Hydroxyapatite coatings on Mg-Ca alloy prepared by Pulsed Laser Deposition: Properties and corrosion resistance in Simulated Body Fluid

Magnesium (Mg) alloys are very promising biocompatible materials for biodegradable biomedical implants, however, the main problem in using them is their fast degradation in the conditions of human body. In this work, we coated Mg-Ca (calcium) alloy substrate with hydroxyapatite (HA) to improve its resistance to corrosion and to control the in vitro degradation. Pulsed Laser Deposition technique was applied to deposit HA coatings. Their properties were investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy, high resolution transmission electron microscopy, Vickers microhardness, and Tafel plot electrochemical technique. The substrate temperature was ranged in the interval from room up to 400 °C. According to the obtained results, the recommended substrate temperatures are 200-300 °C, since higher ones lead to the HA decomposition. Furthermore, the HA films deposited at 200 and 300 °C show good corrosion resistance in Simulated Body Fluid. The obtained coatings are promising for a perspective use in biomedical implant applications.