Li2O对CaO-Al2O3基保护渣结晶性能的影响

摘要：高铝钢用新型CaO-Al2O3基连铸结晶器保护渣结晶性能较强，在连续浇铸过程中易出现润滑与传热功能协调不均的问题。基于此，针对新型CaO-Al2O3基保护渣，考察了典型助熔剂Li2O对保护渣析晶温度、析晶物相等性能的影响，并进行了相关结晶动力学分析。结果表明，提高Li2O含量可使保护渣的临界冷却速率和初始结晶温度呈现先降低后升高的趋势，当Li2O质量分数为4%时，保护渣结晶倾向最弱。随Li2O质量分数从0增至6%，保护渣的结晶孕育时间先延长后缩短。析晶物相由CaAl4O7+CaF2转变为CaAl4O7+CaF2+LiAlO2，Li2O的加入及其含量的提高促进了LiAlO2的析出。此外，随Li2O质量分数从0增至6%，保护渣结晶活化能先增大后减小，析晶过程受到的阻力先增强后减弱，与结晶性能的变化规律相吻合。

Effect of Li2O on crystallization properties of CaO-Al2O3 based mold fluxes

Abstract： The new CaOAl2O3 based mold powder for continuous casting of high aluminum steel has strong crystallinity, which is prone to the problem of uneven coordination of lubrication and heat transfer functions during continuous casting.Based on this, for the new CaO-Al2O3 based mold powder, the influence of typical flux Li2O on the crystallization temperature of mold powder and the properties of crystallized products was investigated, and the crystallization kinetics was analyzed. The results show that the critical cooling rate and initial crystallization temperature of mold powder decreased first and then increased with the increase of Li2O content. When the mass fraction of Li2O was 4%, the crystallization tendency of mold powder was the weakest. With Li2O mass fraction increased from 0 to 6%, the crystallization incubation time of mold powder firstly increases and then decreases. The crystallization phase changes from CaAl4O7+CaF2 to CaAl4O7+CaF2+LiAlO2. The addition of Li2O and the increase of its content promote the precipitation of LiAlO2. In addition, with Li2O mass fraction increased from 0 to 6%, the crystallization activation energy of mold powder firstly increases and then decreases, and the resistance to crystallization process first increases and then decreases, which is consistent with the change law of crystallization performance.