EFFECT OF REDOX REACTION ON THE SINTERING BEHAVIOR OF CERIUM OXIDE

Hydrothermally synthesized nano-size CeO2 powders, chemically precipit ated CeO2 powders and commercial micron-size CeO2 powders were investi gated by DTA/TGA and TEM. The sintering behavior of these powders was studied by continuous monitoring of the shrinkage kinetics. The micros tructural features of the sintered specimens were observed by SEM. The sinterability of the CeO2 powder compact increased with decrease in p article size. During the high temperature sintering process a redox re action occurred, i.e. CeO2 was reduced to Ce2O3, and oxygen gas was re leased. The redox reaction influenced the sintering behavior of CeO2, resulting in a decrease in density and microcracking for the hydrother mally synthesized nano-size CeO2 powder compacts, and sagged points in the sintering curves for the chemically precipitated and commercial m icron-size CeO2 powder compacts. It was found that the redox reaction of ceria produced additional pores during the sintering process and th us a much higher temperature was needed to achieve a high density. (C) 1997 Acta Metallurgica Inc.