Microwave sintering studies in ZrO₂-CeO₂ system

Abstract

Complete sintering of Zr0₂-Ce0₂ pellets of compositions varying from pure Zr0₂ to pure Ce0₂ has been achieved within 35 min using a cooking microwave oven of 980- W power and operating at 2.45 GHz. Densification of 95 % and above was achieved in most cases. The laboratory temperature phase boundaries have been established, which indicate a slight departure of the compositional limits of phase stability compared to those obtained from conventional sintering. The observations also confirm that the formation of composition-dependent phases is a function of the sintering time. Formation of metastable phase Ce₂Zr₃0₁₀ (ø phase) was not observed. Also, cubic phases were generally oxygen deficient and hence no t' -(Ce,Zr)0₂ resulting from diffusionless C_ss→ T_ss transformation at high ceria compositions was found to form. The Vickers hardness value was maximum for mixed t-(Ce,Zr)0₂ + c-(Ce,Zr)0₂ system and minimum for cubic solid solution. The apparent toughness values was maximum for the t-(Ce,Zr)0₂ phase and the value was minimum for the pure cubic system. Microwave sintering seems to be superior to the conventional sintering process.