Synthesis And Performances Of Graphene And Graphene/Alumina Composites

In2004year the first report for the flee-standing graphene published by Geim, a two-dimensional lattice that thick and closely packed by one atom. It is considered as a promising candidate for various applications and becomes a hot research topic in the field of chemistry, materials science and physics due to its unusual and intriguing mechanical, electric, thermal and optical properties. Moreover, the high-quality sp2carbon lattice, quasi-two-dimensional crystal structure, high mechanical properties and conduting property of graphene provide the basis for the applications in composites. Due to the prior mechanical and other physical properties, graphene can beutilized as the reinforced filler in ceramic-based composites. However, graphene is difficult to produce in large scale and intends to exist in aggregation state. In order to make use of its high tensile strength, Young'S modulus, thermal conductivity, thermo stability and chemical resistance, it is necessary to investigate the morphology and structure deeply.In thispaper, the preparation and dispersion of graphene nanosheets(GNS) were investigated. First, GNS were prepared by the oxidation/exfoliation process of graphite. The morphology and structure of GNS as well as thermal stability property of GNS were studied by SEM, TEM, HRTEM, FT-IR, XKD and TG-DSC. The test results show that single graphene is able to be successfully prepared by reducing graphite oxide and won good electrical conductivity comparable with argent.Moreover, three kinds of surface active agent of cationic CTAB, anionic SDB and nonionic PVP were used to improve dispersion of graghene in aqueous solution. The dispersion of graphene in aqueous solution was studied by absorbancy and zeta potential. The experimental results indicate that graphene particle itself have negative charge.The cationic surfactant(CTAB) was used to improve the dispersion of graphene in aqueous solution but received unfavorable outputs. The anionic surfactant(SDB) can improve the dispersion of graphene in aqueous solution. The nonionic surfactant(PVP) best improve the dispersion of graphene in aqueous solution in three kinds of surfactant. The graphene as the reinforced filler in the ceramic composites was studied. The graphene/ceramic composites were synthesized by two different processes of mixing solid powders and coating in situ to reach the homo-dispersed graphene and alumina ceramics composites with crystalline grains fining. The particles by mixing solid powders process are of coarse size and reunite each other, and the coagulation is evident. The product by coating in situ process is of uniform particle size distribution, regular morphology, and good dispersion.These researches had great academic and practical significances for the broadening of graphene and the promotion of the development of its application in the field of ceramic-based composites.