Evaluation of metal ion release and corrosion resistance of ZrO 2 thin coatings on the dental Co–Cr alloys

Abstract

Objectives. The aim of this study was to determine if electrolytic ZrO 2 thin coatings increased the corrosion resistance and decreased the metal ion release of dental cobalt–chromium alloys. Methods. Dental Co–Cr alloys were electrolytically deposited with ZrO 2 ceramic coatings using a 0.0625 M ZrO(NO 3) 2 solution, at various potentials, for 500 s. The electrolytic ZrO 2 gel-coated specimens were annealed at 723 K for 1 h in air. Scanning electron microscopy (SEM) was used to observe the morphology of the ZrO 2 ceramic coatings on Co–Cr alloys. A dynamic polarization test was used to compare the corrosion resistance of the ZrO 2 coated and uncoated Co–Cr alloys in artificial saliva. Metal ion concentrations were determined with graphite furnace atomic absorption spectroscopy (AAS). Results. The SEM micrographs showed that the Co–Cr alloy can be coated with zirconia oxide at −0.7 V more homogeneously and more completely than at −1.5 V. The polarization curves indicated that the ZrO 2 coating on Co–Cr alloys annealed at 723 K for 1 h in air exhibited better corrosion resistance in artificial saliva. The results of the AASs showed that the ZrO 2-coated Co–Cr alloys decreased chromium ion release levels, as compared with the uncoated Co–Cr alloys. The scratch test indicated a good bond strength between the ZrO 2 and Co–Cr alloy. Significance. The electrolytically deposited ZrO 2 coatings on Co–Cr alloys may improve the corrosion resistance and decrease the release of metal ions. It is suggested that the electrolytic ZrO 2 coating method could have a widespread application in dentistry in the future.