Oxidation kinetics of nitrided uranium determined by ultraviolet-visible reflectance spectroscopy

The oxidation kinetics of a uranium surface treated by pulsed laser nitriding was studied using reflectance spectroscopy. The growth of the oxide thickness generally followed a parabolic growth model for the nitrided uranium with pure O2, which agreed with the diffusion barrier model. The activation energy was 98 kJ/mol and was obtained by monitoring the oxide growth in the temperature range 400-460 K. As a comparison, the growth of the oxide thickness of untreated uranium was also monitored, which indicated that the nitriding treatment improved the corrosion resistance of uranium. This may be due to the formation of UNO compounds on the surface of nitrided uranium after oxidation, which can resist the diffusion of oxygen ions into the inner layer.