论文部分内容阅读
在NaF-NaCl-KCl-ScF_3熔盐体系中,采用铝热还原Sc_2O_3制备出Sc含量0.85%~4.20%的Al-Sc中间合金。引入金属间化合物Al3Sc作为铝热还原Sc_2O_3反应的生成物,热力学计算结果表明1 093~1 173K温度范围内反应可自发进行,且为放热反应。用等温饱和法测定Sc_2O_3在NaF-NaCl-KCl熔盐体系中的溶解度,结果表明,提高温度和NaF含量以及添加ScF_3均能提高Sc_2O_3在熔盐中的溶解度,而添加ScF_3的效果最显著。考察温度与ScF_3添加量对铝热还原过程中Sc回收率的影响。结果表明,温度升高,Sc回收率先提高后降低,在1 133K时达到最大;ScF_3添加量增加,Sc回收率亦先提高后降低,在3%ScF_3添加量时取得最大值。在1 133K、3%ScF_3添加量、保温1.5h条件下得到的Sc回收率最高可达86.06%。对制备的Al-Sc中间合金进行SEM与EDS分析,结果表明,Al-Sc中间合金中存在Al3Sc颗粒,呈方形或多边形,粒径较小,在基体中分布较分散。
In NaF-NaCl-KCl-ScF3 molten salt system, Al-Sc master alloy with Sc content of 0.85% -4.20% was prepared by aluminothermic reduction of Sc_2O_3. The introduction of the intermetallic compound Al3Sc as a product of the aluminothermic reduction of Sc_2O_3, the thermodynamic calculation results show that the reaction can spontaneously proceed in the temperature range of 1 093-1 173K and is exothermic. The solubility of Sc_2O_3 in NaF-NaCl-KCl molten salt system was determined by isothermal saturation method. The results showed that the addition of ScF_3 could increase the solubility of Sc_2O_3 in molten salt, while the addition of ScF_3 had the most significant effect. The effect of temperature and ScF_3 addition on the recovery of Sc during aluminum thermal reduction was investigated. The results showed that when the temperature was increased, the recovery rate of Sc increased first and then decreased, reaching the maximum at 1 133K; the amount of ScF_3 increased and the recovery rate of Sc increased at first and then decreased, and reached the maximum at 3% ScF_3 addition. At 1 133K, 3% ScF_3 addition, 1.5h incubation conditions, the maximum recovery of Sc reached 86.06%. SEM and EDS analysis of the prepared Al-Sc master alloy showed that Al3Sc particles were present in the Al-Sc master alloy in the shape of square or polygons with smaller particle size and more dispersed in the matrix.