真空碳热还原制备Mg-Li合金热力学分析

The thermodynamic analysis of Mg-Li alloys preparation by vacuum carbothermic reduction method

摘要:

提出了真空碳热还原制备Mg-Li合金的新思路，并对还原反应进行了热力学分析，研究了还原反应的反应式、吉布斯自由能及临界还原温度。结果表明：真空碳热还原制备Mg-Li合金具备热力学可行性，且其吉布斯自由能随真空度和反应温度的升高而降低；相同真空度下，该反应的临界反应温度低于真空碳热还原制备金属Mg、金属Li的临界温度，反应更容易进行；当真空度为10Pa，Li2O的相对比例为0.1时，真空碳热还原制备Mg-Li合金的临界反应温度为1345K；在常规皮江法(真空硅热还原法)制镁的反应条件下，不论反应物料中MgO、Li2O相对比例为多少，真空碳热还原制备Mg-Li合金均具有热力学可行性。

Abstract:

A new method of preparing Mg-Li alloys by vacuum carbothemic reduction is proposed. The thermodynamics of the reduction reactions were analyzed and the equations of the reduction reactions, the Gibbs free energy and critical temperature of reactions also have been studied. The results show that vacuum carbothermic reduction producing Mg-Li alloys had the thermodynamics feasibility. Under the condition of the other factors unchanged, with the increase of vacuum degree and reaction temperature, the Gibbs free energy of reduction reaction reduced. Under the same vacuum degree condition, the critical temperature of vacuum carbothermic reduction producing Mg-Li alloys was lower than producing metallic Mg or metallic Li, and reaction was more easily. When the vacuum degree was 10Pa and the relative proportion of Li2O was 0.1, the critical temperature of vacuum carbothermic reduction producing Mg-Li alloys was 1345K. Under the reaction temperature (about 1473K) and vacuum degree (about 13.3Pa) of conventional Pidgeon process(producing metallic magnesium by vacuum silicothermic reduction) conditions, no matter what the relative proportions of magnesium oxide and lithium oxide in the hybrid system, vacuum carbothermic reduction producing Mg-Li alloys had the thermodynamics feasibility.