Preparation of mesophase-pitch-based graphite foams at atmospheric pressure

Abstract

Mesophase-pitch-based graphite foams have attracted increasing attention because of their broad applications in thermal management, catalysis and so on. However, the common approach of using the high-pressure method for fabricating graphite foams is complex and risky. Herein, this research reports a simple and relatively safe technique for preparation of mesophase-pitch-based graphite foams, which is conducted under atmospheric pressure. Through foaming of mesophase pitch in the presence of epoxy resin at 700°C under atmospheric pressure and graphitization at 3000°C, graphite foam is fabricated. The obtained graphite foam is highly graphitic and has an open pore structure, the interlayer spacing of the (002) plane of which is about 0.3366 nm. Its density is 0.52 g/cm3 with a porosity of 73.5%. The properties of graphite foams can be tailored by modifying pitch particle sizes and foaming temperatures. With an increase in pitch particle size from <25 to 75–150 μm or in foaming temperature from 400 to 850°C, the pore sizes vary from 10–25 to 35–90 μm, and their bulk densities change from 0.50 to 1.11 g/cm3. Also, a foaming mechanism is proposed wherein the residue of epoxy resin can form a framework during heating, in which the pitch softens and decomposes, forming foam. This study suggests a relatively simple and safe method for production of graphite foams from mesophase pitch.