Isothermal reduction kinetics of Fe2O3 mixed with 1-10% Cr2O3 at 1173-1473K

Fired pure and 1-10% Cr2O3-doped Fe2O3 compacts, were isothermally reduced with H-2 at 1 173-1 473 K. Compacts are prepared by mixing chemically pure powders of Fe2O3 and Cr2O3 in the required ratios then pressed at 30 kN int o cylindrical form of compacts before being fired at 1 473 K for 20 hr. The characteristics of the prepared compacts have been studied using X-ray dif fraction analysis technique and reflected light microscope. The isothermal reduction curves obtained showed that Cr2O3 has a significant effect on the rate of reduction of Fe2O3. From the apparent activation energy and the ga s-solid mathematical formulations, the rate controlling step in the reducti on process was determined and proved to be the interfacial chemical reactio n at the initial stages, while at the final stages, a combined mechanism of solid-state diffusion and interfacial chemical reaction was the rate contr olling step.