STUDIES ON THE KINETICS OF THE CARBOTHERMIC REDUCTION OF CHROMIUM-OXIDE USING THE EVOLVED GAS-ANALYSIS TECHNIQUE

The kinetics of formation of Cr3C2 by the carbothermic reduction of Cr2O3 with graphite was studied in the temperature range 1461-1739 K. The experiments were carried out in a high vacuum chamber with the mechanically mixed reactants in pellet form, compacted at different pressures. The progress of the reaction was followed by monitoring the CO gas evolved by means of a quadrupole mass spectrometer. From the parabolic nature of the rate equation and the dependence of the activation energy of the reaction on the compaction pressure of the pellets, it was concluded that the diffusion of CO gas through the product layer was the rate-controlling step.