Optimizing Electrophoretic Deposition Parameters and Corrosion Resistance of Nano-Hydroxyapatite/Chitosan Coatings on Ti-6Al-7Nb Alloy Under Various Current Types.

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Document Type : Original Article

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Department of metallurgy -university of technology-Baghdad- iraq

Abstract

Electrophoretic deposition (EPD) is a highly effective technique for modifying biomaterial surfaces, particularly in biomedical applications. This study investigates the influence of current types—direct current (DC), pulsed direct current (PDC), and alternating current (AC)—on EPD parameters, specifically applied voltage and deposition time, for nano-hydroxyapatite/chitosan (HA/CS) coatings on Ti-6Al-7Nb biomedical substrates. Surface morphology and cross-sectional thickness were characterized using optical and scanning electron microscopy, while adhesion tests assessed the bonding strength between the coating and substrate. Electrochemical polarization tests in simulated body fluid (SBF) were performed to evaluate corrosion resistance. For optimization, Taguchi’s statistical design of experiments was applied to identify the most significant factors and determine optimal deposition conditions. Results showed that a 16.5 µm-thick HA/CS coating was obtained using PDC at 70 V for 6 minutes with an 800-grit finish. Under these conditions, enhanced adhesion and uniform coating distribution were achieved. Analysis of variance (ANOVA) indicated that applied voltage (70.30%) and deposition time (80.10%) were the dominant factors influencing coating thickness and adhesion. Electrochemical evaluation confirmed improved corrosion resistance, with the corrosion rate reduced from 9.662×10⁻³ mm/year for the uncoated alloy to 2.23×10⁻³ mm/year for the coated alloy. Overall, PDC at optimized conditions produced a well-adhered, uniformly distributed HA/CS coating with superior corrosion protection, highlighting the potential of EPD for biomedical implant surface modification.

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Progress in Color, Colorants and Coatings

Articles in Press, Accepted Manuscript
Available Online from 01 November 2025

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