Anodic Behaviour of Tin in Potassium Hydroxide Solution

Results of galvanostatic polarisation of tin anodes in potassium hydroxide solutions are reported.The orientation of the anode plays an important part in the observed behaviour. Permanent passivity occurs when the potential rises to that required for oxygen evolution from a film of stannic oxide, 50–100 Å, thick. At [KOH] up to and including 7 M, the prepassivation ‘active’ region of the potential–time behaviour conforms to a ‘solution-controlled’ reaction; at higher [KOH] anode films are formed with less and less dependence on mass transport in the electrolyte.Interpretations of the observed behaviours are given.