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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。
When the aluminum-containing steel is continuously cast, the reaction between aluminum in the molten steel and the SiO2 in the mold powder leads to the increase of the Al2O3 content in the mold powder and the decrease of the SiO2 content, which leads to the change of the thermal physical properties of the mold powder, thereby affecting the quality of the slab. Based on the previous studies, X-ray diffraction (XRD) and differential thermal analysis (DTA) and scanning electron microscopy (SEM) were used to study the variation of the crystalline behavior and microstructure of the solid aluminum slag. The results show that the CaF2 precipitation in the high aluminum protective slag is mainly due to the decrease of SiO2 content and the increase of Al2O3 content, which leads to the function of a large amount of Ca2 + from charge compensation to network modification. When the temperature decreases, CaF2 precipitates first. When the content of Al2O3 is less than 5% (Ca4Si2O7F2) and a small amount of CaF2, when the content of Al2O3 is more than 5% (mass fraction, The same below), nepheline (NaAlSiO4) further precipitated, and with the increase of Al2O3 content, precipitated crystals decreased in size.