Fabrication of the nanoparticle incorporated PEO coating on commercially pure zirconium and its corrosion resistance

Surface modification of zirconium by the plasma electrolytic oxidation (PEO) with electrophoretic deposition (EPD) in a single step is reported. In this study, EPD is used to incorporate the Al2O3 or CeO2 or ZrO2 nanoparticles into the oxide layer produced over zirconium substrate by the PEO. Microstructural variation, corrosion resistance and scratch resistance of the coatings, fabricated by the PEO-EPD combined process, were investigated. The incorporation of nanoparticles significantly modified the surface morphology of the PEO coating. The incorporation of Al2O3 or CeO2 nanoparticle into the PEO coating induced a phase transformation from m-ZrO2 tot-ZrO2. The Potentiodynamic polarization test was performed in 0.6 M NaCl solution to evaluate the corrosion resistance of the fabricated coatings. Results showed that the nanoparticles incorporated PEO coating (PEO-EPD coating) significantly improved the corrosion resistance, compared to the PEO coating without nanoparticles addition. Among the three nanoparticles under this investigation, the CeO2 incorporated PEO coating provided the highest corrosion resistance and its icorr value is 103 times lower than the icorr value of the base PEO coating. The adhesion strength of the coating was evaluated by performing the scratch test and the PEO-EPD coatings showed higher scratch resistance than the PEO coating. Among the PEO-EPD coatings under this study, the CeO2 nanoparticle incorporated coating is considered to be the best coating for both corrosion resistance and scratch resistance.