Graphene nanoplatelets-reinforced magnesium metal matrix nanocomposites with superior mechanical and corrosion performance for biomedical applications

Abstract

Magnesium (Mg) metal matrix composites (MMCs) reinforced with graphene nanoplatelets (GNPs) have been developed by powder metallurgy (PM). GNPs with different concentrations (0.1, 0.2, and 0.3 wt.%), layer thicknesses (5 nm and 9 nm), and particle sizes (15 µm and 5 µm) were dispersed into Mg powder by high-energy ball-milling processes. The microstructure and mechanical properties of the fabricated composites were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), Raman spectroscopy (RS), and compression tests. The corrosion resistance was evaluated by electrochemical tests and hydrogen evolution measurements. The cytotoxicity of Mg-GNPs composites was assessed using osteoblast-like SaOS2 cells. The results indicate that GNPs are excellent candidates as reinforcements in Mg matrices for the manufacture of biodegradable Mg-based composite implants. GNP addition improved the mechanical properties of Mg via synergetic strengthening modes. Moreover, retaining the structural integrity of GNPs during processing improved the ductility, compressive strength, and corrosion resistance of the Mg-GNP composites. Cytotoxicity assessments did not reveal any significant toxicity with the addition of GNPs to Mg matrices. This study demonstrates that Mg-xGNPs with x < 0.3 wt.%, may constitute novel biodegradable implant materials for load-bearing applications. Keywords: In vitro cytotoxicity, Biocorrosion, Magnesium-graphene composite, Mechanical properties, Strengthening mechanisms