Atmospheric corrosion of tin coatings on H62 brass and T2 copper in an urban environment

To understand the difference of corrosion behavior between tin coatings on the copper and brass, the microstructure and atmospheric corrosion of the tin coatings on the H62 brass and T2 copper were compared by XRD, SEM/EDS and electrochemical measurements. The results showed that the preferred planes structure of the tin coatings were (101) and (1 1 2). More SiO(2 )inclusions existed in the tin coating on the brass than on the copper. In the atmospheric environment, the corrosion rates of tin coatings on the brass and copper were 1.427 and 0.578 mu m.y(-1), respectively. The local corrosion sensitivity of the tin coatings on the brass was higher than that on the copper. No matter on the copper or the brass, the local corrosion sensitivity and R of the skyward surface of the tin coatings were greater than that of the earthward surface. The preferential corrosion of the (101) oriented crystal particles was the dominated reason for the higher corrosion sensitivity of the tin coatings. The preferential wetting, the more suspended particles and the intense scouring of rainwater affected the corrosion process of the tin coating as well.

Automated summary

By comparing the microstructure and atmospheric corrosion of tin coatings on H62 brass and T2 copper, it was found that the tin coating on brass had more inclusions and higher local corrosion sensitivity. The local corrosion sensitivity and R value of the tin coatings on both copper and brass were higher on the skyward surface than on the earthward surface. The preferential corrosion of (101) oriented crystal particles was the main reason for the higher corrosion sensitivity of the tin coatings, and preferential wetting, suspended particles, and rainwater scouring also influenced the corrosion process of the tin coating.