Electrochemical investigations of micro-droplets formed on metals during the deliquescence of salt particles in atmosphere

The formation of micro-droplets, 1-10 μm in diameter, were observed around the edge of main-droplet formed by the deliquescence of salt particles deposited on metals in atmosphere. The characteristics of the formation of micro-droplets were studied in a humidity-controlled chamber. The results showed that oxygen and relative humidity were the key variables for the formation of micro-droplets. Meanwhile, micro-droplets could only appear on the electropositive areas of metal surface based on the potential distributions with the scanning Kelvin probe. The electrochemical polarization results proved that the current established by the potential difference between the central and peripheral area of main-droplet was the true driving force for the formation of micro-droplets.