Functional Elements Coatings on the Plasma Electrolytic Oxidation-Treated Ti–6Al–4V Alloy by Electrochemical Precipitation Method

In this study, functional elements coatings on the plasma electrolytic oxidation (PEO)-treated Ti–6Al–4V alloy by electrochemical precipitation method were investigated. Ti–6Al–4V ELI disks were used as specimens for PEO and HA coating. The applied voltage and time were selected to be 280 V and 3 minutes for PEO treatment, respectively. The electrochemical precipitation on the Ti–6Al–4V alloy was carried out using cyclic voltammetry with cycle of 3, 5, 10, and 20 from −1.5 V to 0 V (vs. SCE electrode) in electrolyte containing Ca, P, Mg, Mn, Sr, Zn, and Si ions by cyclic voltammetry after PEO treatment. The morphology changes of the coatings on the PEO treated Ti–6Al–4V alloy surface were observed using FE-SEM and EDS. PEO surface has a uniformly distributed circular shape and a porous surface and the deposition of low cycles in electrolyte containing Mg, Mn, Sr, Zn, and Si-HA coated surfaces show uniform circular and granular structures. The precipitates of Mg, Mn, Sr, Zn, and Si-HA on the PEO treated surface showed a large number of circular particles as the number of deposition cycles increases with a mixture of rod-shaped particles and petal-shaped particles around pores. The precipitate nucleates around the pore and grows rapidly as the cycles increase.