Experimental kinetic study of oxidation of uranium monocarbide powders under controlled oxygen partial pressures below 230 degrees C

C. Berthinier (1) , C. Rado (1) , O. Dugne (1) , M. Cabie , C. Chatillon (2) , R. Boichot (2) , E. Blanquet (2)

1 DTEC - Département de Technologies du Cycle du combustible
2 SIMaP - Science et Ingénierie des Matériaux et Procédés

Uranium monocarbide (UC) powders are known to be easily oxidised by gas mixtures containing oxygen. In this study, the oxidation of UC micron powders was followed by isothermal thermogravimetry at temperatures ranging from 100 degrees C to 230 degrees C in two different gas mixtures: synthetic air and 97%N-2 + 3%O-2. X-ray diffraction tests conducted on powders after their oxidation showed that small crystallites of UO2 oxide are formed. Furthermore, an analysis of mass gain showed that the carbon initially linked with the uranium is not oxidised but retained in oxide layers. Additionally, this kinetic study revealed that the rate-limiting step mechanism governing the oxidation of UC powders is a diffusive process that follows the Arrhenius law regarding temperature. Finally, it was discovered that cracks occur in grains once a given fractional conversion has been reached

Domaines: Matériaux

C. Berthinier, C. Rado, O. Dugne, M. Cabie, C. Chatillon, et al.. Experimental kinetic study of oxidation of uranium monocarbide powders under controlled oxygen partial pressures below 230 degrees C. Journal of Nuclear Materials, 2013, 432 (1-3), pp.505-519. ⟨10.1016/j.jnucmat.2012.08.002⟩. ⟨hal-00850222⟩