The effect of rare earth catalyst on carburizing kinetics in a sealed quench furnace with endothermic atmosphere

We study the effect of a rare earth (RE) catalyst on the kinetics of gas ca rburizing of 08F and 8620 steels. Carburizing was conducted in a sealed-que nch furnace employing an endothermic atmosphere with and without RE additio n at 900 degreesC for different times. These experimental results show that compared with conventional gas carburizing the incorporation of RE leads t o an obvious increase in layer depth and carbon (C) concentration profile u nder the same carburizing condition. Cerium (Ce) existing in the carburizin g atmosphere and diffusing into the surface layer does not change the kinet ics law of carburized layer growth. In addition, the calculated results sho w that the reaction constant and the diffusion coefficient of carbon betwee n the gas-solid interface can also be increased during RE carburizing. (C) 2001 Elsevier Science B.V. All rights reserved.