Improved strength, toughness and in vitro bioperformance of graphene nanosheets on plasma sprayed hydroxyapatite coatings

Abstract Graphene nanosheet (GNS) reinforced HA coating on Ti6Al4V substrate, fabricated using plasma spray, was developed for biomedical applications. Microstructural observation corroborated that the adding GNSs homogeneously distributed in the GNS/HA coating with typical lamellar structure featured by GNSs acting as binder between the discrete HA splats. Meanwhile, GNSs were observed to get in direct contact with HA matrix and form a clean GNS-HA interface without interfacial product. Results of various indentation tests showed simultaneous improvement in both indentation yield strength (~379 MPa) and fracture toughness (0.78 ± 0.17 MPam1/2), mainly attributing to synergetic toughening and strengthening mechanisms associated with the adding GNSs such as load transfer, GNS pull-out, inter-layer sliding of a GNS, crack branching, GNS bridging and crack deflection. In addition, the GNS/HA coating exhibited improved biocompatible with MG-63 cell in terms of its attachment, adhesion strength, proliferation and differentiation. Hence, the GNS/HA composite coating with improved strength, toughness and enhanced biocompatibility makes it a promising candidate for bone regeneration and implantation.