Effect of Applied Voltage and Coating Time on Nano Hydroxyapatite Coating on Titanium Alloy Ti6Al4V Using Electrophoretic Deposition for Orthopaedic Implant Application

Abstract

Nanoparticles of Hydroxyapatite (HA) were coated onto biocompatible titanium alloy, Ti6Al4V ELI using Electrophoretic Deposition (EPD) in order to improve its bioactivity. Electrophoretic Deposition (EPD) has been selected as the coating method because of the simplicity of the instrument, inexpensive cost, and ability to coat complicated products. This study, therefore, aims to investigate the effect of voltage and coating time of EPD process on increasing of implant mass as a parameter of deposition rate, coating thickness, and surface coverage of the HA on implant screw prototype products. Voltages were controlled in the range of 3, 5, and 7 volt and coating times were in the range of 3, 5, and 7 minutes. Surface morphology was examined using scanning electron microscopy (SEM). Coating thickness was measured by coating thickness gauges. While surface coverage was determined using ImageJ software. Based on the result, applied voltage and coating time affects the mass growth of samples and HA coating thickness in positive correlation. However, on the surface coverage, applied voltage and coating time reach the optimum value at 5 volt and 5 minutes. The best HA coating in which fulfilling the standard for orthopaedic implants was obtained at 5 volts for 5 minutes with mass growth is 0.00107 g, coating thickness are 79.13 µm, and surface coverage is 97.89%. HA coating thickness that produced in this research has fulfilled the desired coating thickness for orthopaedic implant application (50-100µm). SEM micrographs show that nano-HA is coated the alloy surface uniformly at these parameters. It can be concluded that these parameters can be applied to coat titanium Ti6Al4V ELI with HA for improving bioactivity in the orthopaedic application.