In situ reduction of graphene oxide nanoplatelet during spark plasma sintering of a silica matrix composite

Well dispersed silica-graphene nanoplatelet (GNP) and silica-graphene oxide nanoplatelet (GONP) composites were fabricated by optimising their processing conditions. Different processing methods, including colloidal and powder processing, were investigated using different solvents. High temperature and inert environment during SPS resulted in the reduction of the GONP during sintering. The in situ reduction of GONP in the SPS was investigated for various sintering times and temperatures, and characterised using Raman spectroscopy and XRD analysis. The composite sintered at 1200 °C, 50 MPa pressure and 15 min dwell time confirmed the recovery of the crystalline graphitic phase of GNP after reduction without crystallising the silica matrix. GONP was found to inhibit the crystallisation of the silica matrix at higher sintering times and temperatures possibly due to increased viscosity and reduced mobility of the silica particles bound to GNP.