Influence of deposition voltage on hydroxyapatite–chitosan coatings on Ti6Al4V

Abstract

This study presents the fabrication and detailed characterization of hydroxyapatite (HA) and chitosan (CS) nanocomposite coatings on sandblasted Ti6Al4V alloy substrates using the electrophoretic deposition (EPD) technique. Titanium alloys are extensively utilized in orthopedic and dental implants Because of their enhanced mechanical performance, as well strong resistance to bio implant corrosion, and excellent compatibility with biological systems. However, their intrinsic bioinert nature often limits biological integration. To address this challenge, HA biochemically similar to the mineral phase of bone was incorporated with CS, a biodegradable and antibacterial biopolymer, to form a hybrid coating aimed at enhancing surface bioactivity. The Ti6Al4V substrates were pre-treated via sandblasting to introduce controlled surface roughness, thereby promoting mechanical interlocking and improving coating adhesion. EPD was conducted using ethanol-based HA/CS suspensions under varied voltages (10, 20, 30, and 40 V), and deposition parameters were optimized to ensure uniform and adherent coatings. The effects of deposition voltage on coating morphology, thickness, porosity, corrosion resistance, and adhesive strength were systematically evaluated. Characterization of the coatings was performed using FESEM, XRD, and Raman spectroscopy to investigate surface topography, phase composition, and structural integrity. Results indicated that higher deposition voltages yielded thicker and more porous coatings, which directly influenced corrosion behaviour and adhesion properties. An optimal voltage range was identified that provided superior coating uniformity, enhanced corrosion resistance, and improved mechanical stability. In conclusion, this work demonstrates that the integration of surface texturing with optimized EPD parameters significantly improves the functional performance of HA/CS coatings on Ti6Al4V alloy.