Combustion synthesis and mechanochemical synthesis of chromium carbide (Cr3C2)

In this investigation, combustion synthesis and the mechanochemical synthesis of chromium carbide (Cr3C2) were studied using chromium oxide, aluminium and carbon powders. XRD technique was used to characterize the product. Without any mechanical activation, ignition of the raw mixture only resulted in aluminothermic reduction of chromites. When the raw powders were mechanically activated for 2 hours, combustion reactions were completed and Cr3C2 was produced. Results of the mechanochemical process indicated that the aluminothermic reduction of chromites proceed with time and is almost completed after 5 hours. Further milling results in dissolution of carbon in chromium and after 7 hours of milling, distinguished peaks for Cr3C2 appeared in XRD results. No peaks for alumina, a by product of the process, were observed in the XRD pattern which means this phase is amorphous. This was confirmed by annealing of the sample at 1100?C for 1 hr which resulted in a sharp peak for alumina in addition to chromium carbide.