Powder Metallurgical Synthesis of Biodegradable Mg-Hydroxyapatite Composites for Biomedical Applications

Abstract

Biodegradable Mg alloys are a new class of temporary implant materials for musculo-skeletal surgery. Recent studies show that Mg-based alloys can be biocompatible and there is a high demand to design Mg alloys with adjustable corrosion rates and suitable mechanical properties. An approach to solving this challenge might be the use of Mg metal matrix composites (Mg-MMC). In this study, a Mg-MMC composed of ZK60 was investigated as the base material and hydroxyapatite (HA) particles were added for tailoring its properties. The composite was produced by high-energy ball milling followed by hot extrusion. This processing route was chosen, as HA in contact with molten Mg releases a toxic gas (phosphine – PH3). The HA particles were homogeneously distributed in the ZK60 matrix after ball milling and the composite was consolidated by hot extrusion. This work presents the influence of different amounts of HA on corrosion behavior and mechanical properties of the composite. Corrosion properties were evaluated by immersion and electrochemical measurements in physiological media at 37 °C. A slight improvement in the corrosion resistance was observed for Mg-MMC due to the presence of more stable corrosion products. Compression tests were used to measure the mechanical properties. Under compression, samples showed a slight increase in the compressive yield strength with the addition of HA, while the ultimate strength did not change significantly.