Effects of Dispersant on Microstructure and Properties of GPLs/Al2O3 Composite Ceramics via Microwave Sintering

Three dispersants cetyl trimethyl ammonium bromide (CTMAB), N-N dimethyl formamide (DMF) and N-methyl pyrrolidone (NMP) were added to disperse graphene (GPLs) and a type of graphene/alumina composite ceramics was fabricated by microwave sintering. The GPLs dispersion was characterized by Zeta potential, XRD and SEM. The experimental results show that anionic dispersant NMP has the best dispersion effect with no impurities when pH value is 5. Using dispersant NMP, 0.4vol.%GPLs/Al2O3 composites with high dispersion obtains a relative density of 98.76% at 1500°C for 30 min by microwave sintering. The microhardness, fracture toughness and flexural strength of this composites are 19.58GPa, 6.19MPa·m1/2 and 365.10MPa, respectively. Its fracture toughness respectively increases by 47% and 15% than that of composites using dispersants DMF and CTMAB.