Uniform Electrolytic Corrosion

Continuing to verify the principles of electrolytic corrosion, we turn from liquid amalgams to solid metals and to solutions with pH up to ca. 7, which is the overall range of ‘acid’ corrosion by superposition of anodic metal dissolution and cathodic hydrogen deposition by reduction of hydrogen ions rather than water. To exclude superposed oxygen reduction, the solution is assumed to be deaerated. The temperature is at 25°C or at some similar ambient value. The solution volume is supposed to be large, so that initial concentrations remain virtually constant during the course of the corrosion reaction, which is: Me + zH+ → Mez+ (z/2)H₂. The metal surface is thought to be bare, i.e. free of films such as air-formed oxide films, and free of layers of solid corrosion products such as oxides or hydroxides.