Preparation of HA-Coated Mg-4.0Zn-1.0Ca-0.6Zr(wt%) Alloy and its Biodegradation Behaviors

Abstract

Magnesium and magnesium alloys, as biomaterials, possess many properties that are superior to those of other metals. However, magnesium and magnesium alloys have strong chemical activity and porous and brittle surface oxide film, as degradable implantation materials, their degradation rates are too fast. Hydroxyapatite (HA) has good biocompatibility and biological activity and has become one of the replacement materials of biomedical stiff hemopoietic tissue, but the application of HA biomaterial is hindered because HA is brittle and has low strength. Integrating good mechanical properties of metallic materials with excellent biological performance of HA, the composite obtained by coating HA to the surface of metallic matrix is ideal rehabilitation material of bone tissue. In the present study, a new Mg-4.0Zn-1.0Ca-0.6Zr (wt%) was designed according to the requirements of biocompatibility. The microstructures and the mechanical properties of the new alloy were investigated by experiment. The excellent mechanical properties fully meet the service requirements of human bone tissue for mechanical property. Flat and dense hydroxyapatite coating was prepared on the surface of magnesium alloy matrix by preceding alkali heat treatment, electrodeposition and post alkali heat treatment. The Structure and constituent of HA coating and the biodegradation behavior of HA-coated Mg-4.0Zn-1.0Ca-0.6Zr (wt%) alloy were evaluated. Resuls showed that the degradation rate of HA-coated Mg-4.0Zn-1.0Ca-0.6Zr (wt%) alloy in SBF biomimetic solution decreased obviously and tended to be stable after 10 days. As degradable implantation materials, HA-coated Mg-4.0Zn-1.0Ca-0.6Zr (wt%) alloy fully meets the service requirements of human bone tissue.