Compressibility of Pyrolytic Graphite

Abstract

The compressibility of pyrolytic graphite has been dynamically measured at pressures up to 0.5 megabar by utilizing explosive‐generated shock waves. Shock and free‐surface velocities normal and parallel to the original plane of graphite deposition were measured optically. The Rankine—Hugoniot shock‐wave equations were used to determine the compression points corresponding to the measured velocities. The measurements failed to distinguish statistically between the two major crystal directions in regard to dynamic compressibility characteristics. The measured pressure—volume data for pyrolytic graphite and the results of Alder and Christian on natural graphite differ significantly at pressures above 100 kilobars. Within the range of the present experiments no transition of pyrolytic graphite to diamond was found.