The effects of sulfur and other impurities on carbon-graphite transitions Original Research Article

The transition to graphite of carbons containing sulfur and the effects of added iron and chromium on this process have been studied using X-ray diffraction analysis and electron microscopy. It was found that after heat treatment in the temperature interval 1300–1600 °C carbons containing at least 1.5 mass% of sulfur, or 0.3 mass% of sulfur and 1.5 mass% of added Cr2O3 become heterogeneous; they consist of an ultradisperse matrix and of large (> 100 nm) and sufficiently perfect (Δdd002~ 0.002) regions of coherent scattering with interlayer spacing d002 that corresponds to the graphite-crystal structure. When disperse iron is added, the amount of the graphite phase in this temperature interval decreases by a factor of 2.