定電位電解におけるCu結晶(111)面の転位位置の溶解速度

Abstract

The (111) surface of copper crystal was etched anodically at constant potentials, 0, 20 and 40 mV vs SHE, in the solution containing 5 kmol·m−3 NaCl, 0.25 kmol·m−3 NaBr and 10−4 kmol·m−3 CuCl, and the dissolution rate at dislocation sites was determined through a measurement of three-dimensional size of the corresponding etch pits from optical and interference microphotographs taken at sucessive times. The width h and the depth d of the etch pits increased rapidly at an early stage of etching and then increased linearly with an increase of etching time t. It was to be added also that the etch pits grew larger when the applied potential was higher. However the side slope d/h of the etch pits decreased with an increase of t and tended to approach asymptotically a constant value. For a given potential, the anodic current density i increased slowly during the stage where the etch pit size, h and d, increased at a constant rate, and finally reached to a constant value. It was shown from the analysis of the above measurements that the i-t relation could be explained on the basis of dissolution processes during dislocation etch pitting.