材料期刊网

含铝钢连铸时，钢水中的铝与保护渣中SiO2反应导致保护渣中Al2O3含量增加而SiO2含量减少，导致保护渣的热物理性能发生变化，从而影响了铸坯的质量。在以前的研究基础上使用X射线衍射仪(XRD)和差热分析仪(DTA)以及扫描电镜(SEM)研究了高铝保护渣固态渣膜的结晶行为与晶体显微结构的变化规律。结果表明，高铝保护渣中CaF2的析出主要是因为SiO2含量的减少和Al2O3含量的增加导致大量的Ca2+的功能由电荷补偿变为网络修饰体，温度降低时CaF2首先析出；随着保护渣中Al2O3含量的增加，在同一加热速率下析晶温度升高；当保护渣中Al2O3含量较少时，析出晶体为枪晶石(Ca4Si2O7F2)和少量的CaF2，当Al2O3含量大于5%(质量分数，下同)时，霞石(NaAlSiO4)进一步析出，且随着Al2O3含量的增加，析出晶体的尺寸减小。

The content of SiO2 deceases while Al2O3 increases in the mold flux on the casting of the steel containing high aluminium, which will cause the thermo-physical properties of the mold flux change, then influence the quality of the casting blank. On the base of the previous investigation, the crystallization behavior and the microstructure change with varying compositions of solid mold slag used in casting steels containing high Al was investigated through using differential thermal analysis (DTA) and X-ray diffraction technique (XRD), and the scanning electron microscope (SEM) techniques. The results indicate that the precipitation mechanism of CaF2 is because that the role of Ca2+ transforms from network charge compensation to networker modifiers with Al2O3 content increasing and the SiO2 decreasing, resulting in the precipitation of CaF2 firstly as the temperature decreases; the temperature of the crystallization is increasing at the same heating rate while the Al2O3 increasing; and the precipitated crystals transiting from single cuspidine phase contain a little CaF2 to nepheline appear and increase as the alumina content exceeds 5%, the size of the crystals is decreasing with the increasing of the alumina content.