畸变，加速莫来石晶体的 c 轴生长。随着 Fe ₂ O ₃ 含量的增加，莫来石晶体由短柱状变为细长状结构，晶粒逐渐相互交织形成网状结构。样品的晶间断裂模式转变为跨晶和晶间断裂的混合模式。最大弯曲强度为 83.60 MPa，保持率为 94.65%，表明强度和热震稳定性有所提高。