In-situ synthesis of chromium carbide (Cr3C2) nanopowders by chemical-reduction route

Chromium carbide nanopowder (Cr3C2) has been synthesized from chromium oxide (Cr2O3) by chemicalreduction route under autogenic pressure of hydrogen and CO gases at 87 MPa. The reduction of Cr2O3 to Cr3C2 has taken place at a relatively low temperature (700 degrees C) in the presence of Mg in an autoclave. The increased pressure of hydrogen and CO gases facilitates the reduction and carburization simultaneously which helps in reducing the reaction temperature. The nanopowder shows faceted morphology as observed in TEM. High resolution transmission electron micrographs reveal that the size of Cr3C2 powders varies in the range of 30-40 nm and is coated by 12-13 layers of carbon with average thickness of 35-4 nm. Thermal stability of the as-obtained product was investigated by TGA/DTA analysis. Based on the experimental results, possible reaction mechanism for the transformation and formation of nanopowder is discussed in the light of the obtained structure. (C) 2014 Elsevier Ltd. All rights reserved.