Electrochemical Studies of Atmospheric Corrosion

Atmospheric corrosion is usually considered to be of electrochemical nature. General discussions of the kinetics and mechanisms of atmospheric corrosion as understood at present can be found in the monographs by Rozenfeld ⁽¹⁾ and Barton ⁽²⁾. Some of the electrochemical characteristics of atmospheric corrosion have also been discussed by Kaesche ⁽³⁾. The fact that the electrochemical reactions occur under very thin layers of electrolyte is probably the reason that only very few detailed electrochemical studies of atmospheric corrosion phenomena have been reported. The conventional arrangement of small electrodes in large volume of electrolyte can obviously be used only after major modifications in thin layer electrolyte. Rozenfeld and his co-workers ^{(1, 4)} have reported experimental arrangements for electrochemical studies under thin electrolyte layers and have obtained polarization curves under layers of 0.1N NaCl as thin as 70μ (7 x 10^-3 cm). More recently Gladkikh and co-workers ⁽⁵⁾ have made studies of the electrochemical kinetics of zinc and iron corrosion under thin films of electrolytes (30-500μ). This limited number of electrochemical studies of atmospheric corrosion is in no relationship to the vast amount of literature available for corrosion studies in bulk electrolytes or for long-term outdoor exposure tests ⁽¹⁵⁾.