| Summary: | Coatings with thickness 40 to 150 μm were formed by plasma electrolytic oxidation (PEO) on the zirconium alloy Zr-1Nb (Zr-1% Nb) in the slurry electrolyte containing 9 g/L Na<sub>2</sub>SiO<sub>3</sub> 5H<sub>2</sub>O, 5 g/L Na(PH<sub>2</sub>O<sub>2</sub>) and 6 g/L submicron Y<sub>2</sub>O<sub>3</sub> yttria powder during 60 min under the AC electrical mode at current densities 20; 30 and 40 A/dm<sup>2</sup>. The surface morphology, structure, composition, and corrosion-protective ability of the formed coatings have been analyzed. At PEO current density 30 A/dm<sup>2</sup>, a predominantly tetragonal phase of zirconia was formed in coatings. Increasing the PEO current density up to 40 A/dm<sup>2</sup> promoted the formation of the coating surface layer containing submicron yttria particles. Electrochemical polarization studies in 0.5% LiOH solution showed that PEO coatings demonstrated high corrosion-protective ability. The dependence of the polarization currents on the PEO current density was found to be inconsequential.
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