Scanning Kelvin in probe for characterization of the metal-polymer interface.

The scanning Kelvin probe (SKP) has been used for the in situ determination of the distribution of the difference in Volta potential at metal-polymer interfaces. The measurements provided information about the structure of the double electric layer at the interface. The technique allows several interesting parameters to be determined, including the nature of the active chemical groups in the polymer that form the adhesive bonds with the metal, and the kinetics of the disbonding during water penetration at the metal-polymer interface. We found that it may be useful to monitor the change in Volta potential during wet-dry atmospheric transitions in order to evaluate the influence of surface pretreatment on the adhesion of the organic coating and on the rate of water diffusion through the organic coating. The effect of coating thickness on the Volts potential at the coating-metal interface was studied. The results are explained in term of the rate of diffusion of oxygen through the coating.