Effect of anodic polarization on the process of tantalum anodic dissolution

Considered is the effect of anodic polarization on the process of electrochemical polishing of tantalum. The increase of anodic polarization of tantalum electrode causes the increase of the metal passivity and the decrease of its dissolution rate. In view of this fact studied is the effect of electrolyte composition, concentration and nature of surfactant admixture, stirring and electrolyte temperature on the value of anodic polarization. The results of studies allow one to recommend an electrolyte of the following composition: hydrofluoric acid of 8.15%, sulfuric acid of 40-60%. surfactant (sulfoponate, secondary alkylsulfates) of 2-5 g/l, foam suppressor (PMS-200A, A-154) of 0.01-0.1 g/l, water. Conditions of polishing are as follows: current density of 20-100 A/dm2, temperature of 70-90 deg C, time of exposure of 3-5 min