Plasma electrolytic oxidation of Zircaloy-2 alloy in potassium hydroxide/sodium silicate electrolytes: The effect of silicate concentration

Abstract

This study mainly investigated the effects of silicate concentration at the range of (16g/L to 56g/L) on the plasma electrolytic oxidation of Zircaloy-2 in potassium hydroxide/sodium silicate electrolytes in detail, including the growth behavior, wear and corrosion resistance of as-obtained ZrO2/SiO2 alloyed coatings. It was found that the coating thickness increased continuously on increasing the silicate concentration in electrolyte. Besides, the amount of t-ZrO2 in the coatings increased with increase of silicate concentration in electrolyte, while the amount of m-ZrO2 decreased. Comparative studies have shown that the coatings formed in electrolyte with high silicate concentration possessed superior wear and corrosion performance, which could be ascribed to heavy silica deposition associated with the presence of t-ZrO2 stabilized by SiO2. The results may provide guidance for obtaining high performance of ZrO2/SiO2 alloyed coatings. Besides, it is believed that the presence of Si species in zirconia endows the coatings with enhanced bioactivity like bioactive glasses and ceramics coatings and we envision that the as-prepared ZrO2/SiO2 alloyed coatings have great potential for biological applications.