Corrosion and Passivation Behaviors of Tin in Aqueous Solutions of Different pH

Abstract

Corrosion and passivation of tin at various pH have been investigated using different electrochemical techniques. Tin is a little active metal even if it is less than the hydrogen equilibrium compared to its domain stability set. Tin acts as Sn(II) via the active zone, so it corrodes with evolving H2 gas in an acidic medium. In passive areas, Sn(IV) is oxidized to produce an inclusive variety of passivity outstanding to the permanence of either Sn(OH)4 and/or SnO2 anodic surface of tin(IV), which is stable to lower pH. Tin's active dissolution requires one anodic peak and strengthens with rising acid electrolyte. The cathodic curve shows one cathodic peak consistent with passive tin layer reduction. Adding any polyethylene glycols to a solution of citric acid reduces the existing anodic peak density and changes its peak potential in the negative direction. Those changes depend on the added polyethylene glycol concentration and molecular weight. In an acidic environment comprised chromic, phosphoric, and hydrochloric acids, amorphous SnO nanotubes were manufactured using Sn nanowires (NW) electrodeposited to anodic aluminum oxide frameworks by a local degradation process. The phosphoric acid disintegrates the base initially, while also chromic acid generates an oxide layer of SnO at the NW level. Finally, Sn NWs with 10 μm in length and 30 nm in diameter are completely converted into the polycrystalline SnO form by crystallization of the amorphous nanotubes after heat treatment with rough morphology of the earth.