Synthesis and evaluation of magnesium/co-precipitated hydroxyapatite based composite for biomedical application

Owing to its inductive attributes, hydroxyapatite is an ideal reinforcement to tailor the degradation kinetics of magnesium-based temporary orthopedic implants. However, the large difference in the melting temperature of hydroxyapatite and magnesium lead to an insignificant interaction between them during the sintering process, which has been a major limitation in their consolidation. Doping of pure HA with Mg²⁺ and Zn²⁺ ions could be a viable solution by making it coherent with the Mg matrix. Further, such doping also results in a chemistry more similar to the natural apatite in human bone. In this study, Mg²⁺ and Zn²⁺ ions doped hydroxyapatite (CoHA) is synthesized and reinforced to obtain high density in Mg-based composites, fabricated through spark plasma sintering. Composite with 15 wt % CoHA offered ~113% improvement in the ultimate compressive strength. Higher relative density, due to improved consolidation, might be the reason for higher mechanical strength. Hydrogen evolution (up to 64 h) and static immersion studies (up to 28 days) revealed comparatively higher corrosion resistance for 10 wt% CoHA composites. This study gives insight into the potential of fabrication and designing of the M3Z-CoHA composites for temporary orthopedic implants.