三价铬离子电化学还原过程研究

STUDY OF ELECTROCHEMICAL REDUCTION PROCESSOF TRIVALENT CHROMIUM ION

通过循环伏安测量研究了简单三价铬盐溶液和三价铬镀液中Ｃｒ３＋的整个电化学还原过程．实验和计算结果表明，该过程分２步进行．第１步是Ｃｒ３＋还原为Ｃｒ２＋的单电子准可逆反应，具有催化反应特征．第２步是Ｃｒ２＋还原为金属铬的不可逆反应．在镀液体系中，Ｃｒ３＋的还原由简单盐溶液中的单一水合离子放电转变为多重络离子放电．

The complete electrochemical reduction process in a simple solution of trivalent chromium and in a trivalent chromium plating bath is investigated by a cyclic voltammetric measurement method.The test data from the laboratory test and the calculated data have shown that the reduction process can be divided into two steps.In the first step,Cr 3+ is reduced into Cr 2+ ,which is a quasi reversible reaction of a single electron,which is characterized by catalytic reaction.In the second step,Cr 2+ is reduced into a metal chromium,which is an irreversible reaction.In the plating bath system,reduction of Cr 3+ is a process which changes from discharging of a single hydration ion in a simple solution of trivalent chromium into discharging of multiple complex ions.