We describe three related methods to disperse graphene in solvents with concentrations from 2 to 63 mg/mL. Simply sonicating graphite in N-methyl-2-pyrrolidinone, followed by centrifugation, gives dispersed graphene at concentrations of up to 2 mg/mL. Filtration of a sonicated but uncentrifuged dispersion gives a partially exfoliated powder that can be redispersed at concentrations of up to 20 mg/mL. However, this process can be significantly improved by removing any unexfolaited graphite from the starting dispersion by centrifugation. The centrifuged dispersion can be filtered to give a powder of exfoliated few-layer graphene. This powder can be redispersed at concentrations of at least 63 mg/mL. The dispersed flakes are ~1 μm long and ~3 to 4 layers thick on average. Although some sedimentation occurs, ~26-28 mg/mL of the dispersed graphene appears to be indefinitely stable.

No abstract

No abstract

Graphene has remarkable mechanical properties, which makes it potentially a good reinforcement in ceramic composites. It also has unique electrical and thermal properties, which makes it an attractive filler for producing multifunctional ceramics for a wide range of applications. In the past few years, relatively little attention has been focused on graphene ceramic matrix composites (GCMC) in comparison to polymer composites. This review gives a comprehensive overview on the state of the art of GCMC, including materials synthesis, densification and characterisation. The published literature allows us to define the critical steps for processing GCMC, and identify its influence on the multifunctional and mechanical properties of the composites. Finally, the potential future applications and current research trends in GCMC are presented.