真空碳热还原制备Mg-Sr合金的反应热力学

介绍了真空碳热还原制备Mg-Sr合金新思路,研究了其还原反应的反应式、吉布斯自由能及临界还原温度。结果表明,真空碳热还原MgO,SrO的混合物可以得到Mg-Sr合金;其他因素不变的情况下,还原反应吉布斯自由能随反应温度的提高而减小,随系统气压的降低而减小,随反应生成的Sr,Mg混合蒸气中Sr摩尔分数的减小而减小;反应温度的提高、系统气压的降低和Sr摩尔分数的减小均有利于还原反应的进行;当系统气压为10 Pa,Sr摩尔分数为0.1时,临界反应温度为1353 K;相同系统气压下,碳热还原制备Mg-Sr合金的临界反应温度低于真空碳热炼锶、炼镁的临界温度,反应更易于进行;常规真空硅热还原制备金属镁(皮江法)的反应温度1473 K,气压13.3 Pa下,无论反应生成的Sr,Mg混合蒸气中Mg,Sr相对比例如何,真空碳热还原制备Mg-Sr合金的反应均具备热力学可行性。

Thermodynamics Approach for Preparation of Mg-Sr Alloy Using Vacuum Carbothermic Reduction

A new idea on the preparation of Mg-Sr alloys using vacuum carbothermic reduction was introduced;the reduction reaction equation,the Gibbs free energy and critical reaction temperature were studied.The results showed that Mg-Sr alloys could be obtained by vacuum carbothermic reduction the mixture of MgO and SrO.When other factors remain unchanged,with the reaction temperature raising,the system pressure reducing and the strontium′s mole fraction in Sr and Mg mixed steam decreasing,the Gibbs free energy of the reduction reaction reduced.The reaction temperature increased,system pressure reduction and strontium’s mole fraction reduction was in favor of reduction reactions.The critical reaction temperature was 1353 K when strontium’s mole fraction was 0.1 and the system pressure was 10 Pa.Under the same system pressure condition,its critical temperature was lower than carbothermic reduction producing metallic strontium or magnesium and the reaction tended to happen easily.Under the reaction temperature(1473 K) and system pressure(13.3 Pa) of conventional silicothermic reduction producing metallic magnesium(Pidgeon process) conditions,no matter what the relative proportions of magnesium and strontium from the steam generated in the reaction were,vacuum carbothermic reduction producing Mg-Sr alloys had the thermodynamics feasibility.