Effects of Cl-, UV, Ozone, and RH on Atmospheric Corrosion

In this study, the effects of several atmospheric parameters on atmospheric corrosion have been investigated.  The primary metal substrate has been Ag, but the results on other metals will also be mentioned.  Ozone and UV radiation have been found to have huge effects on the atmospheric corrosion of Ag.  In combination, with a high enough concentration of ozone, the two factors result in rapid attack.  Interestingly, with 4 ppm ozone, UV irradiation and a coating of nm-sized NaCl particles, the attack is highest for intermediate RH values near about 40%, with a vastly lower rate of attack (more than 10 times lower) at 90% RH, which is above the deliquescence point of NaCl.  The rate of corrosion is determined by a balance between the generation of reactive species and the transport of those species to the surface.