【作者】 刘丹；

【导师】 杨洪英；

【作者基本信息】 东北大学 ， 有色金属冶金， 2019， 博士

【摘要】 海洋环境中金属材料的微生物腐蚀是海洋工程材料的一大威胁,既会造成巨大经济损失,也存在难以估摸的安全隐患。因此研究海洋环境常用金属材料在各种常见微生物环境中的腐蚀行为、探索微生物腐蚀的发生机理,对于总结其腐蚀规律具有辅助意义,也对材料的防护具有重要意义,最终通过指导新材料的设计研究和开发来更好实现抑制微生物腐蚀。本文选取了海洋环境中常用的耐蚀金属材料TC4钛合金、2205双相不锈钢(Duplex Stainless Steel,DSS)以及 316L 不锈钢(Stainless Steel,SS),分别采用电化学测试、形貌表征和腐蚀产物分析等方法研究了材料在电活性细菌Pseudomonas aeruginosa、Shewanella algae及产酸菌Acetobacter aceti环境中的微生物腐蚀行为,并探究了可能发生的腐蚀机理;针对这几种细菌所造成的微生物腐蚀,采用新型含铜抗菌材料,研究材料的抗菌性能及耐微生物腐蚀性能,分析其抗菌和耐蚀机理。(1)TC4钛合金在P.aeruginosa环境中的腐蚀电位比无菌环境下更负,腐蚀倾向更大,腐蚀速率增大,P.aeruginosa分泌的内生性电子载体PCN促进了 TiO2的还原,生成稳定性较差的Ti2O3,在Cl-的协同作用下促进了 TC4钛合金点蚀的发生。敲除和回补基因的突变体P.aeruginosa从基因水平证明了胞外电子传递(Extracellular Electron Transfer,EET)是促进TC4钛合金发生腐蚀的主要原因,腐蚀类型为EET-MIC;(2)细菌S.algae对2205 DSS造成较为严重的腐蚀。电化学测试结果表明2205 DSS在S.algae中腐蚀电位负移,腐蚀速率明显增大。因为S.algae是常见的传电型细菌,其分泌产生的电子载体——核黄素促进了 2205 DSS和细菌之间的电子转移,加速了 2205 DSS的腐蚀,其腐蚀类型属于传电型腐蚀;(3)对比研究了 2205 DSS在无菌环境和产酸菌A.aceti环境下的电化学腐蚀行为,结果发现2205 DSS在A.aceti环境下电位更负,且腐蚀速率更大。A.aceti代谢产生具有腐蚀性的乙酸,使得2205 DSS的钝化膜被破坏,促进点蚀发生,腐蚀产物以Cr2O3、CrO3及铁的氧化物为主,A.aceti对2205 DSS的腐蚀属于典型的代谢产物腐蚀;(4)采用电化学测试对比研究了 316L SS在无菌和A.aceti环境下的腐蚀行为,结果表明,在A.aceti环境中,316LSS的腐蚀电位负移,线性极化电阻、电化学阻抗谱和极化曲线等电化学方法测得316L SS在A.aceti环境中腐蚀速率明显增大,腐蚀产物分析表明,腐蚀产物以Cr和Fe的氧化物为主,可溶解的CrO3产生是点蚀进一步发生的主要原因;(5)2205-Cu DSS对电活性细菌S.algae的抗菌作用明显,且能有效抑制S.algae引起的腐蚀。电化学测试结果表明,2205-Cu DSS的腐蚀速率明显小于2205DSS,点蚀坑深度小于2205DSS;AAS检测结果表明,溶液中有一定量的铜离子分布,是来自于材料基体的铜元素溶解,细菌和生物被膜形貌观察结果表明,死亡细菌显著增多,2205-Cu DSS溶出的Cu离子很好抑制了S.algae在材料表面的覆盖,2205-Cu DSS的接触式杀菌以及溶液中的铜离子对S.algae具有很好的杀灭作用,从而有效抑制了S.algae引起的腐蚀;(6)借助扫描电子显微镜、激光共聚焦显微镜等手段考察了 2205-Cu DSS对产酸菌A.aceti的抗菌性能,并采用电化学测试的方法研究了 2205-Cu DSS的耐蚀性能,结果表明,2205-Cu DSS表面的细菌和生物被膜明显减少,死亡细菌显著增多,表现出良好的抗菌性;电化学测试结果表明,2205-Cu DSS腐蚀速率明显小于2205 DSS,点蚀坑深度也小于2205 DSS,2205-Cu DSS很好抑制了 A.aceti引起的腐蚀;材料基体中弥散分布的铜元素有效溶出,使其具有良好的抗菌性能,很好抑制产酸菌A.aceti引起的腐蚀;(7)考察了 316L-Cu SS在产酸菌A.aceti环境下的抗菌特性和耐微生物腐蚀性能,结果表明,316L-Cu SS很好抑制了表面和溶液中A.aceti的生长,抗菌作用明显,且腐蚀速率明显小于316L SS,点蚀坑深度也小于316LSS,很好抑制了产酸菌A.aceti引起的腐蚀。更多还原

【Abstract】 Microbiologically influenced corrosion(MIC)is a big threat to the reliability of marine engineering materials,causing severe economic losses and unpredictable safety hazards.Therefore,it is important to study the MIC behavior and mechanism of different metallic materials in marine environment using common marine microorganisms.MIC inhibition could be achieved by using different corrosion protection techniques and the development of corrosion resistant materials.In the present study,different corrosion-resistant metallic materials TC4 titanium alloy,2205 duplex stainless steel(DSS)and 316L stainless steel(SS)which are commonly used in marine environment were selected.Electrochemical tests,surface analytical techniques and corrosion product analysis were performed to study their MIC behavior and mechanism in the presence of acid-producing bacteria A.aceti,P.aeruginosa and S.algae,respectively.Copper-containing antibacterial materials were adopted to study the antibacterial property and corrosion resistance of the materials.(1)The corrosion potential of TC4 titanium alloy was more negative in P.aeruginosa broth than that in the sterile medium,indicating a greater corrosion tendency.Moreover,the corrosion rate of TC4 titanium alloy in biotic medium increased.The endogenous electron carrier PCN might promoted electron transfer,accelerating the reduction of TiO2.The nonstable sub-oxides(Ti2O3)encouraged the occurrence of pitting corrosion on TC4 surface.The corrosion type is extracellular electron transfer-MIC(EET-MIC).(2)S.algae caused severe corrosion to 2205 DSS.Electrochemical results showed that the corrosion potential of 2205 DSS is negatively shifted in the presence of S.algae,and corrosion rate is significantly increased.The electron carrier riboflavin which was secreted by S.algae promoted electron transfer between 2205 DSS and bacteria,accelerating the corrosion of 2205 DSS.Corrosion type caused by S.algae belongs to EET-MIC.(3)Electrochemical techniques were used to study the corrosion behavior of 2205 DSS in the presence of marine bacterium A.aceti.It was found that 2205 DSS having lower corrosion potential and higher corrosion rate in the presence of A.aceti.A.aceti secretes corrosive acetic acid,which destroyed the passive film on the surface of 2205 DSS,causing pitting corrosion.Cr2O3,CrO3 and iron oxides were detected during the analysis of corrosion products using XPS.The corrosion of 2205 DSS caused by A.aceti belongs to MetaboliteMIC(M-MIC).(4)Corrosion behavior of 316L stainless steel was studied in the presence of A.aceti by using electrochemical test.The results showed decrease in the corrosion potential of 316L SS in the A.aceti broth compared to that in the abiotic medium.Corrosion rate of 316L SS studied by linear polarization resistance,electrochemical impedance spectroscopy and polarization curve increased significantly in the biotic broth.Oxides of Cr and Fe were the main components of corrosion products.The pitting corrosion was attributed to dissolution of soluble CrO3.(5)Antibacterial effect of 2205-Cu DSS against S.algae was remarkable.MIC caused by S.algae was effectively inhibited by 2205-Cu DSS.Results of electrochemical test showed that the corrosion rate of 2205-Cu DSS was very low compared to the 2205 DSS.In addition,the pit depth detected on the surface of 2205-Cu DSS was less than 2205 DSS.AAS result showed the distribution of certain amount of copper ions in the solution,which resulted from the dissolution of copper from the material matrix.The analysis of biofilm morphology showed high number of dead bacterial cells on the material surface,demonstrating the inhibition of S.algae biofilm on the surface of 2205-Cu DSS.It was confirmed from this study that 2205-Cu DSS possesses excellent antibacterial properties.Cu2+released from 2205-Cu DSS matrix inhibited the biofilm formation on the metal surface,thus leading to effective mitigation of MIC caused by S.algae.(6)The antibacterial properties of 2205-Cu DSS against acid-producing bacteria A.aceti were investigated by means of scanning electron microscopy and laser confocal microscopy.The corrosion resistance of 2205-Cu DSS was studied using electrochemical test.The results showed decrease in the number of bacteria and biofilms on the surface of 2205-Cu DSS.The number of dead bacterial cells was increased significantly,showing good antibacterial properties of 2205-Cu DSS;results of electrochemical test showed that corrosion rate of 2205-Cu DSS decreased significantly compared to 2205 DSS.The pit depth detected on 2205-Cu DSS surface was smaller than 2205 DSS.The good antibacterial properties of 2205Cu DSS was attributed to the dispersion of copper in the matrix of the material,thus inhibiting the corrosion caused by A.aceti.(7)The antibacterial properties and microbial corrosion resistance of 316L-Cu SS against MIC caused by A.aceti were investigated by surface analytical techniques and electrochemical tests.The results showed that 316L-Cu SS inhibited the growth and activity of A.aceti which decreased the corrosion rate of 316L-Cu SS compared to 316L SS.Corrosion of 316L-Cu SS caused by A.aceti was inhibited effectively.更多还原