Corrosion resistance of tin coatings deposited by cold spraying

This article presents a study of corrosion resistance of tin and tin-based composite (Sn + Al2O3 and Sn + SiC) coatings deposited onto aluminium alloy substrates using the low-pressure cold spraying method. The samples were subjected to three different corrosion tests at a room temperature: (i) Kesternich test, (ii) a cyclic salt spray test and (iii) anodic polarisation test. The selected tests allowed extreme environment simulation typical for wide range of urban, industrial and marine service conditions. Evaluation of corrosion was carried out by analysing changes on the coating surface as well as in the microstructure. Additionally, the physicochemical tests were carried out using X-ray diffraction. XRD analysis clearly showed that abhurite Sn21O6Cl16(OH)(14) is the main corrosion product established after the polarisation measurements. Despite extreme corrosive conditions used in experiments all tin coatings showed minor corrosion changes which implies that abhurite serves as a buffer between the metal and the oxidising natural environment.