Plasma Electrolytic Oxidation (PEO) Coatings on a Zirconium Alloy for Improved Wear and Corrosion Resistance

Abstract

Zr oxide coatings were deposited using plasma electrolytic oxidation (PEO) on Zr-2.5wt%Nb alloy, which is currently used for pressure tubes in the CANDU nuclear reactor. The effects of three processing factors: electrolyte concentration, current density, and terminal voltage on the microstructure and property of coatings were systematically investigated. The coating morphology was determined using scanning electron microscopy (SEM). Potentiodynamic polarization corrosion testing was used to exam the corrosion resistance of the coatings in a LiOH aqueous corrosion media. Pin-on-disc wear tests were performed under dry sliding test conditions in air coefficient of friction was calculated according to the tribological test. SEM was also used to characterize the wear tracks on the coatings. According to the research, recommendations are made as to processing parameters for the production of oxide coatings with improved wear and corrosion resistance.