通过Al-AlN核壳结构中间体制备超洁净钢用Alon结合刚玉质耐火材料及其性能研究

The super clean steel is the core and foundation of the advanced manufacture industry of our country. One of the factors affecting its inclusion control is the refractory materials used for continuous casting in the refining period. Al2O3/C composite refractory materials are currently widely used. However, the carbon in the composite leads to contamination of the molten steel and the high temperature strength of the composite is limited. Therefore, it is necessary to cover research on its substitute. Owing to the advantages of carbon free and high temperature stability, Alon-corundum composite is an ideal refractory material for super clean steel production. But the high temperature and complexity of the synthesis procedure of Alon phases limits its research in refractory purposes..To solve the problems mentioned above, aluminum and corundum powders are used as raw materials in the project. First, a low temperature sintering process is designed to prepare an Al-AlN core-shell structure as the intermediate product, which greatly enhances the high temperature reactivity of aluminum powder. Then the aluminum and corundum powders are directly reacted by the high temperature sintering process. The Alon phases are formed in-situ in this step. By analyzing the factors affecting the crystal growth of Alon phases and the physical properties of the bulk material, a theoretical model is proposed to design, control and optimize the properties of Alon reinforced corundum refractory materials. Finally, the model is confirmed by the service evaluation of the refractory materials in the simulation experiments and the construction of the theoretical model is useful for future research on Alon reinforced refractory materials.

超洁净钢是我国先进制造业的核心与基础，其精炼后期连铸用耐火材料是其夹杂物控制的关键因素之一。目前广泛使用的铝碳质耐火材料存在增碳污染钢水、高温强度较低等问题，亟需研发可将其替代的新型耐火材料。Alon结合刚玉质耐火材料，具有无增碳及高温稳定性好等优点，可作为超洁净钢生产理想耐火材料，但Alon相合成温度较高、制备条件苛刻，因此目前对其在耐火材料领域的系统研究较少。.针对上述问题，本项目拟采用铝粉与刚玉颗粒为原料，首先通过低温烧结反应，制备具有核壳结构的Al-AlN反应中间体，从而大幅提高铝粉的高温反应活性；然后通过高温烧结反应促进铝粉与刚玉颗粒直接反应，进而原位生成Alon结合相材料。通过分析研究不同影响因素下Alon的晶体生长机制及其对材料整体性能的影响，建立相关理论模型，实现Alon结合刚玉质耐火材料体系的设计、调控与优化；最终结合模拟实验进行服役评价，验证理论模型，指导其理论研究。

本项目对通过Al-AlN核壳结构中间体制备超洁净钢用Alon结合刚玉质耐火材料及其性能进行了系统地实验研究与探索，取得了一些有益的结论与成果。通过在刚玉质体系中直接添加金属铝粉，经过低温-高温两步氮化烧成法，形成Al-AlN核壳结构中间体，合成Alon结合相，成功制备出高性能Alon结合刚玉质复合材料，解决了超洁净钢生产用刚玉质耐火材料的增碳问题。同时，探索出金属粉体添加量、反应及烧结温度、刚玉质材料组成等条件对Alon结合相结构与形貌的影响规律，分析Alon结合相的晶体生长方式；并通过总结Alon结合相与刚玉质基体的结合方式，得到Alon相提高刚玉质材料高温强度的原理，实现了Alon结合相结构与形貌的可控调节。进一步对所制备的Alon结合刚玉质复合材料的抗冲刷性能与抗热震稳定性进行了测试分析，建立了其优化设计模型；并在感应炉中模拟实际试验，对Alon结合刚玉质耐火材料进行服役评价。通过该项目的执行，制备出可用于超洁净钢生产的无增碳及高温稳定性好的Alon结合刚玉质复合材料，对于我国高品质钢生产水平的进步具有支撑和促进作用。