Effect of Coating Time of Electrophoretic Deposition of Hydroxyapatite-Chitosan-Magnesium Oxide Coatings on Ti-6Al-4V Alloys

This research aims to evaluate various coatings on titanium alloy substrates to increase corrosion resistance and surface quality. This involves coating the substrates with layers of Hydroxyapatite (HAP), Chitosan (CS), and Magnesium oxide (MgO) using the EPD technique. The cell voltage value was set to 5 V, while the coating time was set to 5, 10, and 15 min. SEM was used to measure the thickness of the cross-sectional coating layers, and it was also used to show the morphology of the composite coating. From the results 10-minute deposition time has been established as the most optimal to produce an even, thick, uniform, and dense coating with good mechanical properties. The thickness more than doubles with increases in time with the coat almost tripling at 15 minutes and 5 minutes respectively. EDX analysis showed that the elemental compositions of calcium, oxygen, and phosphorus increased after 15 minutes, indicating a dense coating. The research findings indicate that the adhesion force transitions to a marginally positive value of 0.05 nN, suggesting a weak attachment rather than a robust bond. Additionally, Young's modulus shows a significant decline to 3.93 MPa, which signifies a reduction in the stiffness of the material. The surface stiffness decreases to 0.19 nN/nm between 10 and 15 minutes, indicating a loss of rigidity. Although longer coating times may increase thickness, they can also reduce functionality and raise defect risks. This reinforces that electrophoretic deposition (EPD) effectively improves the alloy's surface quality for biomedical applications.