Optical Microscopy Studies of Anodic Dissolution of Iron In Sulfuric and Hydrochloric Acid Solutions Available to Purchase

Microscopical observation was made during and after intensiostatic polarization of Armco iron electrodes. A correlation between etching degree and grain orientation was evident in sulfuric acid solutions. In hydrochloric acid solutions a smoothing at the inside of the grains, independently of their orientation and preferential corrosion at the boundaries occurred. It is suggested that in sulfuric acid the dissolution mechanism involving anion participation may be effective, while on hydrochloric solutions a competitive adsorption very probably takes place between Cl⁻ and OH⁻ or water molecules.