Preparation and Characterization of Hydroxyapatite Coating on Ti6Al4V Cylinders by Combination of Alkali-Heat Treatments and Biomimetic Method

Biomimetic method was used to apply hydroxyapatite (HA) coating onto Ti6Al4V cylinders. This process is a physicochemical method in which a substrate is soaked in a solution simulating the physiological conditions, for a period of time enough to form a desirable layer of the calcium phosphate on the substrate. In the present study, specimens were soaked in 5, 10 M solutions of NaOH at temperatures of 60 or 80ºC for 24 and 72 h. Surface of samples were characterized using scanning electron microscopy (SEM) and thin film X-ray diffraction (TF-XRD). The optimum condition was found to be 72 h of soaking in 5 M NaOH at 80ºC. Specimens treated under these optimum conditions were subsequently heat-treated at 500, 600, and 700ºC for 1h in order to consolidate the sodium titanate hydrogel layer. Under the heat treatment condition of 600ºC for 1h and subsequent soaking in simulated body fluid (SBF), apatite formed within 3 days. It was observed that, apatite formation increased significantly, which is an indication of the materials ability for use as a load bearing implant.