Corrosion resistance of uranium specimens treated by
supercritical carbon dioxide (SCCO-2) was investigated in the atmosphere
of 70% relative humidity at 60 ℃. The surface structure and chemical composition of uranium being treated was studied using auger electron spectrum (AES) and x-ray diffraction (XRD) method. Results showed that the corrosion of
specimens treated by SCCO-2 of 10 MPa and 60 ℃ for 3 hours or 4.5 hours were both slower than the specimens without treatment. The pressure influence experiments revealed that the SCCO-2 of 10 MPa had a better effect than the SCCO-2 of 8 MPa or 15 MPa in improving the corrosion resistance of uranium at the same pressure (10 MPa) and the same time (3 hours). As to the temperature, the experimental results indicated that 60 ℃ was better than 50 ℃ at the pressure of 10 MPa for 3 hours. Among all experiments, the best corrosion-resistance was obtained under 10 MPa SCCO-2, 60 ℃ for 3 hours and an additional 2 MPa CO-2 dipping for 108 hours. AES results showed that O and C had been introduced to the surface layer. XRD indicated the major reaction product of uranium and SCCO-2 was UO-2. The mechanism of corrosion resistance improvement was proposed too.