Dip Coating of Nano Hydroxyapatite on Titanium Alloy with Plasma Assisted γ-Alumina Buffer Layer: A Novel Coating Approach

This paper reported a novel coating approach to deposit a thin, crack free and nano-structured hydroxyapatite (HA) film on Ti6Al4V alloy with Al2O3 buffer layer for biomedical implants. The Al2O3 buffer layer was deposited by plasma spraying while the HA top layer was applied by dip coating technique. The X-ray diffraction (XRD) and Raman reflections of alumina buffer layer showed α- to γ-Al2O3 phase transformation; and the fractographic analysis of the sample revealed the formation of columnar grains in well melted splats. The bonding strength between Al2O3 coating and Ti6Al4V substrate was estimated to be about 40 MPa. The presence of dip coated HA layer was confirmed using XRD, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis. The SEM images exhibited that HA top layer enveloped homogenously the troughs and crests of the underneath rough (Ra = 2.91 μm) Al2O3 surface. It is believed that the novel coating approach adopted might render the implant suitable for rapid cement-less fixation as well as biocompatible for longer periods.