Micro-droplets phenomenon and atmospheric corrosion - II. Electrochemical characteristics of the micro-droplets phenomenon

Micro-droplets phenomenon has a close relation with the electrochemical process of atmospheric corrosion. A volcano pattern of potential distribution with a potential valley in the center of main-droplet and a potential annular peak in the area covered with micro-droplets was observed by scanning Kelvin probe. The electrochemical polarization results proved that the spreading rate of micro-droplets increased linearly with the polarization current, and the corrosion current established by the potential difference between the central and peripheral area of main-droplet was the true driving force for the formation and spreading of micro-droplets.