Figure 1. Scanning electron micrographs of the graphene that solves the problems regarding insufficient exfoliation of the graphite powder and deterioration in the electrical conductivity and thermal conductivity.
The high-resolution scanning electron micrographs are illustrated in Figure 2 for the graphene that solves the problems regarding insufficient exfoliation of the graphite powder and deterioration in the electrical conductivity and thermal conductivity. The raw graphene powder can contain graphene nanoparticles consisting of stacks of graphene sheets having a platelet shape. The graphene particles may have an average thickness of about 6-8 nm and a typical surface area of about 80 to 200 square meters per gram. The graphene particles have an average particle diameter of about 8-20 microns. Graphene nanoplatelets may have naturally occurring functional groups like ethers, carboxyl, or hydroxyls that can react with atmospheric humidity to form acids or other compounds. These functional groups are present on the edges of the particles and their weight fraction varies with particle size. The liquid precursor is a suspension containing graphene solids. The amount and concentration of the graphene raw material liquid precursor can depend on the desired amount, concentration, and use of the resultant product of the process. A smaller distribution of graphene, for example, from about 0.05 percent by weight to about 60 percent by weight relative to the total weight of a liquid dispersion containing the graphene, would more easily disperse at the submicron level in the liquid dispersion, when compared to a greater weight fraction of graphene in the liquid dispersion. Smaller dispersions result in ease of addition of graphene to other desirable emulsions, for example, to enhance the uniform coating matrix for protection attributes graphene can provide to the coating. A non-limiting example of the silica that can be used is fumed silica. Silica fume is an ultrafine powder collected as a by-product of the silicon and ferrosilicon alloy production. It may consist of amorphous spherical particles with an average particle diameter of about 80-280 nm, for example, about 200 nm, without the branching of the pyrogenic product. The concentration of silica, for example, fumed silica, can be in the range of about 0.08 percent by weight to 28 percent by weight in the liquid precursor or any subrange thereof, for example, about 0.2-20 percent by weight, about 3-6 percent by weight, or about 4-6 percent by weight. A concentration of fumed silica in the range of about 0.2-20 percent by weight can modify nonpolar solvents to have a viscosity of higher than 80 Sabol seconds, for example, to form ringing gels.