高放废物地质处置环境下处置罐材料的腐蚀行为

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	高放废物地质处置环境下处置罐材料的腐蚀行为
	阳靖峰
学位类型	博士
导师	韩恩厚 ; 董俊华
	2011
学位授予单位	中国科学院金属研究所
学位授予地点	北京
学位专业	腐蚀科学与防护
关键词	高放废物地质处置 Yucca Mountain 北山 C22合金低碳钢 Geological Disposal Of Hlw Yucca Mountain Beishan Alloy C22 Low Carbon Steel
摘要	"本文主要研究了C22合金在模拟美国Yucca Mountain巷道环境中对垢下腐蚀和缝隙腐蚀的耐蚀性，以及模拟北山地区地下水溶液的pH、阴离子对低碳钢活化/钝化腐蚀倾向的影响。在模拟Yucca Mountain巷道环境干湿交替过程中，UZ溶液发生严重酸化，在C22合金表面沉积形成垢层。XRD结果显示垢层的主要成分为Mg2(OH)3Cl。C22合金发生了垢下腐蚀和缝隙腐蚀。当低碳钢处于pH=8的除氧硼酸缓冲溶液中时，低碳钢一直处于活性溶解状态；当低碳钢处于pH值为9或10的除氧硼酸缓冲溶液中时，低碳钢最终处于钝化状态。XRD结果表明，低碳钢在除氧硼酸缓冲溶液中的腐蚀产物由Fe6 (OH)12B4O7和γ-FeOOH组成。在[HCO3-]=0.1 mol/L的除氧重碳酸盐缓冲溶液中，低碳钢最终处于钝化状态，表面未观察到明显腐蚀。在含SO42-的除氧重碳酸盐缓冲溶液中，低碳钢均发生均匀腐蚀。在含有Cl-的除氧重碳酸盐缓冲溶液中，Cl-破坏了低碳钢的钝化状态。在含有SO42-和Cl-的除氧重碳酸盐缓冲溶液中，SO42-浓度越高，低碳钢均匀腐蚀特征越明显；Cl-浓度越高，低碳钢局部腐蚀特征越明显。 XRD结果显示，低碳钢在除氧重碳酸盐缓冲溶液中的腐蚀产物主要由Fe3O4和α-FeOOH组成。根据低碳钢腐蚀电位随时间变化的监测结果可知，电化学加速腐蚀方法可以用于模拟和评定裸低碳钢的长期腐蚀演化行为。"
其他摘要	"In this thesis, the corrosion behaviors of the materials for the HLW metal container are studied. The study in corrosion susceptibility of the alloy C22 to under-deposit corrosion and crevice corrosion in the simulated Yucca Mountain repository condition was conducted. In the experiment, it was found that high-density H+ formed due to the hydrolyzation of Mg2+ during the test. This resulted in the acidic of the solution and the deposit shell forming on the surface of the sample. The XRD results indicates that the deposit shell is Mg2(OH) 3Cl. Furthermore, the results revealed that the under-deposit corrosion and the crevice corrosion occurred when the alloy C22 was subject to the simulated wet-dry cyclic condition. The effect of the pH value and anions on the active/passive state of the low carbon steel was investigated by simulating the ground water condition in Beishan by borate buffer solution and bicarbonate buffer solution. When pH=8, the corrosion potential of the low carbon steel was not influenced by the corrosion products, keeping in the range of the active region, while the corrosion potential changed into the passive region when pH=9 and 10. XRD results reveal that the corrosion products of the low carbon steel in the deaerated borate buffer solution consist of Fe6 (OH)12B4O7 and γ-FeOOH. It was found that the low carbon steel maintained in the passive state and no obvious corrosion was observed in the deaerated bicarbonate buffer solution with [HCO3-]=0.1 mol/L. The SO42- in the deaerated bicarbonate buffer solution would break this passive state with the occurrence of the general corrosion. The higher concentration of SO42- means the lower corrosion potential is，and the shorter time of the open potential sharply increasing cost. Corrosion controlled by limiting diffusion current was observed on the low carbon steel in the deaerated bicarbonate buffer solution containing 0.01and 0.02 mol/L Na2SO4, transpassive corrosion was observed in the deaerated bicarbonate buffer solution when 0.5 mol/L >[SO42-]> 0.02 mol/L, and active corrosion occurred in the deaerated bicarbonate buffer solution with 0.5 mol/L Na2SO4. The Cl- in the in the deaerated bicarbonate buffer solution also broke the passive state of the low carbon steel. When [Cl-] ≤0.02 mol/L, general corrosion controlled by limiting diffusion current was observed and no obvious local corrosion happened. In contrast, when 0.05 mol/L≤ [Cl-] ≤0.2 mol/L, the serious local corrosion was observed. When 0.5 mol/L≤ [Cl-], re-active corrosion occurred on the low carbon steel surface. It is shown that the higher concentration of Cl- leads to the lower corrosion potential. In different deaerated bicarbonate buffer solutions with constant [SO42-]+[Cl-]=0.1 mol/L, the corrosion happened to the low carbon steel in all the cases. With the higher concentration of Cl-, the local corrosion is more obvious, while with higher concentration of SO42-, the general corrosion was more obvious. XRD results show that the corrosion products of the low carbon steel in the deaerated bicarbonate buffer solution mainly consist of Fe3O4 and α-FeOOH. In addition, the electrochemical corrosion acceleration method can be used to effectively simulate and evaluate the long-term corrosion behavior of the low carbon steel based on the corrosion potential evolution of the low carbon steel."
文献类型	学位论文
条目标识符	http://ir.imr.ac.cn/handle/321006/64328
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	阳靖峰. 高放废物地质处置环境下处置罐材料的腐蚀行为[D]. 北京. 中国科学院金属研究所,2011.