Al_2O_3含量及热处理温度对Al_2O_3-SiO_2系浇注料抗铝液侵蚀性的影响

Influence of Al_2O_3 content and heat treatment temperature on corrosion resistance of Al_2O_3-SiO_2 castables to molten aluminum

采用坩埚法和浸泡法研究了不同Al2O3含量（质量分数分别为80%~85%、65%~70%、40%~45%、25%~30%）及不同温度（分别为110、800、1100和1 400℃）热处理后的Al2O3-SiO2系浇注料的抗铝液侵蚀性,借助电镜和能谱分析研究了被850℃铝液侵蚀后试样的显微结构。结果表明：（1）随着Al2O3含量的增加,Al2O3-SiO2系浇注料的抗铝液侵蚀性增强;（2）在1 100℃热处理后,浇注料的抗铝液侵蚀性最差;（3）铝液渗入浇注料内部后,铝液中的Al和Mg与浇注料中的石英和莫来石相发生反应,将SiO2还原成Si,Al和Mg则氧化成Al2O3和MgO,MgO进而与Al2O3反应生成尖晶石,破坏试样的结构;（4）对于Al2O3含量较高的Al2O3-SiO2浇注料,尖晶石富集层较致密,可阻止铝液继续向浇注料内部渗透。

Effects of alumina contents（80%-85%,65%-70%,40%-45%,and 25%-30%） and heat treatment temperatures（110,800,1 100,and 1 400 ℃,respectively） on corrosion resistance of Al2O3-SiO2 castables to molten aluminum were investigated by crucible method and immersion method.The microstructure of Al2O3-SiO2 castables corroded by molten aluminum at 850 ℃ was also analyzed by SEM and EDAX.The results show that：（1）with the increase of Al2O3 content,the corrosion resistance of Al2O3-SiO2 castables to molten aluminum grows better;（2）the corrosion resistance of Al2O3-SiO2 castables to molten aluminum heat treated at 1 100 ℃ is worst;（3）after molten aluminum penetrating into the castables,Al and Mg in molten aluminum react with quartz and mullite in castables reducing SiO2 to Si,and oxidizing Al and Mg into Al2O3 and MgO,and MgO further reacts with Al2O3 producing spinel,which results in structural damage of the specimens;（4）for Al2O3-SiO2 castables with higher Al2O3 content,the layer with rich spinel is dense and could prevent molten aluminum from penetration further.