Initial stages of indoor atmospheric corrosion of electronics contact metals in humid tropical climate: tin and nickel

Samples of electrolytic tin and nickel have been exposed for 1 to 12 m in indoor environment, inside a box (rain sheltered cabinet), placed in tropical humid marine-urban climate, as a part of Gulf of Mexico. The corrosion aggressiveness of box has been classified as a very high corrosive, based on the monitored chlorides and SO2 deposition rates, and the Temperature/Relative Humidity air daily complex. The annual mass increasing of nickel is approximately twice higher than its values of lass loss (C). the relation between nickel mass loss or increasing and time of wetness (t) of metal surface is linear and does not obey the power equation C=A t''n, which has be found for tin. The SEM images reveal a localized corrosion on nickel and tin surfaces. XRD detects the formation of SnCl2.H2O as a corrosion product. Within the time on the tin surface appear black spots, considered as organic material. (Author) 26 refs