NaF-NaCl-KCl熔盐体系中铝热还原法制备Al-Sc合金

Preparation of Al-Sc Alloys by Aluminum Thermite Reaction in NaF-NaCl-KCl Melt

在Na F-NaCl-KCl熔盐体系熔融状态下,用铝热法还原氟化钪制备出钪含量2.37%~8.13%的铝钪合金。引入金属间化合物Al3Sc作为生成物对反应式进行修正,热力学计算结果表明,该反应在1033 K温度下可以进行,且反应焓变为负值,反应放热。设计正交实验分别考察保温温度、保温时间与钪投入量三个因素对钪回收率的影响;设计单因素实验考察保温温度对钪回收率的影响。结果显示,在1033 K、钪投入量3%、保温1 h条件下得到最高钪回收率为94.13%。保温温度是钪回收率的主要影响因素,回收率随温度升高先上升后降低。钪投入量是钪回收率的次要影响因素,回收率随投入量增加而降低。保温时间对钪回收率的影响最小,延长保温时间能少量提高回收率,超过1h后回收率不再上升。

Al- Sc alloys with 2. 37% ～ 8. 13% Sc content were prepared by aluminum thermite reaction with Sc F3 in NaF-NaCl-KCl molten salt system. Introducing the Al3 Sc intermetallic as a product to amend the formula,the thermodynamic calculation at 1033 K suggested that Al was able to react with Sc F3 in the condition. The negative standard enthalpy of the reaction at 1033 K revealed that the reaction was exothermal. A series of orthogonal experiments including three factors which were reaction temperature,reaction period and feed capacity of Sc were arranged for the purpose of revealing the influence of the factors on recovery of Sc. Single factor experiments were also employed to inspect the effect of reaction temperature on the recovery independently. The results show that the maximum recovery,which is high up to 94. 13%,is obtained at 1033 K with 3% feed capacity for 1 hour reaction period. The results also reveal that reaction temperature is the major influence on recovery,which rises first then fall with temperature elevating. Feed capacity of Sc is the secondary influence on recovery,which falls with its increasing. Reaction period is the least influence on recovery,which can be promoted in certain degree by reaction period extending,but it hardly works for more than 1 hour.