Effect of oxygen-to-metal ratio on densification behavior in the sintering process of PuO2 pellets



The effect of oxygen-to-metal (O/M) ratio on the sintering behavior of plutonium oxide pellets was evaluated from shrinkage measurements in isochronal heating from 973 K to 1923 K and isothermal heating at 1573 K and 1923 K. Air and Ar/H2 gas for which its Pmath image/Pmath image ratio was controlled using added moisture (H2/H2O) were used as measurement atmospheres. During isochronal heating, shrinkage began at lower temperature with increasing Pmath image/Pmath image ratio in the Ar/H2 gas atmosphere. On the other hand, shrinkage began at the lowest temperature, 1100K, in the air atmosphere and sintering in air was dominated by two mechanisms. During isothermal heating, the sintering mechanism was evaluated from the shrinkage ratio. In each atmosphere, sintering was dominated by a slow sintering mechanism. Grain growth did not progress in air and it depended on Pmath image/Pmath image ratio in the Ar/H2 gas atmosphere with added moisture. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)