Plasma electrolytic oxidation and corrosion protection of Zircaloy-4

The compositions and morphologies of coatings formed by plasma electrolytic oxidation (PEO) on Zircaloy-4 in silicate electrolyte, using an AC current regime, have been determined for a range of formation times. The coatings consist of zirconia with incorporated silicon species, with the distributions of coating species related to the types of discharges. Potentiodynamic polarization in 6 M nitric acid at 100 °C indicated that the corrosion resistance is mainly provided by the thin barrier layer next to the substrate.