冶金、建材等高温过程工业广泛应用的方镁石-尖晶石耐火材料因材料内部晶界热失配及晶界相的熔点相对较低，导致高温强度和抗熔渣侵蚀性差的问题长期存在，对材料的晶界相进行重构是有效解决问题的基础。项目组前期工作发现，引入不同种类的稀土氧化物因离子半径和反应活性等不同，对材料的晶界相组成及性能的影响差别很大。重构低膨胀系数、高熔点晶界相可望有效解决此类材料高温性能较差的突出问题。项目拟深入研究不同性状的稀土氧化物对材料晶界相组成与结构的重构规律，阐明稀土掺杂晶界相形成及稀土离子在晶界相中赋存状态对材料显微结构的调控机理，建立稀土掺杂方镁石-尖晶石耐火材料中“晶界相、微结构与高温性能”的关联。项目提出稀土掺杂重构晶界相的新方法将为耐火材料微结构设计与调控提供理论依据，以实现碱性耐火材料的高性能化。

Magnesia-spinel composite refractory is widely used in metallurgy, building materials and other high temperature process industry. However, the problems of such as low high-temperature strength and poor performance of slag erosion resistance have existed for a long time. This is because of the thermal mismatch grain boundary in the materials and the relatively low melting point of grain boundary phase. The basis to solve this problem is the reconstruction of the grain boundary phase. The previous study of our project team indicated that different kinds of rare earth oxides introduced have obviously different effects on the composition of grain boundary phase and properties due to the different ionic radius and reactivity. The construction of grain boundary phase with low expansion coefficient and high melting point are expected to effectively solve the prominent problems of poorer high-temperature performance. In this project, the reconstruction law of rare earth oxides with different features on the composition and structure of grain boundary phase in the materials will be the further studied. The control mechanism of the formation of rare earth doped grain boundary phase and the occurrence state of rare earth ions in the grain boundary to the microstructures of the materials will be clarified. The correlations among the “grain boundary phase, microstructure and high-temperature properties” in the rare earth doped magnesia-spinel composite refractory will be established. The new method of reconstructing grain boundary phase through rare earth doping put forward in this project will provide theoretical basis for the design and control theories of refractory microstructure. This is beneficial to achieve basic refractory with high performance.