Contact Deposition of Tin on Compact and Disperse Aluminum

The kinetics of the contact deposition of tin on aluminum from alkaline stannite solutions is studied by atomic absorption spectroscopy, gravimetry, titrimetry, X-ray diffractometry, and polarization diagrams. In the initial stage of the process, when regularities of non-steady-state diffusion are fulfilled, a large potential jump is observed. Therefore, to evaluate the rate of the contact exchange, it is suggested to use a correction factor equal to the ratio of the actual cathodic current density to the current density calculated from the polarization curve. On disperse aluminum, the rate is higher than that on compact aluminum because of different conditions for the diffusion of ions of tin(II) to the aluminum surface.