Effect of sealing treatment on corrosion behaviours of arc sprayed zinc coatings

In this work, a simulated corrosion electrolyte was employed in order to assess the effect of sealing treatment on the corrosion resistance of arc sprayed zinc coatings in atmospheric environment. The microstructures and corrosion behaviours of unsealed and sealed coatings had been studied using scanning electron microscopy and electrochemical testing. Scanning electron microscopy observations revealed that the unsealed coating consisted of an outer coarse layer and an inner impact layer. As for the sealed coating, the sealing agent not only covered the surface but also permeated into the original microdefects on the outer coarse layer of the as sprayed coating. The results of electrochemical testing and corrosion morphology observations indicated that the corrosion resistance of the sealed coating was enhanced a great extent due to the blocking and shielding effect of the sealing layer.