摘要
在HCO_3^-和Cl^-浓度不同的溶液中,用循环极化的电化学测试方法和SEM,对Cu的循环极化行为和点蚀表面形貌进行了研究.结果表明,该体系中Cu的腐蚀行为可概括为活性溶解型腐蚀、钝化型腐蚀、活性溶解型点蚀和钝化膜破裂型点蚀等4种类型;在HCO_3^-或Cl^-单独存在环境中,Cu表面不发生点蚀,只有Cl^-和HCO_3^-共同存在且起协同作用时,Cu表面才发生点蚀;活性溶解型点蚀区域中,点蚀敏感性随Cl^-浓度的升高而增大,而随HCO_3^-浓度的升高先增大后减小;钝化膜破裂型点蚀区域中,点蚀敏感性随Cl^-浓度的升高和HCO_3^-浓度的降低而增大.
The strategy for disposal of high-level radioactive waste in china is to enclose the spent nuclear fuel in sealed metal canisters which are embedded in bentonite clay hundreds meters down in the bed-rock. The choice of container material depends largely on the redox conditions and the aqueous environment of the repository. One of the choices for the fabrication of waste canisters is copper, because it is thermodynamically stable under the saline, anoxic conditions over the large majority of the container lifetime. However, in the early aerobic phase of the geological disposal the corrosion of copper could take place, and the corrosion behavior of copper would be influenced by the complex chemical conditions of groundwater markedly. Pitting corrosion of copper often takes place in power plants or air-conditioning condensate water. The corrosion environment usually contains HCOa, SO2- and Cl-. In the early stage of geological disposal, if the aerobic water with HCO3-, SO4 2- and Cl- immersion repository, the pitting corrosion of copper may occur. Some researchers believed that SO4 2-and Cl- would promote the occurrence of pitting corrosion of copper, and HCOa will lead to surface passivation and inhibit pitting. It is considered that in the solution with HCO30 and SO2-, HCOacould firstly promote and then inhibit pitting. However, there is no systematic work about pitting in the solution with HCO3 and Cl-. In this work, the cycle polarization behavior and surface morphology of pitting on copper has been investigated in HCO3and Cl-mixed solution, respectively by electrochemical cyclic polarization test and SEM. The results showed that the circular polarization curves of copper could be divided into four types. The pitting on the surface of copper occurs only in the environment with both Cl-and HCO3. In the area of active dissolve pitting, the pitting susceptibility increased with the increase of concentration of Cl-, while it increased then decreased with the increase of the concentration of HCO3-. In the area of passive film rupture pitting area, pitting susceptibility increased with the increase of concentration of Cl- and with the decrease of the concentration of HCO3-.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第11期1365-1373,共9页
Acta Metallurgica Sinica
基金
国家自然科学基金资助项目51071160~~
