HIGH RATE ANODIC DISSOLUTION OF COPPER

The present work demonstrates the feasibility of studying an electrochemical process proceeding at a current density of many amperes per square centimeter under controlled hydrodynamic conditions. A rectangular flow channel cell operated under fully developed turbulent flow conditions has been found to be well suited for this investigation. A study of copper dissolution in KNO//3 and K//2SO//4 solutions has shown two distinct dissolution modes. Active dissolution resulting in etched surfaces occurred at relatively low overpotentials. Observed dissolution rates were well within the limits estimated from knowm mass transfer relations for the transport of cupricons away from the surface. Transpassive dissolution proceeded at higher anode potentials, leading to pitting and brightening. Current densities applied during transpassive dissolution were up to 10 times higher than the minimum current density leading to passivation.