Abstract: The effect of quartz, wollastonite, fluorite and soda-ash on melting point, viscosity, crystallization temperature and critical cooling rate of mold powder has been studied by mold powder series (/% ：29-39 cement grog, 8 borax ,16-24 quartz, 11-19 wollastonite, 8-16 fluorite, 10-18 soda-ash) by different compounding mineral crude materials in lab. Test results show that with increasing basic mineral crude materials quartz and wollastonite content the melting point and viscosity of mold powder increase, and the effect of quartz on melting point and viscosity of mold powder is obviously more than that of wollastonite ； with increasing flux mineral crude materials fluorite and soda-ash, the melting point and viscosity of mold powder decrease, the effect of fluorite on decreasing viscosity is obvious and the effect of soda-ash on decreasing melting point is relatively larger ； with increasing the content of quartz, wollastonite and soda-ash the critical cooling rate of mold powder decreases, the crystallization temperature of mold powder decreases and the capacity of crystallization is weak； but with increasing quartz content the critical cooling rate increases, the crystallization temperature increases ,it shows that quartz has the effect to improve crystallization of mold powder. Finally it is obtained the optimum ingredient of mold powder for peritectic steel casting is (/ % )：37 cement grog, 8 borax, 20 quartz, 15 wollastonite, 10 fluorite and 10 soda-ash.

Key words: Mold Powder, Mineral Crude Materials, Melting Point, Viscosity, Crystallization Temperature, Critical Cooling Rate

摘要： 实验室内通过配比不同矿物原料的保护渣系（/%:29~39水泥熟料,8硼砂,16~24石英,11~19硅灰石,8~16萤石,10~18纯碱）研究石英、硅灰石、萤石、纯碱对保护渣熔点、黏度、结晶温度、临界冷却速度的影响。试验结果表明,随着基料矿物石英、硅灰石含量增加,保护渣熔点、黏度增加,石英对熔点和黏度的影响明显大于硅灰石;随熔剂矿物萤石、纯碱含量增加,保护渣的熔点和黏度降低,萤石对降低黏度的作用显著,纯碱对降低熔点的作用相对较大;石英、硅灰石、纯碱含量增加,保护渣临界冷却速度减小,结晶温度降低,结晶能力减弱;相反,萤石含量增加,保护渣临界冷却速度却增大,结晶温度升高,说明萤石具有促进保护渣结晶的作用。最终得出包晶钢板坯连铸最佳保护渣配比为（/%）:37水泥熟料,8硼砂,20石英砂,15硅灰石,10萤石和10纯碱。

关键词: 保护渣, 矿物原料, 熔点, 黏度, 结晶温度, 临界冷却速度