Influence of Inorganic Zinc Primer on Under-film Corrosion Simulation Parameters Based on Cellular Automaton

Abstract

Osawa et al. (2016) developed a two-dimensional cellular automaton (CA) for under-film corrosion analysis and succeeded in consistent analysis of coating film deterioration and corrosion depletion. In this study, epoxy coated steels with and without inorganic zinc primer were prepared, and the panels having one scribe were subjected to cyclic corrosion test (CCT). And the influence of inorganic zinc primer on CA parameters was investigated from the corrosion surface profiles. In the CCT, corrosion depth became unaffected by zinc as CCT test time passed. However, progress of corrosion in perpendicular direction from the scribe was greatly increased by absence of zinc. As a result of identifying the CA parameters, the increase of coating film deterioration acceleration rate A₀, the decrease of shielding duration T_S and the increase of acceleration factor of bare material f_bare were required by the specification change from zinc coating to no zinc coating. In order to understand the change of these parameters value, the mechanism of corrosion and blistering of epoxy coated steels with and without inorganic zinc primer was discussed. And the validity of difference in value of CA parameters with zinc coating and no zinc coating was shown based on the mechanism.