基于密度泛函理论的MgO水化反应机理研究及高效抗水化剂理论预测

Magnesia refractory is widely used in converter, ladle, tundish and other key parts, which is of significant importance for clean steel smelting. However, its main component of MgO is very easy to hydrate and this characteristic reduces its performance and limits its application range. At present, the mechanism of hydration of MgO at the molecular level and the mechanism of hydration resistance of anti-hydration agents are not clear, which restricts the solutions for hydration problem of MgO. This project intends to study the mechanism of hydration of MgO and the mechanism of hydration resistance of anti-hydration agents on the hydration of MgO based on density functional theory calculations, on the basis of which the high-performance anti-hydration agents are predicted and screened. The main research contents are as follows: 1) The mechanism of hydration of MgO at the molecular level will be studied, to explore the key factors to affect the hydration of MgO; 2)The mechanism of hydration resistance of anti-hydration agents will be investigated, to reveal the relationship between the structure characteristics of anti-hydration agents and their performances of hydration resistance; 3)Prediction theory model of high-performance anti-hydration agents will be established and experiments will be carried out to verify their performances. The results of this project could enhance the understanding of the mechanism of hydration of MgO and provide theoretical guidance for the design of novel high-performance anti-hydration agents, which is of significant application value for the development of magnesia refractory.

镁质耐火材料广泛应用于转炉、钢包、中间包等关键部位，对洁净钢冶炼具有重要的意义，但其主要成分MgO易水化的特性降低了其使用性能且限制了其应用范围。目前分子尺度上MgO的水化反应机理及抗水化剂对MgO水化反应的作用机制尚不明晰，制约了MgO水化问题的解决。本项目拟采用密度泛函理论计算研究MgO的水化反应机理及抗水化剂对MgO水化反应的作用机制，在此基础上预测并筛选高效抗水化剂。主要研究内容如下：1)分子尺度MgO水化反应机理研究，探索影响MgO水化反应的关键因素；2)抗水化剂的作用机制研究，揭示抗水化剂的结构特征与其抗水化性能之间的关系；3)高效抗水化剂预测理论模型的建立及实验验证。本项目研究结果可丰富对MgO水化反应机理的认识，为新型高效抗水化剂的设计及开发提供理论指导，对镁质耐火材料的发展具有重要的实用价值。

镁质耐火材料广泛应用于转炉、钢包、中间包等关键部位，对洁净钢冶炼具有重要的意义，但其主要成分MgO易水化的特性限制了其应用。目前分子尺度上MgO的水化反应机理及抗水化剂对MgO水化反应的作用机制尚不明晰，制约了MgO水化问题的解决。鉴于此，本项目采用密度泛函理论计算结合实验开展了如下研究：1）MgO水化的反应机理；2）抗水化剂对MgO水化的影响机制；3）抗水化剂对轻烧MgO粉体水化影响的验证。得到如下结论：1）MgO的表面缺陷和表面Mg配位数是影响其水化反应的关键因素，缺陷越多、Mg配位数越低，水化越容易；水化后形成的氢氧化镁层极易脱落，且H2O易在氢氧化镁层裂纹通道中扩散；故只有减少表面低配位数的Mg缺陷才能有效抑制MgO的水化。2）MgO尺寸是影响其水化反应的另一个重要因素，MgO团簇尺寸越小水化越容易，且水化团簇产物倾向于转变为氢氧化镁晶体。3）抗水化剂可与缺陷位的Mg配位成键，从而增加Mg的配位数和保护缺陷位，且抗水化剂分子含有的OH基团越多、分子量越大，抑制MgO水化的效果越好。4）轻烧MgO粉体经ISOBAM-104改性处理后，可以显著提高其抗水化性能，最佳处理条件为：ISOBAM-104加入量3wt%、热处理温度523K及热处理时间1h。本项目研究结果加深了对MgO水化反应机理的认识，可为新型高效抗水化剂的设计及开发提供理论指导，对镁质耐火材料的发展具有重要的实用价值。