Potential distributions of
atmospheric corrosion caused by salt particle deposition were investigated using scanning Kelvin
probe technique.The results indicate that the changes in
potential distribution depended on the type of the salts and the relative humidity of the environment.At lower relative humidity,the potential distribution over the metal with salt particle deposition remained uniform.When relative humidity is higher than RHoss(Relative Humidity over Saturated Solution),however,the potentials around the salt particle deposition shifted negatively,forming a lower potential valley,and then the potentials outside the valley gradually moved positively,leading to volcano type of the heterogeneous potential distribution.This phenomenon can be observed on zinc and steel with the salt particle deposition such as sodium sulfate,sodium chloride and potassium chloride.The nonuniform potential distribution caused by the deposition of salt particle built-up anode and cathode which forms corrosion battery on the metal surface.Then,the
atmospheric corrosion was initiated and propagated.