Adhesion Strength of Hydroxyapatite Coating on Titanium Alloy (Ti-6Al-4V ELI) for Biomedical Application

Abstract

Implantation using titanium Ti-6Al-4V ELI still has disadvantages, in particular, low osseointegration cause of less bioactive of the material. Hydroxyapatite was then applied as a coating material to increase the bioactivity and the osseonintegration as well. The Ti-6AL-4V ELI samples were coated with the hydroxyapatite using the electrophoretic deposition (EPD) method, with voltage variations of 5, 8 and 11 volts for 5 minutes and variations in deposition time for 5,8 and 11 minutes with voltage of 8 volt. Surface properties (coarseness, coating mass, thickness, and surface coverage) were then determined by using related equipments. Adhesion strength the HA layer was tested a cross-cut test method. The results showed that the EPD could be used properly to coat the Ti-6Al-4V ELI material with hydroxyapatite. Voltage and deposition time influence coating layer properties that is related to adhesion bonding of the layer on the metal surface. Applying the voltage of 8 volt for 5 minutes resulted in optimal surface properties with coating roughness of hydroxyapatite layer (Ra) as much as 0.88. The removed area after the cross-cut tape test is 2.25%, which means adhesion strength between the coating layer and the subtrate is high enough. A relatively high hydroxyapatite mass (0.3 mg), is covering the material surface with a surface coverage of 82.1%, and the average coating thickness is 73.3 μm. Such kind of coating layer characteristics could improve bioactivity, biocompatibility and thus enhancing osseonintegration capacity of prosthetic medical implants.