IOCAS-IR
深地质环境中镀铜钢储罐的电偶腐蚀行为研究
辛宇
Subtype硕士
Thesis Advisor段继周
2022-05-19
Degree Grantor中国科学院大学
Place of Conferral中科科学院海洋研究所
Degree Discipline环境工程
Keyword电偶腐蚀,核废料储罐,铜-碳钢电偶对,深地质环境,碳糊电极
Abstract

安全有序发展滨海核电,是我国优化能源结构,确保实现双碳目标的重要措施。在发展滨海核电的同时,高放核废料的处置问题也随之而来。深地质处置法将高放核废料封装在金属储罐中,深埋于地下处置库。目前,我国核废料金属储罐的设计仍然悬而未决。镀铜钢储罐设计因造价低、加工技术成熟被广泛接纳,但该设计也存在不容忽视的缺点。当铜镀层破损,碳钢和铜会形成双金属耦合体系发生电偶腐蚀,存在加剧碳钢腐蚀的风险。因此,深地质环境下铜与碳钢电偶腐蚀行为研究尤为重要。

针对深地质环境的演变规律,本论文研究了北山地下水模拟液中,温度(20~70℃)、氧含量、阴阳极面积比等因素,对铜(T2)与碳钢(Q235)电偶腐蚀动力学的影响。通过对腐蚀产物进行表征分析,总结了铜与碳钢电偶腐蚀机理,为核废料储罐镀层失效后果分析,提供科学依据

首先,本论文通过制备TpBD-COF碳糊电极,用来快速检测溶液中的铜含量,该电极对Cu2+的检测采用差分脉冲伏安法,以峰值电流拟合线性回归方程表示为Ipc = 0.461 C 7.31×105R2 = 0.99971-200 µmol L1),检测极限为0.13 µmol L1S/N=3)。另外TpBD-COF碳糊电极具有检测的多样性,实现了溶液中对苯二酚和邻苯二酚污染物的同时检测,得出该电极由于具有良好的稳定性和重复性,具有一定的发展潜力。

其次,测量了模拟地下水中,氧含量及温度(20~70)对铜(T2)与碳钢(Q235开路电位(OCP)的影响,发现两者电位差在上述条件下均大于250 mV,说明两者具备发生电偶腐蚀的条件。通过铜(T2)的阴极极化曲线与碳钢(Q235)的阳极极化曲线相交根据混合电位理论可以得出反应速率的控制步骤为阴极控制,以及粗略预测两者发生电偶腐蚀的电压及电流。但该预测值与使用零电阻电流计(ZRA)测量得到的耦合电流密度ig存在较大差距,例如使用极化曲线相交得出两者在20℃50℃70℃时耦合电流密度ZRA测量数据的2807516。本部分内容明确了两种电偶腐蚀研究方法的区别,确定了电偶电流的测量方法。

明确电偶电流的测量方法后,本论文系统研究了氧含量、温度、面积比对铜与碳钢电偶腐蚀速率的影响,并通过SEMEDSRaman等表征方法确定腐蚀产物,提出电偶腐蚀机理。研究结果表面,深地质条件下,铜与碳钢耦合会加快碳钢的腐蚀速率。铜表面氧气的还原反应,是碳钢腐蚀速度控制步骤。有氧条件下,铜与碳钢电偶电流密度随阴阳面积比增加线性增大;缺氧条件下,面积比对电偶电流密度的影响减小。有氧条件下,温度升高使电偶电流增加;缺氧条件下,温度对电偶电流密度的影响减小。有氧条件下,腐蚀产物是铁氧化物和羟基铁氧化物的混合物;缺氧条件下腐蚀产物多为羟基铁氧化物。在对碳钢表面腐蚀产物鉴定时发现了铜元素,通过盐桥实验证实铜作为电偶腐蚀中的阴极,表面也发生了阳极反应。通过碳糊电极对溶液中铜含量进行检测,确定了铜作为电偶腐蚀的阴极,表面也会发生氧化反应,并且部分铜的腐蚀产物经溶液扩散传输至碳钢表面。

Other Abstract

The safe and orderly development of Binhai nuclear power is an important measure for our country to optimize the energy structure and ensure the realization of the "dual carbon" goal. At the same time as the development of Binhai nuclear power, the disposal of high-level nuclear waste also comes with it. The deep geological disposal method encapsulates high-level radioactive nuclear waste in a metal container and buries it in an underground repository. At present, the design of the metal container for nuclear waste in our country is still pending. The design of the copper-steel container is widely accepted due to its low cost and mature processing technology, but this design also has shortcomings that cannot be ignored. When the copper coating is damaged, carbon steel and copper will form a bimetallic coupling system and cause galvanic corrosion, which has the risk of aggravating carbon steel corrosion. Therefore, it is particularly important to study the galvanic corrosion behavior of copper and carbon steel in deep geological environment.

According to the evolution discipline of deep geological environment, this paper studies the influence of temperature (20~70℃), oxygen content and area ratio of cathode and anode on the galvanic corrosion of copper (T2) and carbon steel (Q235) in Beishan groundwater simulated solution. Through the characterization and analysis of the corrosion products, the mechanism of galvanic corrosion of copper and carbon steel is summarized, which provides a scientific basis for the analysis of the failure consequences of nuclear waste containers.

Firstly, in this paper, a TpBD-COF carbon paste electrode is prepared to rapidly detect the copper content in the solution. The detection of Cu2+ by this electrode adopts differential pulse voltammetry, and the peak current is used to fit the linear regression equation, which can be expressed as Ipc = 0.461 C 7.31×105 (R2 = 0.9997, 1-200 µmol L1), the detection limit is 0.13 µmol L−1 (S/N=3). In addition, the TpBD-COF carbon paste electrode has the diversity of detection, and realizes the simultaneous detection of hydroquinone and catechol pollutants in the solution. It is concluded that the electrode has a certain development due to its good stability and repeatability potential.

Secondlythis paper measured the influence of oxygen content and temperature (20~70℃) on the open circuit potential (OCP) of copper (T2) and carbon steel (Q235) in simulated groundwater, the results showed that the potential difference between the copper (T2) and carbon steel (Q235) is greater than 250 mV, indicating that copper (T2) and carbon steel (Q235) have the conditions for galvanic corrosion. By intersecting the cathodic polarisation curve of copper (T2) with the anodic polarisation curve of carbon steel (Q235), the control step of the reaction rate can be derived as cathodic control based on mixed potential theory, as well as the voltage and current of galvanic corrosion can be roughly predicted. However, there was a large difference between the predicted value and the coupling current density ig measured by the zero resistance galvanometer (ZRA), for example, the coupling For example, using the intersection of polarization curves, the coupling current densities at 20°C, 50°C and 70°C were 280 times, 75 times and 16 times higher than those measured by ZRA. The content of this part clarifies the differences between the two methods of studying galvanic corrosion and the method of accurately measuring the galvanic corrosion current.

After clarifying the measurement method of galvanic corrosion current, the influence of oxygen content, temperature and area ratio on the galvanic corrosion rate of copper and carbon steel was systematically studied in this paper, and the corrosion products were determined by SEM, EDS and Raman characterization methods and the galvanic corrosion products mechanism were proposed. The results show that the coupling of copper and carbon steel will accelerate the corrosion rate of carbon steel under deep geological conditions. The reduction reaction of oxygen on the copper surface is the driving force for the corrosion of carbon steel. In the oxic conditions, the galvanic corrosion current density of copper and carbon steel increases linearly with the increase of the area ratio; in the anoxic conditions, the effect of area radio on the galvanic corrosion current density decreases. In the oxic conditions, the increase of temperature increases the galvanic corrosion current; In the anoxic conditions, the effect of temperature on the galvanic corrosion current density decreases. In the oxic conditions, the corrosion products are a mixture of iron oxides and ferric hydroxide oxides; In the anoxic conditions, the corrosion products are mostly ferric hydroxide oxides. Copper was found during the identification of corrosion products on the surface of carbon steel. It was confirmed by salt bridge experiments that copper was used as a cathode in galvanic corrosion, and an anodic reaction also occurred on the surface. The copper content in the solution was detected by carbon paste electrode, and the copper was determined as the cathode of galvanic corrosion, and the oxidation reaction occurred on the surface, and part of the copper corrosion products were diffused and transferred to the surface of carbon steel.

Language中文
Table of Contents

第一章 绪论 1

1.1 研究背景 1

1.2 核废料深地质处置国内外研究进展 3

1.2.1国外研究现状 3

1.2.2 国内研究现状 3

1.3 深地质腐蚀环境 5

1.3.1 核储罐温度演变规律 5

1.3.2 深地质环境中氧含量变化 6

1.3.3 深地质处置环境中地下水溶液 7

1.4 关于核废料储罐耐蚀性能研究 8

1.4.1 核废料储罐候选材料选择 8

1.4.2 核废料储罐候选材料耐蚀性能研究 10

1.5 深地质腐蚀环境铜和碳钢的电偶腐蚀 11

1.6 选题依据及研究内容 13

1.6.1 选题依据 13

1.6.2 研究内容 14

第二章 碳糊电极法检测溶液中的铜离子 15

2.1 引言 15

2.2 实验部分 16

2.2.1 材料与试剂 16

2.2.2 TpBD-COF和工作电极的制备 16

2.2.3 铜离子检测实验方法 18

2.3 结果与讨论 19

2.3.1 电极优化 19

2.3.1.1 电极导电性 19

2.3.1.2 电极对Cu2+的循环伏安响应 20

2.3.1.3 电极配比优化 21

2.3.1.4 电极反应pH优化 21

2.3.2 电极对Cu2+标准曲线的测定 22

2.3.3 电极性能测试 23

2.3.4 模拟地下水溶液中Cu2+检测 23

2.3.5 电极检测的多样性 24

2.4 本章小结 28

第三章 碳钢在深地质环境中的腐蚀规律和电偶腐蚀监测方法 29

3.1 引言 29

3.2 实验部分 29

3.2.1 材料与试剂 29

3.2.2 工作电极的制备 31

3.2.3 甘肃北山地区地下水模拟液 31

3.2.3 实验装置及预除氧实验 32

3.2.4 Q235碳钢和T2铜电化学腐蚀实验方法 33

3.3 结果与讨论 34

3.3.1 有氧条件下Q235碳钢在不同温度下的腐蚀行为 34

3.3.2 缺氧条件下Q235碳钢在不同温度下的腐蚀行为 36

3.3.3 碳钢和铜电偶腐蚀热力学依据 39

3.3.4 碳钢和铜电偶腐蚀的研究方法 41

3.4 本章小结 43

第四章 铜和碳钢耦连后在深地质地下水模拟溶液中的电偶腐蚀 45

4.1 引言 45

4.2 实验部分 45

4.2.1 材料与试剂 45

4.2.2 工作电极的制备 46

4.2.3 实验装置及预除氧实验 46

4.2.4 T2铜和Q235碳钢耦连电偶腐蚀实验方法 47

4.2.5 T2铜和Q235碳钢耦连电偶腐蚀产物表征 47

4.3 结果与讨论 48

4.3.1 氧含量对铜-碳钢电偶腐蚀的影响 48

4.3.2 面积比对铜和碳钢电偶腐蚀的影响 51

4.3.3 温度对铜和碳钢电偶腐蚀的影响 53

4.3.4 腐蚀产物分析 55

3.3.5 利用盐桥进行铜和碳钢耦合实验 60

4.3.6 金属铜电极腐蚀检测 61

4.4 本章小结 62

第五章 结论与展望 65

5.1 结论 65

5.2 展望 66

参考文献 67

75

作者简历及攻读学位期间发表的学术论文与研究成果 77

Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/178401
Collection中国科学院海洋研究所
Recommended Citation
GB/T 7714
辛宇. 深地质环境中镀铜钢储罐的电偶腐蚀行为研究[D]. 中科科学院海洋研究所. 中国科学院大学,2022.
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