Electrophoretic Deposition of Chitosan/Hydroxyapatite/Zirconia Nanocomposite Coatings on Ti–6Al–4V Alloy: Corrosion Behavior and Biological Performance

A nanobiocomposite coating composed of chitosan (CS), hydroxyapatite (HA), and zirconia (ZA) was developed to improve the corrosion resistance and biocompatibility of Ti–6Al–4V alloy. HA and ZA nanoparticles were synthesized via wet chemical precipitation and deposited on Ti–6Al–4V along with CS using electrophoretic deposition. The phase composition and microstructure of the nanoparticles and coatings were characterized by X‐ray diffraction and scanning electron microscopy. Coating thickness, surface roughness, and adhesion strength were measured, yielding an average thickness of 200 µm, Ra of 3.3 µm, and adhesion of 2.1 MPa, respectively. Electrochemical performance was assessed in simulated body fluid via open‐circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy. Corrosion resistance followed the order CS/HA/ZA > CS/HA > bare Ti–6Al–4V. Titanium ion release after 60 days of immersion was reduced from 57.0 ppb (bare alloy) to 22.9 ppb (CS/HA) and 14.9 ppb (CS/HA/ZA). In vitro cytotoxicity evaluated by MTT assay indicated enhanced biocompatibility of CS/HA/ZA coatings. These results demonstrate that incorporation of ZA into CS/HA coatings significantly improves both the electrochemical and biological performance of Ti–6Al–4V alloys, highlighting the potential of CS/HA/ZA nanobiocomposite coatings for biomedical applications.