Intercalation of Large Flake Graphite with Fuming Nitric Acid

In this work, the possibilities of introducing nitric acid molecules with a solution concentration of 75–98% into graphite matrices in the form of synthetic quasi-monocrystal graphite and natural graphite of four different farcical compositions were determined in order to identify factors of the acid concentration and graphite size on the production process and properties of graphite foil. The actual stage of graphite intercalation in the resulting compound was determined by X-ray diffraction analysis (XRD). The differences in the temporal patterns of the intercalation process for different intercalation stages (from 2 to 5) are demonstrated. The obtained acid solutions were used in the manufacturing of flexible graphite foil from natural graphite of four different particle size distributions. The mass characteristics of the intermediate and final products were determined as the graphite was treated with these solutions. The actual difference in the characteristics of the raw materials and intermediate synthetic products was recorded by measuring the electrical conductivity of the final material, graphite foil. Analysis of the results has shown that a decrease in the acid concentration of a solution leads to an increase in the intercalation stage. Weight gains due to the formation of oxygen-containing groups and the introduction of water and acid were reduced by this effect, whereas the yield of the final product (thermally expanded graphite) increased. Foil made of thermally expanded graphite obtained from intercalated compounds of high stages had greater electrical conductivity. An improvement in the conductive properties of the material implies that there should be fewer defects in its structure.