( 1.天津大学 材料科学与工程学院，天津 300072;
2. 江苏科技大学 材料科学与工程学院， 镇江 212003)
摘 要: 针对焊接熔渣分子理论及离子理论存在的局限，基于冶金界近年来提出的熔渣共存理论， 结合MgO-CaO-SiO2高温三元相图确定的结构单元， 利用质量平衡原理建立了MgO-CaO-SiO2三元熔渣离子活度热力学计算模型， 并借助于Matlab计算工具进行数值求解。 计算结果表明，该模型可同时兼顾熔渣的分子理论和离子理论， 离子活度随碱度的变化与碱度理论及直流焊接冶金电化学实验结果一致， 在焊接化学冶金定量研究方面显示出良好的应用前景。
关键字: 焊接熔渣；离子活度； 热力学； 碱度
（ 1.School of Materials Science and Engineering,
Tianjin University, Tianjin 300072 , China;
2. School of Materials Science and Engineering,
Jiangsu University of Science and Technology,
Zhenjang 212003, China）
Abstract: To counter its own limitation of either molecular theory or ion theory about welding molten slag, based on coexist theory of molten slag in metallurgy circle in recent years and combined with MgO-CaO-SiO2 ternary diagram at high temperature, a thermodynamic calculating model of ion activity was proposed for MgO-CaO-SiO2 ternary phase molten slag by applying quality equilibrium principle. The numerical solve was carried out with the help of matlab software tool. The calculating result shows that this model may give consideration to both molecular theory and ion theory of molten slag and the tendency of ion activity varying with basicity index is in accordance with basicity index theory and also the result of metallurgy electrochemical experiment in direct current welding. This appears good applying foreground in quantitative analysis of welding chemical metallurgy.
Key words: welding molten slag; ion activity; thermodynamic; basicity index
