Influence of thermal treatment on structure and properties of RF-Magnetron calcium phosphate coatings deposited on Mg-based alloy

Mg-based alloys became a material of interest for biomedical applications. The major difficulty in the Mg-based alloy application is its rapid corrosion rate. Various coating methods are used to form a barrier layer onto Mg-based materials. In this work, a thin film of calcium phosphate was deposited on an Mg–0.8 at % Ca alloy using RF magnetron sputtering. As-deposited coatings were in an X-ray amorphous state. Post-deposition heat treatment resulted in the coating crystallization, exhibiting the pure HA phase. Heat-treatment at 450°C for 3 hours did not significantly change the coating integrity and adhesion strength to the Mg–0.8 at % Ca substrate. The Ca/P ratio, however, was changed from 1.85 for as-deposited to 2.00 for heat-treated samples. Both coating and substrate material after heat treatment exhibit preferential crystallographic growth in (002) direction with Tc(002) = 2.86 and 5.79, correspondingly.