Anodic Behavior of Mild Steel in NaCIO at High Current Densities

The IR-free anode potential and the current efficiency were studied for the electrochemical machining of mild steel in NaC103. The results show that an electronically conductive oxide film is present in the low current density region where the current is consumed in oxygen generation. With increas-ing current density, the film begins to break up with the formation of pits in the film. The film finally disappears in the high current density region where the metal dissolution takes place with a current efficiency greater than 100% and the metal surface is polished due to the presence of a precipitated salt layer with high ionic conductivity. In order to compete with conventional methods of metal removal, it is important for an electrochemical machining (ECM) process to provide the workpiece with good dimensional control and surface finish. For ECM of steels, NaC108 has been found to be superio