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 degrees 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 (Delta d/d(002) similar to 0.002) regions of coherent scattering with interlayer spacing d(002) 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. (C) 1998 Elsevier Science Ltd. All rights reserved. References: 18
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