The Effect of Sintering Temperature on Bilayers Hydroxyapatite Coating of Titanium (Ti-6Al-4V) ELI by Electrophoretic Deposition for Improving Osseointegration

Abstract

Bilayers hydroxyapatite (HA) coating using electrophoretic deposition (EPD) method has been applied into a biocompatible metal, Ti-6Al-4V ELI, in order to improve bioactivity of the alloy and then to accelerate bone remodeling and osseointegration during implantation. Two steps EPD process wasconducted for obtaining based layer consist of HA nanoparticles using voltage 3 volt for 3 minutes. It was then followed by second layer formation consist of HA micro particles using voltage 5 volt for 5 minutes. The coated alloy was then sintered at temperatures of 700°C, 800°C and 900°C for each 10 minutes within vacuum tube furnace at the sintering rate 20°C/s. Surface morphologies were examined using optical microscope and scanning electron microscope (SEM). The result of this study showed that bilayers hydroxyapatite coating onto Ti-6Al-4V surface was produced through EPD with those parameters. Sintering treatment at temperature 800°C gives thin, dense, even and crack-free coatings. The Ti-6Al-4V ELI surface is almost fully covered by bilayers hydroxyapatite (with surface coverage 98.6%) with adequate bonding (without lost weight of coating layers). An improper coating layer is obtained for lower (700°C) and higher (900°C) temperature. The sintered samples at temperature 900°C have micro cracks, void and debonding layers. It is expected such bilayers hydroxyapatite with sintering at 800°C can initiate mineralization and then make a quick osseointegration.