Evaluation of increasing service life of epoxy zinc-rich coating on 3 wt.% Ni-advanced low-alloy steel in marine atmospheric environment

The addition of Ni element into steel to prolong the service life of coated steel was investigated in marine atmospheric environment by laboratory simulated accelerated experiment. The scanning electron microscope and electron probe micro-analysis combined with electrochemical impedance spectroscopy were used to characterize coated steel properties and examined the anti-corrosion performance. The results showed that 3 wt.% Ni-advanced steel (3Ni steel) substrate obviously delayed the failure time of coating compared to carbon steel, therefore prolonging the service life of coating on the steel. X-ray diffraction patterns for the corrosion products under the scratched coating on 3Ni steel exhibited that FeNi 2 O 4 and Fe 2 O 3 occurred in the corrosion product of 3Ni steel. It was also found that Ni element enriched in the product layer through analyzing the appearance and composition of corrosion products by electron probe micro-analysis. Chloride ions were blocked out of product by the enrichment of Ni element in rust layer.