模拟高放废物地质处置环境下重碳酸盐浓度对低碳钢活化/钝化腐蚀倾向的影响  

ACTIVE/PASSIVE BEHAVIOR OF LOW CARBON STEEL IN DEAERATED BICARBONATE SOLUTION

作　　者：文怀梁 董俊华[2] 柯伟[2] 陈文娟[2] 阳靖峰[2] 陈楠[2] 

机构地区：[1]中国科学技术大学化学与材料科学学院,合肥230026 [2]中国科学院金属研究所金属腐蚀与防护国家重点实验室,沈阳110016

出　　处：《金属学报》2014年第3期275-284,共10页Acta Metallurgica Sinica

基　　金：国家自然科学基金资助项目51071160~~

摘　　要：在除氧的HCO-3溶液中,采用原位测量开路电位方法研究了HCO-3浓度对低碳钢腐蚀活化/钝化状态的影响,用SEM观察了低碳钢电极在除氧的HCO-3溶液中长期腐蚀后的表面形貌,用电化学阻抗谱(EIS)方法研究了电极的腐蚀演化特征及规律,用XRD方法检测了腐蚀产物的相组成.结果表明,低碳钢的开路电位随浸泡时间的延长以及HCO-3浓度的升高而升高;长期浸泡后,在0.01 mol/L HCO-3溶液中低碳钢的阳极溶解处于极限扩散状态,而在高于0.02 mol/L HCO-3溶液中处于钝化状态;锈层的主要腐蚀产物为a-FOOH和Fe3O4.As a kind of clean, efficient and relatively safe energy, nuclear energy has been widely used around the world. The high-level radioactive waste （HLRW） generated in the nuclear has also become a major risk, so the disposal safety of HLRW will be especially important. The planned concept of China＇s HLRW disposal program is a shaft-tunnel model located in saturated zones in granite. The metal container for sealing the HLRW is the key because its interaction with the ground water will lead to the leak of the HLRW during the long repository time. Beishan is a selected repository area and the ground water contains a bicarbonate （HCO3-） buffer solution. Therefore, as a candidate material of the container, the active/passive state of low carbon steel in the ground water with HCO3 - is of significance, which determines the container＇s service life. The active state will ensure that the container achieves the designed life under general corrosion, and moreover the passive state will degrade the container＇s life under stress corrosion cracking （SCC） caused by pitting corrosion. In this work, the effect of HCO3- on the corrosion behavior of low carbon steel was examined in deaerated bicarbonate solutions （pH 8.3） over 50 d. The presence of HCO; enhanced both the anodic Fe dissolution and cathodic hydrogen evolution reaction. The situmeasurement of corrosion potential revealed that the increased concentration of HCO3 - led to the high corrosion potential. When the concentration of HCO3- was 0.01 mol/L, the corrosion potential was in the active region. When the concentration of HCO3- was higher than 0.02 mol/L, the corrosion potential was in the passive region. EIS results showed that the charge transfer resistance, film resistance and the diffusion impedance increased with the increasing HCO; concentration. Results of XRD analysis illustrated that the key corrosion products were mainly composed of Fe3O4 and a-FeOOH.

关 键 词：低碳钢 活化 钝化 高放废物处置 HCO3- 无氧腐蚀 

分 类 号：TF777.1[冶金工程—钢铁冶金]