金属铀环境腐蚀的表面状态研究

Surface States of Metal Uranium With Atmospheric Corrosion

采用显微激光拉曼和傅立叶变换红外光谱技术,结合扫描开尔文力显微镜,在线研究了金属铀在大气环境中、一定温度范围内样品表面腐蚀的微区形貌和反应产物的变化情况。结果表明,金属铀在室温时表面微区形貌呈球形凸凹粒状不均匀分布,且在颗粒边缘和凹坑处表面电位较高,易发生点蚀。在大气环境条件下会吸附空气中的O2、H2O和CO2反应生成UO2、铀酰化物和碳酸盐等,不同温度加热,铀表面首先出现活性腐蚀亮斑,并逐渐积累长大,其主要氧化产物UO2在260℃以上开始转化为U3O8。

Variations of microscopic morphology and oxidation products of metal uranium were in-situ investigated from room temperature to 400℃ in air with micro laser Raman spectroscopy（LRS）, Fourier transform infrared（FT-IR） spectroscopy, and scanning Kelvin probe force microscopy（SKPFM）, respectively. The results show that the surface microscopic morphology of uranium show pockety global knaggy in room temperature. The surface potential of uranium is higher around the granules and in the hollows, and dot corrosion takes place more easily on the surface of uranium. Furthermore, the surface of uranium can adsorb and subsequently react with oxygen, water and carbon dioxide in air, forming uranium dioxide, uranyl compounds, carbonate, etc.. Heated up under different temperature, some active corroded light spots appear on the surface of uranium at the beginning of heating, and they get together and grow up gradually. The major corrosion product is uranium dioxide （UO2） that begins to change into triuranium octoxide （U308） above approximate 260℃.