Magnesium (Mg) and its alloys are potential candidates for biomedical applications since they present low density and mechanical properties closer to the bone than other traditional materials as stainless steel or titanium. However, their use is limited in this area due to their high corrosion rate in simulated body fluid and the generation of gaseous hydrogen during their degradation. In this study, hydroxyapatite coatings developed by different ways have been proposed in order to control the degradation rate and to improve the biocompatibility of the AZ31 magnesium alloy. Hydroxyapatite is a biocompatible material found primarily in bones.

The hydroxyapatite coatings have been developed using two different techniques: high velocity oxygen fuel (HVOF) thermal spray and sol-gel process followed by laser treatment. After optimization of process parameters, the coated samples have been microstructurally characterized to evaluate thickness, porosity and other defects and to analyse the coating-substrate adhesion and the possible area affected by the technique used. Furthermore, the crystalline phases present in the coatings have been determined. Then, the degradation rate of the coated samples with time have been tested in Hank’s solution and the corrosion progression through the system has been established. In addition, the coatings developed by both techniques have been compared to select those which present the best performance for the intended application.