HRTEM STUDY OF CARBONS PREPARED BY HTT OF UNBURNED CARBON FROM COAL COMBUSTION FLY ASHES

摘要

1. The microstructural changes occurring during the high temperature treatment of a concentrate of unburned carbon from coal combustion fly ashes have been succesfully monitorized by means X-ray diffraction, Raman spectroscopy and HRTEM.2. As shown by the XRD and Raman parameters, carbon materials with significant degree of structural order were prepared from the unburned carbon concentrate at temperatures ＞ 2400 ℃. However, stricto sensu graphite structures were only observed by HRTEM in the material prepared a 2700 ℃.3. The presence of some mineral impurities, specifically iron and silicon, in the unburned carbon concentrate seems to be responsible for the high degree of structural order of the material prepared. Different mineral crystallized phases such as iron, iron/silicon and silicon/carbon were identified in the materials prepared by coupling HRTEM with EDS.