Phenomenon of micro-droplets formation on metals during the deliquescence of salt particles in atmosphere

Abstract

The characteristics of the formation of micro-droplets were investigated in a humidity-controlled chamber. The results showed that the micro-droplets formation had a close relation with the atmospheric corrosion of metal based on the pH and potential distributions of micro-droplets. Micro-droplets could only appear on high potential area in a corrosive combination of metals and salt particles. Meanwhile, a high value of pH was found in the areas covered with micro-droplets. The formation of micro-droplets needed two premises, one was that the relative humidity should be over the saturated relative humidity of main-droplet, the other was that the metal substrate could be eroded under the main-droplet.