THE EFFECT OF MICRO-DROPLETS FORMATION CAUSED BY THE DELIQUESCENCE OF THE DEPOSITED SALT PARTICLE ON ATMOSPHERIC CORROSION OF METALS

摘要

Salt particle deliquescence on metal surface is one of the main causes for atmospheric corrosion initiation. It is observed recently that after a salt particle deliquesces and forms a droplet, a large amount of micro-droplets formed and grow-up surround the primary droplet. This work studied the characteristic of micro-droplets formation and its relation to atmospheric corrosion initiation. It is found out that micro-droplets formation rested with the RH and the corrosiveness of the primary-droplet solution to the metal, and micro-droplet zone exhibited cathodic character with higher pH and positive potential. The results revealed that micro-droplet formation depends on the RH which should be higher than that of over saturated solution of the primary droplet, at the first, and the corrosiveness of the primary-droplet solution to the metal, at the second. In addition, it is confirmed that the mocro-droplet can be formed only on cathodic zone around the primary droplet.