Effects of the Addition of Calcium Acetate into Silicate-Based Electrolytes on the Properties of MAO Coatings Produced on Zirconium

Abstract

Zirconium (Zr) is a potential implant material due to its excellent biocompatibility and low elastic modulus for biomedical applications. Its poor bioactivity, however, limits its use as biomaterials. In this study, microarc oxidation which is a plasma-electrochemical based process was applied to produce oxide coatings on pure zirconium. The coating processes were conducted in different electrolytes containing sodium silicate and varying amounts of calcium acetate tetrahydrate (CA) for 30 min to investigate the effect of the introduction of CA into the electrolyte solution on the morphology and chemical composition of the fabricated coatings. It was found that the coatings consisted of monoclinic-ZrO2 and tetragonal-ZrO2 phases. The amount of the tetragonal-ZrO2 phase increased with the increasing CA concentration in the electrolyte. The coating thickness and surface roughness showed a tendency to increase with the increasing CA concentration in the electrolyte. It was observed that the vicinity of plasma channels were Zr-rich, while their surroundings were rich in Si and Ca elements. The outer region of the coating was denser compared to inner region consisting of Zr-rich porous structure.