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

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 into 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 diffraction 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 gas-solid mathematical formulations, the rate controlling step in the reduction process was determined and proved to be the interfacial chemical reaction at the initial stages, while at the final stages, a combined mechanism of solid-state diffusion and interfacial chemical reaction was the rate controlling step.