On the Anodic Behavior of Copper in Aqueous Solutions of Orthophosphoric Acid

Abstract

A copper surface anodically etched in aqueous solutions of orthophosphoric acid becomes as bright as though it had been polished, if voltage and current density are kept within definite limits. If properly controlled, anodic etching will reveal the crystalline structure of the metal. The phenomenon seems to be based on the passivation of the anode and is a function of concentration polarization. The anodic etch method has been applied to metal sections intended for metallographic examination; excellent results were obtained. As compared with the usual polishing method, the anodic has the advantage of being much more rapid and less expensive.