Low temperature consolidation of hydroxyapatite-reduced graphene oxide nano-structured powders

In this study, hydroxyapatite-reduced graphene oxide (HA-rGO) powders were first synthesized in situ using a hydrothermal method. These powders were then consolidated using a cold sintering method. The solvent used in this method was water + dimethylformamide + brushite which was added to the powders at different ratios. The sintered samples were then evaluated using X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, high-resolution transmission electron microscopy, and Vickers microindentation. The results of this study showed that the best conditions for the sintering of rGO-HA nanopowders were a temperature of 200 °C, a holding time of >30 min, and a pressure of 500 MPa. The best mechanical properties were achieved when the solvent content was considered to be 20 wt%. Crack deflection and graphene bridging were among the mechanisms that increased the fracture toughness of these nanocomposites. By adding 1.5% rGO, the fracture toughness of this nanocomposite (using the cold sintering method) was approximately equivalent to that of spark plasma sintered HA. In this study, hydroxyapatite-reduced graphene oxide (HA-rGO) powders were first synthesized in situ using a hydrothermal method.