地质处置后期无氧阶段X65低碳钢腐蚀行为研究

X65低碳钢在模拟地质处置后期50 ℃无氧模拟地下水溶液中的主要腐蚀类型为均匀腐蚀;利用扫描电子显微镜 (SEM)、能量散射谱 (EDS) 和微区X射线衍射仪 (μ-XRD) 表征X65低碳钢腐蚀产物的形貌、元素和物相组成。结果表明,腐蚀产物有针状和颗粒状两种类型,包含Fe和O两种元素,产物物相为Fe₃O₄;使用失重法测得X65低碳钢平均腐蚀速率在360 d内逐渐从4.17 μm/a降低到1.42 μm/a,腐蚀速率随时间的变化规律符合降幂函数关系式V₅₀=1.36t ^-0.56,腐蚀过程受扩散控制。

Corrosion Behaivour of X65 Low Carbon Steel During Anaerobic Period of High Level Nuclear Waste Disposal

The corrosion type of X65 low carbon steel in an artificial 50 ℃ anaerobic groundwater, which aims to simulate the environment for the later stage of geological disposal of nuclear waste, was studied. It follows that the X65 steel suffered mainly from general corrosion in the simulated groundwater. The morphologies, compositions, and phases of the corrosion product scale formed on the carbon steel surface were examined by using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray micro diffraction (μ-XRD). The results indicated that the scale was mainly composed of needle- and particle-oxides, which contain mainly elements of Fe and O, and they are all magnetite. The measured average corrosion rate of the X65 steel decreased gradually from 4.17 μm/a to 1.42 μm/a in 360 d, which can be described as a power function V₅₀=1.36t ^-0.56, indicating that the film growth process was controlled by diffusion.