Characteristics of multi-layer coatings synthesized on Ti6Al4V alloy by micro-arc oxidation in silver nitrate added electrolytes

- Multi-layer HA/TiO2 coatings containing Ag were synthesized by MAO method.
- Silver nitrate addition in the electrolyte induced crystallization of HA layer formed on the TiO2 layer.
- In vitro bioactivity was enhanced via crystallization of HA layer.
- Ag nanoparticles were detected on the HA layer and provided antibacterial activity.

Multi-layer coatings (composed of outer hydroxyapatite and inner titania layers) have been synthesized on Ti6Al4V alloy for biomedical applications by employing micro-arc oxidation at positive and negative voltages of 400 and 80, respectively. Addition of silver nitrate (at concentrations of 0.1 g/L and 0.4 g/L) into the calcium acetate hydrate and disodium hydrogen phosphate anhydrous containing base electrolyte provided an enhancement in bio- and antibacterial activities of the synthesized coating, while imposing precipitation of silver nanoparticles on the hydroxyapatite layer. It is finally concluded that addition of 0.1 g/L AgNO3 into the base electrolyte is promising for MAO process of titanium-based implants, when the structural characteristics and risk of cytotoxicity are of concern for the synthesized multi-layer coatings.