海洋环境腐蚀与生物污损重点实验室知识库

低合金高强度钢具有节约资源、降低建设成本等优点，但对氢脆敏感。在海洋环境中，不恰当的阴极保护电位会促进氢向钢中渗透，增大发生氢脆的可能性。如果能利用自然界中广泛存在的耗氢微生物消耗阴极保护过程中产生的氢，抑制氢的渗透，就可以适当降低阴极保护电位，在不增加氢脆风险的基础上，实现对高强度钢的完全保护。

本论文研究了耗氢微生物（Blautia coccoides GA-1）对AISI 4135钢腐蚀行为的影响。结果表明，菌株GA-1可以从AISI 4135钢表面直接或间接获得电子，最大电流密度约为−1.54 μA/cm²，但该过程不是导致钢加速腐蚀的主要原因。自腐蚀电位下，AISI 4135钢的腐蚀速度与菌株GA-1的菌量成正相关。

研究了菌株GA-1对AISI 4135钢氢渗透行为的影响，通过氢渗透效率（η）对微生物的耗氢作用进行表征。结果表明，附着于金属表面的菌株GA-1细胞可以直接从阴极表面附近获得新产生的氢原子[H]，并降低表面吸附氢浓度。从而减少了氢的吸收比例并导致氢渗透效率降低。−0.85V vs. SCE极化电位下，菌株GA-1可降低氢渗透效率约9%。过负的阴极保护电位（−1.05V vs. SCE），会抑制了菌株GA-1细胞的附着，使其在氢消耗作用较弱，氢渗透效率基本不变。在较小的恒电流（−3 μA/cm²）极化条件下，菌株GA-1可以有效的消耗阴极氢，从而降低氢渗透电流，8 d内的氢渗透量增加量仅为0.47×10⁻⁶ mol/cm²。

利用慢应变速率拉伸试验（SSRT）研究了AISI 4135钢的应力腐蚀破裂敏感性。结果表明，阴极极化和菌株GA-1的存在均可增加AISI 4135钢氢脆敏感性（I_scc）。I_scc均比自腐蚀电位下增加40%以上。尽管菌株GA-1具有消耗阴极氢的作用，降低了氢渗透效率，但同样由于其副作用的存在，导致了AISI 4135钢表观氢脆敏感性的增强。因此，在增强耗氢微生物消耗阴极氢的作用的同时，减弱微生物存在所带来的副作用是将来利用耗氢微生物进行氢脆抑制切实可行的关键。

本论文系统研究了耗氢微生物对高强度钢阴极保护过程中腐蚀行为、氢渗透行为以及力学行为的作用规律与机理，分析了利用耗氢微生物抑制高强度钢氢脆的可行性，这一目标的实现对高强度钢在海洋环境中的安全应用有十分重要的意义，有广阔的应用前景。

High-strength low-alloy (HSLA) steels have the advantages of save resources and reduce costs, but it is susceptible to hydrogen embrittlement (HE). In marine environments, inappropriate cathodic potentials will promote the hydrogen penetrate into steel and lead to HE. If we can utilize the hydrogen consuming microorganisms to consume the hydrogen generated in the process of cathode protection, reducing the amount of hydrogen’s penetrating into material, then the potential can be reasonably lowered, making the steel ideally protected to a minimum corrosion rate and reducing the possibility of HE’s occurring at the same time.

The corrosion behavior of AISI 4135 steel in the presence of hydrogen consuming microorganisms (Blautia coccoides GA-1) was studied in this paper. The results show that strain GA-1 could directly or indirectly obtain electrons from AISI 4135 steel with the maximum current density of −1.54 μA/cm² which was not the primary reason leading to the increase of corrosion current. The corrosion rate was positively related to the number of strain cells under free corrosion potential.

The hydrogen permeation behavior of AISI 4135 steel in the presence of strain GA-1 was studied and the hydrogen consuming ability of strain GA-1 was characterized by hydrogen permeation efficiency (η). The results show that the adherent strain GA-1 cells could obtain the newly generated [H] directly from the vicinity of the cathode surface and reducing the hydrogen concentration and decreasing the η. Strain GA-1 could reduce the η by about 9% under −0.85V vs. SCE polarization potential. A more negative cathodic potential (−1.05V vs. SCE) inhibits strain GA-1’s attaching to the cathode surface, leading to weaker hydrogen consumption effects and the η was basically unchanged. Strain GA-1 can effectively consume cathodic hydrogen and decrease hydrogen permeation current when a smaller constant polarization current (−3 μA/cm²) was applied. The increased total hydrogen permeation in 8 d was only 0.47×10⁻⁶ mol/cm².

The stress corrosion cracking (SCC) susceptibility was measured by slow strain rate test (SSRT). The results show that both cathode protection and strain GA-1 can increase the HE susceptibility (I_scc) of AISI 4135 steel. I_scc increased by more than 40% compared with the free corrosion potential conditions.

Although the strain GA-1 can consuming cathodic hydrogen and reducing the η, the apparent HE susceptibility of AISI 4135 steel is also increased due to its side effects. Therefore, the key to inhibiting HE is to enhance the effect of consuming cathode hydrogen and reduce the side effects of strain GA-1.

The corrosion, hydrogen permeation and mechanical behavior of AISI 4135 steel in the presence of hydrogen consuming microorganisms was studied systematically in this project. The feasibility of using hydrogen consuming microorganisms to inhibit hydrogen embrittlement of HLSA steel was analyzed. The realization of this method is of great significance for the safe application of HLSA steel in marine environments, having broad application prospects.

第1章  绪论.................................................................................. 1

1.1  研究背景及意义.................................................................. 1

1.2  氢与金属间的相互作用...................................................... 2

1.2.1  氢的来源及渗入........................................................ 2

1.2.2  氢在金属中的溶解和扩散........................................ 5

1.2.3  氢陷阱........................................................................ 6

1.2.4  氢脆............................................................................ 8

1.2.5  氢脆机理.................................................................... 9

1.2.6  金属内氢的检测...................................................... 11

1.3  阴极保护............................................................................ 13

1.3.1  阴极保护分类.......................................................... 13

1.3.2  阴极保护准则.......................................................... 14

1.3.3  阴极保护下高强度钢氢脆研究进展...................... 14

1.4  微生物腐蚀........................................................................ 16

1.4.1  微生物腐蚀简介...................................................... 16

1.4.2  微生物腐蚀机理...................................................... 16

1.4.3  微生物对高强度钢氢脆影响研究进展.................. 17

1.5  本文的主要研究内容........................................................ 18

第2章  耗氢微生物对高强度钢腐蚀行为及阴极极化的影响................................................................................................... 21

2.1  引言.................................................................................... 21

2.2  材料与方法........................................................................ 23

2.2.1  耗氢微生物获取及培养.......................................... 23

2.2.2  耗氢微生物表征...................................................... 26

2.2.3  电化学实验材料...................................................... 27

2.2.4  电化学实验装置及测试.......................................... 27

2.3  结果与讨论........................................................................ 30

2.3.1  菌落及细胞形态学观察.......................................... 30

2.3.2  菌株GA-1生长曲线............................................... 32

2.3.3  开路电位.................................................................. 34

2.3.4  计时电流法.............................................................. 35

2.3.5  线性极化电阻.......................................................... 38

2.3.6  电化学阻抗谱.......................................................... 39

2.3.7  阴极极化曲线.......................................................... 43

2.4  本章小结............................................................................ 46

第3章  耗氢微生物对高强度钢氢渗透行为的影响..... 49

3.1  引言.................................................................................... 49

3.2  材料与方法........................................................................ 50

3.2.1  实验材料.................................................................. 50

3.2.2  实验装置及方法...................................................... 51

3.2.3  表面分析.................................................................. 52

3.3  结果与讨论........................................................................ 53

3.3.1  菌株GA-1在氢渗透装置内的生长曲线............... 53

3.3.2  自腐蚀电位下的氢渗透电流.................................. 53

3.3.3  恒电位极化对氢渗透行为的影响.......................... 55

3.3.4  恒电流极化对氢渗透行为的影响.......................... 72

3.3.5  菌株GA-1耗氢模型............................................... 78

3.4  本章小结............................................................................ 79

第4章  耗氢微生物对高强度钢应力腐蚀开裂敏感性的影响................................................................................................... 81

4.1  引言.................................................................................... 81

4.2  材料与方法........................................................................ 81

4.2.1  实验材料.................................................................. 81

4.2.2  实验装置.................................................................. 83

4.2.3  实验步骤.................................................................. 84

4.3  结果与讨论........................................................................ 85

4.3.1  无菌培养基中的SSRT实验................................... 85

4.3.2  菌株GA-1培养基中的SSRT实验........................ 92

4.3.3  SCC敏感性分析...................................................... 98

4.4  本章小结.......................................................................... 100

第5章  耗氢微生物对高强度钢氢脆抑制可行性分析.......................................................................................................... 101

5.1  引言.................................................................................. 101

5.2  菌株GA-1特征............................................................... 101

5.3  自腐蚀电位下的影响...................................................... 101

5.4  阴极极化下菌株GA-1的影响....................................... 102

5.5  本章小结.......................................................................... 104

第6章  结论与展望................................................................ 105

6.1  结论.................................................................................. 105

6.2  创新点.............................................................................. 106

6.3  展望.................................................................................. 107

参考文献....................................................................................... 109

附  录............................................................................................ 121

致  谢............................................................................................ 123

作者简历及攻读学位期间发表的学术论文与研究成果    125