A novel approach to electroconductive ceramics filled by graphene covered nanofibers. (15th January 2016) - Drozdova, M.
Abstract: In this study, a novel approach to processing electrically conductive and comparatively cost-effective ceramics by incorporation of the graphene coated oxide ceramic nanofibers into alumina matrix is presented. The conductive fillers are produced by chemical vapour deposition of a few-layered graphene shells on a dielectric substrate of alumina nanofibers of 7–10 nm in diameter and an exceptional aspect ratio of 10 7 . Our approach allows utilizing the advantages of reinforcement by fibres and high conductivity of graphene through homogeneous dispersion of the fibres within alumina matrix. The composites are densified using spark plasma sintering at 1380 °C with 40 MPa pressure for 10 min. It is shown that addition of 0.3 wt.% of graphene results in increase in electroconductivity of 13 orders of magnitude as compared to the monolithic alumina. Moreover, a low graphene loading does not result in deterioration of hardness of the produced hierarchically structured composites. The strategy proposed in this work can be extended to other insulating materials to produce advanced composites suitable for high-precision electrical discharge machining. Graphical abstract: Highlights: Chemical vapor deposition of a few-layered graphene shells on a dielectric substrate of alumina nanofibers of 7-10 nm in diameter and an exceptional aspect ratio of 10 7 ; Novel type of nanofillers utilizing the advantages of reinforcement by fibres and high conductivity of graphene; Novel approach to processing electrically conductive ceramics by incorporation of the graphene coated oxide ceramic nanofibers into ceramic matrix; Spark plasma sintering of composites of alumina and graphene-covered alumina nanofibers; Producing of highly electroconductive alumina of enhanced indentation fracture toughness and increased hardness.