Corrosion behaviour of sintered Mg-2wt%Zn alloy in different biomolecule-rich physiological environments

Abstract

The role of magnesium in the fracture fixation devices fascinates researchers due to its bioabsorbable nature. However, due to a higher degradation rate in a physiological environment, its clinical usage is limited. To investigate the role of Zinc in Mg, specifically its corrosive behaviour in different physiological environments. Mg-2wt%Zn specimens were fabricated through a conventional powder metallurgy route, and the metallurgical aspect was examined by microstructure and XRD analyses. To evaluate the strength of the developed specimen, a microhardness analysis was performed. To investigate its bioabsorbable nature under different physiological environments, the specimens were subjected to electrochemical corrosion analysis in PBS, FBS + PBS, media and collagen. The collagen was synthesised from the tendons of lab-grown rat tails. The results were compared with sintered pure-Mg specimens. The addition of Zinc improved the specimen's strength by forming a secondary phase. It significantly improved corrosion resistance and reduced the hydrogen evolution. The interaction between the protein and the surface resulted in the formation of a protective layer, which reduced the corrosion rate. The addition of Zinc increased the specimen's strength by around 25% through the formation of a secondary phase. Due to the interaction between the protein and the surface, a protective layer formed, reducing the corrosion rate. Further, the addition of Zinc reduced the corrosion rate to 76% and the hydrogen evaluation to 70% in the FBS + PBS environment. The lowest corrosion rate was observed in the collagen environment of around 0.147 mm/year for pure Mg and 0.097 mm/year for Mg-2Zn.