Effect of nano-HA content on the mechanical properties, degradation and biocompatible behavior of Mg-Zn/HA composite prepared by spark plasma sintering

Highlights: • The high density and completely solid solution Mg-5.5Zn/HA composite was successfully fabricated by Spark plasma sintering (SPS). -- Abstract: Recently, Mg-Zn alloy had been investigated as biodegradable material for fabricating orthopedic implants. In this paper, nano-hydroxyapatite (nano-HA) [Ca₁₀(PO₄)₆(OH)₂] was uniformly distributed on the surface of magnesium particles by ball milling process, and then the composite of Mg-5.5Zn/HA was successfully fabricated by spark plasma sintering (SPS). Effect of the nano-HA content on the compressive strength and the bioactivity in vitro (corrosion behavior, cytotoxicity) of the composite was analyzed. Results indicated that with the increasing of the nano-HA content (from 0 to 10 wt%), the compressive yield strength is improved remarkably. Comparing with Mg-5.5Zn alloy, of the nano-HA (10 wt%) can improve the compressive yield strength by 43% and bending strength by 14%. Furthermore, the in-vitro immersion tests revealed the positive and negative effects of nano-HA content on the corrosion behavior of Mg-5.5Zn/HA composite. The nano-HA can improve the degradation resistance of the Mg-5.5Zn matrix. Addition of 10 wt% HA can decrease the corrosion rate by 49%. Furthermore, the composite exhibits acceptable cytotoxicity to L-929 cells, and impressive potential to be used as an orthopedic implant material.