Titania/hydroxyapatite bi-layer coating on Ti metal by electrophoretic deposition: Characterization and corrosion studies

Titania hydroxyapatite (HAp) hi-layer coating on Ti metal substrate with improved adhesion strength is fabricated by a simple two step processes: electrodeposition of Ti sol and electrophoretic deposition of HAp powder, followed by heat treatment at 800 degrees C. At optimized process parameters, the bi-layer developed consists of dense, thin and crystalline titania interlayer with porous, thick and crystalline HAp top layer. The heat treatment of bi-layer coating allows elemental intermixing at the interface of TiO2 and HAp, as determined by energy dispersive X-ray spectroscopy (EDX) and Raman spectra analysis. Compared to monolithic HAp coating, the TiO2/HAp bi-layer coating shows significant enhancement in the adhesion strength (48 MPa) as well as corrosion resistance without compromising its biocompatibility. The steep increase in adhesion strength is believed to be due to mechanical interlocking and diffusion bonding at the interface. Presence of dense titania interlayer in the hi-layer coating reduces the corrosion current in Ringer's solution to a negligible value (similar to 100 nA). (C) 2011 Elsevier Ltd and Techna Group S.r.l. All rights reserved.