Rapid Assessment of Automotive Epoxy Primers By Electrochemical Techniques

By Julio J. Suay, M.T. Rodriguez, R. Izquierdo, A.H. Kudama, J.J. Saura

An epoxy primer commonly used in the automotive industry was applied cataphoretically (using different times and potentials) over metallic substrates, and was investigated by means of different techniques such as accelerated cathodic disbonding, EIS, and AC/DC/AC tests. The variables considered in this study were the metallic substrate (cold rolled steel and phosphatized cold rolled steel), the thickness (20 and 25 mm), and finally the deposition potential in the cataphoretic cell (140 V and 190 V).

The primer performed better when applied over phosphatized steel at the maximum thickness and when the lowest cataphoretic potential was used. Primer quality results obtained by the different techniques used in this study were quite similar and led to almost the same conclusions, although the AC/DC/AC and cathodic disbonding techniques provided results in less time than the EIS technique.