Activation energy of UO2 and UO2+x sintering

Two methods were used to determine, in non-isothermal conditions, the sintering activation energy of UO2 and UO2+x oxides, namely the temperature increment method and the constant heating rate method. The second method is easily applied to determine activation energy with a very small standard deviation, and to check that a single process is involved during densification. This study confirmed that activation energy is significantly reduced for O/U ratios between 2.01 and 2.17 in comparison with O/U=2.00. In contrast, it is high when there is a high proportion of U4O9 during sintering. Special attention is being paid to the influence of oxygen concentration preparation method on sintering activation energy kinetics.