Electrochemical evaluation of defect growth in primers applied on aluminium alloy 2024T3

In the present work, the protective properties of inhibitive pigments in two epoxy-primers against corrosion of the aluminium alloy 2024T3 in marine atmosphere were investigated, the first containing SrCrO4 and the second one Zn3(PO4)2. Potentiostatic polarisation and electride impedance measurements were utilized to evaluate both the spontaneous onset of defects on coated samples and the prapagation of a small artificial defect of known dimension applied since the beginning of the test on each sample, during 24 months of exposure to the marine atmosphere. These techniques enabled a quantitative evaluation of the protective efficiency of the two primers to be made, and for the effects of the surface pre-treatments of the metallic substrate to be investigated.