硝酸溶液中铝的电化学溶解行为

摘要

Aluminum is one of cladding materials for nuclear fuel.It is important to investi-gate the electrolytic dissolution of aluminum in nitric acid.The electrochemical impedance spectroscopy,polarization curve and cyclic voltammetry cure of anodic aluminum electrode in nitric acid under various conditions were collected.It turns out,under steady state,the thickness of the passivated film of aluminum decreases with temperature while increases with the concentration of aluminum nitrate.As the concentration of nitric acid increases,the thickness of the film decreases first and then increases.Under the polarization current, increasing of temperature,as well as the concentration of nitric acid and aluminum nitrate can facilitate the breakdown of the film,thus anodic dissolution occurs.The dissolution rate is only proportional to electric current,and a current efficiency of 0.4 g/(A · h)can be obtained.Our results provide theoretical foundations for developing electrolytic dissolution technology for aluminum-based nuclear fuel head end process.%铝常用作核燃料的包壳材料以及辐照靶件的基体材料。研究其电化学溶解行为对于开发新型铝基体首端溶解工艺具有重要意义。研究了铝在硝酸中的阳极溶解电化学行为，并测定一系列条件下铝阳极的电化学阻抗谱、极化曲线和循环伏安曲线。结果表明：在稳态时，铝表面形成钝化膜，钝化膜的厚度随硝酸浓度的升高先下降后升高，在硝酸浓度为4 mol/L 时厚度较薄；体系的温度升高、硝酸铝浓度下降都使钝化膜的厚度减小；在有极化电流作用下，升高温度、增大酸度以及增大硝酸铝浓度，都易于使膜击穿，从而实现阳极溶解；铝在硝酸中的溶解速率仅与电流强度有关，电解速率可达0.4 g/(A·h)。