对NiCu低合金钢在模拟深层地下水环境, 即除氧0.1 mol/L NaHCO₃+0.1 mol/L NaCl溶液中, 原位监测其在长时间浸泡条件下的开路电位变化曲线及阻抗谱的演化, 研究电极表面的腐蚀演化规律, 并与相同条件下低碳钢的腐蚀行为进行比较. 结果表明, NiCu低合金钢在本实验溶液中的耐蚀性要显著优于低碳钢, 尤其是其耐局部腐蚀的能力更优. 合金元素Ni富集在内锈层中, 可能以NiFe₂O₄的形式存在, 而合金元素Cu的富集不明显, 可能的存在形式为CuFeO₂.

The corrosion behaviour of low alloy steel containing Ni and Cu was studied because it is a promising candidate canister material for the disposal of high-level radioactive waste (HLW) in China. Due to the intensely radioactive nature of HLW, the waste has to be prevented from reaching the biosphere for many tens of thousands of years. Deep geological disposal is now considered to be the most preferable option for isolating HLW and it relies on series of natural and engineered barriers, e.g. a metallic canister. However, as soon as the waste package is settled, groundwater would seep back slowly through the outer barriers and ultimately arrive at the surface of the canister. Accordingly, there comes the groundwater-induced dissolution of the canister and subsequent transport of radionuclides through the barriers. That is to say, the effectiveness of radionuclide retention and isolation depends mostly and finally on the corrosion resistance of metallic canisters in deep groundwater environments. In this work, the test solution is deaerated 0.1 mol/L NaHCO₃+0.1 mol/L NaCl, simulating the deep groundwater environment. The evolution of corrosion of NiCu low alloy steel in the test solution was investigated by electrochemical measurements. XRD was used to illustrate the composition of formed corrosion products. SEM was used to observe the electrode surface morphology and the cross section of the rust layer. The electrochemical results showed that low alloy steel has a lower corrosion rate and is less prone to localized corrosion than low carbon steel. In order to understand the mechanism of alloying elements, EDS and EPMA were used to analyse the distribution of alloying elements cross-sectional. XPS and E-pH diagram were used to estimate the possible existence form of alloying elements. By means of EDS and EPMA, it was founded that Ni is concentrated in the inner rust layer while the enrichment of Cu is not so obvious. XRD, XPS and E-pH results indicated that Ni and Cu are existed in the form of NiFe₂O₄ and CuFeO₂ respectively.