Fabrication of Platelet-Like Natural Crystalline Graphite with Nano-Scale Thickness via Layer Distance Expansion

Abstract

Platelet-like natural crystalline graphite with nano-scale thickness was fabricated through low expansion and exfoliation processes. Graphite, as a starting material, had an average particle size of 10 mm. A graphite intercalation compound (GIC) was prepared by mixing sulfuric acid and hydrogen peroxide with the graphite. It was treated at various temperatures and retention times in the furnace to control the expansion ratio, and then ground for size reduction in the attrition mill. The size reduction efficiency increased as the expansion ratio increased to 25 vol%, after which the efficiency decreased again by over 25 vol%. Since the process of size reduction involves repeated exfoliation and expansion of graphite, it revealed a stage-by-stage decrease pattern as the grinding time increased. In this research, the exfoliation rate of platelet-like natural graphite was improved via the low expansion method. Nano-platelet-type graphite with an average particle size of 3 mm was fabricated, but its layer was 20–50 nanometers thick. [doi:10.2320/matertrans.M2009102]