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

• Cr3C2 nanopowders have been synthesized by chemical-reduction route in an autoclave.
• This synthesis of Cr3C2 powder through this technique is our first reporting.
• Transformation kinetics for the formation of Cr3C2 has been discussed.
• Chromium carbide is thermally stable even at the elevated temperatures.

Chromium carbide nanopowder (Cr3C2) has been synthesized from chromium oxide (Cr2O3) by chemical-reduction 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 °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 3.5–4 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.

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