The role of salt particle deposition in the initiation and propagation of
atmospheric corrosion was studied using potential
distribution measurement.The results showed that the necessary condition for the
atmospheric corrosion initiation was the relative humidity higher than that over saturated solution of the salt particle,during which the salt particle absorbed water from the air and condensed electrolyte layer on the metal surface.At the same time,non-homogeneous potential
distribution with volcano type was formed around the place of salt deposition.The peak potential E p and valley potential E v changed drastically with rapid change of relative humidity,while the potential of the metal matrix remained.The difference of the peak potential and the valley potential E p- E v,the potential difference of the corrosion battery,increased rapidly with increasing the number of dry-wet cycles,which increased corrosion rate,too.It was also found out that the chemical distributions has close relationship with potential distribution on the metal surface with salt particle deposition.The model described the non-homogeneous potential distribution over the metal with salt deposition was proposed and the initiation and propagation of atmospheric corrosion caused by the salt deposition was elucidated,based on above findings.