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在氩气气氛下钼丝炉内,用密封电融氧化镁坩埚直接合成Ca_3As_2-CaC_2渣。在1520、1560和1600℃进行了钢液中钙、砷平衡的研究。用扫描电镜能谱定量分析鉴定了平衡产物为Ca_3As_2。根据化学反应式: 3(CaC_2)+2[As]=(Ca_3As_2)+6[C] lgK=lga_(Ca_3As_2)-3lga_(CaC_2)+lgR;R=a_C~6/a_A~2。通过实验测定R值,再应用变通的Gibbs-Duhem方程求二元系各组元活度的方法,得到1520℃时, Ca_3As_2在二元渣系中的活度为: 实验测得1520℃时, 3[Ca]+2[As]=(Ca_3As_2) lgK’=9.867-3.00{2[％Ca]+1.60[％As]} 其中可以证明,该温度下lgK=9.867,(?)=-3.00。1560、1600℃的平衡实验是在Ca_3As_2饱和的二元渣系中进行的,分别测得lgK=9.754和9.299。回归处理后得到: 3[Ca]+2[As]=(Ca_3As_2) lgK=23780/T-3.339 进而算得: 3Ca_((g))+As_(2(g))=Ca_3As_2 ΔG°=-702300+130.46T,J
In an argon atmosphere, a molybdenum wire furnace was used to directly synthesize Ca_3As_2-CaC_2 slag with a fused magnesia crucible. The equilibrium of calcium and arsenic in molten steel was investigated at 1520, 1560 and 1600 ℃. Quantitative analysis by scanning electron microscopy identified the equilibrium product as Ca_3As_2. According to the chemical reaction formula: 3 (CaC_2) +2 [As] = (Ca_3As_2) +6 [C] lgK = lga_ (Ca_3As_2) -3lga_ (CaC_2) + lgR; R = a_C ~ 6 / a_A ~ 2. By experimentally determining the R value and then using the modified Gibbs-Duhem equation to find the activity of each element in the binary system, the activity of Ca_3As_2 in the binary slag system obtained at 1520 ° C is as follows: When the temperature is 1520 ° C, 3 [Ca] +2 [As] = (Ca_3As_2) lgK ’= 9.867-3.00 {2 [% Ca] +1.60 [% As]} where it can be shown that at this temperature lgK = 9.867, (?) = -3.00. Equilibrium experiments at 1560 and 1600 ° C were carried out in a binary slag system saturated with Ca_3As_2 with lgK = 9.754 and 9.299, respectively. After the regression process, we get: 3 [Ca] +2 [As] = (Ca_3As_2) lgK = 23780 / T-3.339 Further calculation: 3Ca_ (g) + As_ (2) = Ca_3As_2 ΔG ° = -702300 + 130.46T, J.