The structure and corrosion barrier performance of nanocrystalline zirconia electrodeposited coating

Zirconia (ZrO2) with the thickness of about 1.5 μm were prepared onto mechanically polished and electrochemically prepared surfaces of 316L stainless steel by direct and pulse current electrodeposition followed by annealing. The ZrO2 coatings were nanocrystalline with a tetragonal crystallographic structure. The coatings produced by direct current showed a heterogeneous structure in “cracked-mud” appearance. Pulse current produced a more uniform and dense coating with a strong mechanical barrier property. It also revealed a passive behavior on the Tafel polarization plot. The ZrO2 coatings produced on electrochemically prepared surfaces showed a very small passive region on Tafel polarization curves.