LAUSR

Hafnium dioxide (HfO2) has a wide bandgap and high dielectric constant. We prepared ceramic coatings on Ti6Al4V alloys via plasma electrolytic oxidation (PEO) in an electrolyte with HfO2 particles. The influence of the HfO2 particles on the microstructure, phase composition, elemental distribution, and corrosion resistance of the PEO coatings was systematically investigated. The results showed that the addition of HfO2 increased the oxidation voltage (from 462 to 472 V) and promoted the microarc sintering reaction so that the thickness and hardness of the resulting PEO coating increased. Moreover, the quantity of the micropores on the coating surface caused by the discharge decreased after adding the HfO2 particles. The X-ray diffraction patterns confirmed that the HfO2 particles were incorporated into the coating by remelting and sintering the microarc. Furthermore, the corrosion resistance of the PEO coating was remarkably increased after introducing HfO2, which was attributed to the increase in the electrode potential and the densification of the coating structure.