Comparison of the Cathodic Protection of Epoxy Resin Coating/Zinc-Rich Coatings on Defective Areas under Atmospheric and Immersion Conditions: the Secondary Activation of Zinc Particles

The cathodic protection provided by epoxy coating/epoxy zinc-rich coatings on defective areas under atmospheric and immersion conditions was studied via a Q235 wire beam electrode (WBE), scanning electron microscopy, X-ray diffraction, and surface morphology analysis. The results showed that the cathodic protection processes under the two test conditions displayed significant differences. The effective protection time of the defective area under the atmospheric condition was 1.7 times that under the immersion condition. Compared with the immersion condition, zinc particles in zinc-rich coatings under the atmospheric condition exhibited higher cathodic protection efficiency. The possible activation mechanism of zinc particles under the two conditions was elucidated.