Effect of thermal treatment on the surface morphology and wettability of hydroxyapatite films deposited by rf magnetron sputtering

The hydroxyapatite (HAP) ceramic, widely used as a biological active coating for the metallic implants in arthroplasty, presents different characteristics depending on the synthesis process. The surface characteristics such as its surface chemistry, surface energy, topography and roughness are important properties to be determined when considering the use of an implant. In the present work, the magnetron sputtering deposition method was used to deposit HAP coatings on Ti6Al4V alloy, in order to investigate the effect of thermal treatment on their surface roughness and wettability. The coatings were investigated for their composition and crystallographic structure by EDX, FT-IR and XRD, as well for their surface morphology by SEM and stylus based surface profilometry. The assessment of the wettability was done by using the sessile drop method, the contact angles for various liquids, the surface free energy and the work of adhesion on water being determined. After annealing the HAP coatings became crystalline, preserved their elemental composition, but exhibited different surface roughness and work of adhesion on water.