Electron transfer mediator PCN secreted by aerobic marine Pseudomonas aeruginosa accelerates microbiologically influenced corrosion of TC4 titanium alloy

Titanium alloys possess excellent corrosion resistance in marine environments,thus the possibility of their corrosion caused by marine microorganisms is neglected.In this work,microbiologically influenced corrosion (MIC) of TC4 titanium alloy caused by marine Pseudomonas aeruginosa was investigated through electrochemical and surface characterizations during a 14-day immersion test.Results revealed that the unstable surface caused by P.aeruginosa resulted in exposure of Ti2O3 and severe pitting corrosion with maximum pit depth of 5.7 μm after 14 days of incubation.Phenazine-1-carboxy[ate (PCN),secreted by P.aeruginosa,promoted extracellular electron transfer (EET) and accelerated corrosion.Deletion of the phzH gene,which codes for the enzyme that catalyzes PCN production,from the P.aeruginosa genome,resulted in significantly decreased rates of corrosion.These results demonstrate that TC4 titanium alloy is not immune to marine MIC,and EET contributes to the corrosion of TC4 titanium alloy caused by P.aeruginosa.     

Enhanced resistance of 2205 Cu-bearing duplex stainless steel towards microbiologically influenced corrosion by marine aerobic Pseudomonas aeruginosa biofilms

An antibacterial 2205-Cu duplex stainless steel(DSS)was shown to inhibit the formation and growth of corrosive marine biofilms by direct contact with copper-rich phases and the release of Cu~(2+)ions from the2205-Cu DSS surface.In this work,the microbiologically influenced corrosion(MIC)resistance of 2205-Cu DSS in the presence of the corrosive marine bacterium Pseudomonas aeruginosa was investigated.The addition of copper improved the mechanical properties such as the yield strength,the tensile strength and the hardness of 2205 DSS.Electrochemical test results from linear polarization resistance(LPR),electrochemical impedance spectroscopy(EIS)and critical pitting temperature(CPT)measurements showed that 2205-Cu DSS possessed a larger polarization resistance(R_p),charge transfer resistance(R_(ct))and CPT values,indicating the excellent MIC resistance of 2205-Cu DSS against the corrosive P.aeruginosa biofilm.The live/dead staining results and the SEM images of biofilm confirmed the strong antibacterial ability of 2205-Cu DSS.The largest pit depth of 2205-Cu DSS was considerably smaller than that of 2205 DSS after 14 d in the presence of P.aeruginosa(2.2μm vs 12.5μm).2205-Cu DSS possessed a superior MIC resistance to regular 2205 DSS in the presence of aerobic P.aeruginosa.     

Biofilm inhibition and corrosion resistance of 2205-Cu duplex stainless steel against acid producing bacterium Acetobacter aceti

Acid producing bacterium Acetobacter aceti causes pitting corrosion of stainless steel(SS).This work investigated the enhanced resistance of 2205-Cu duplex stainless steel(DSS) against biocorrosion by A.aceti in comparison with 2205 DSS using electrochemical and surface analysis techniques.With the addition of Cu to 2205 DSS,biofilms on the 2205-Cu DSS surface were inhibited effectively.The largest pit depth on 2205-Cu DSS surface in the presence of A aceti was 2.6 μm,smaller than 5.5 μm for 2205 DSS surface.The i_(corr) was 0.42±0.03 μA cm~(-2) for 2205-Cu DSS in the biotic medium,which was much lower than that for 2205 DSS(3.69±0.65 μA cm~(-2)).All the results indicated that the A aceti biofilm was considerably inhibited by the release of Cu~(2+) ions from the 2205-Cu DSS matrix,resulting in the mitigation of biocorrosion by A aceti.     

Tribocorrosion behavior in artificial seawater and anti-microbiologically influenced corrosion properties of TiSiN-Cu coating on F690 steel

The TiSiN-Cu nanocomposite coating was deposited on F690 steel substrate by arc ion plating. The structure and composition, tribocorrosion behavior and anti-microbiologically influenced corrosion (MIC) properties of TiSiN-Cu coating were investigated. The results show that the TiSiN-Cu coating has unique nanocomposite structures. The results of tribocorrosion show that the potential and current change of F690 steel and TiSiN-Cu coatings tend to be opposite. The reason is that the F690 steel is non-passivated metal and the TiSiN-Cu coating has passivation phenomenon. The TiSiN-Cu coating possesses excellent tribocorrosion resistance. Cu ion released from TiSiN-Cu coating can effectively inhibit the corrosion caused by SRB.     

Microbiologically influenced corrosion behavior of S32654 super austenitic stainless steel in the presence of marine Pseudomonas aeruginosa biofilm

S32654 super austenitic stainless steel(SASS) is widely used in highly corrosive environments. However,its microbiologically influenced corrosion(MIC) behavior has not been reported yet. In this study, the corrosion behavior of S32654 SASS caused by a corrosive marine bacterium Pseudomonas aeruginosa was investigated using electrochemical measurements and surface analysis techniques. It was found that P. aeruginosa biofilm accelerated the corrosion rate of S325654 SASS, which was demonstrated by a negative shift of the open circuit potential(EOCP), a decrease of polarization resistance and an increase of corrosion current density in the culture medium. The largest pit depth of the coupons exposed in the P.aeruginosa broth for 14 days was 2.83 m, much deeper than that of the control(1.33 m) in the abiotic culture medium. It was likely that the P. aeruginosa biofilm catalyzed the formation of CrO_3, which was detrimental to the passive film, resulting in MIC pitting corrosion.     

Anaerobic microbiologically influenced corrosion mechanisms interpreted using bioenergetics and bioelectrochemistry: A review

Microbiologically influenced corrosion (MIC) is a major cause of corrosion damages, facility failures, and financial losses, making MIC an important research topic. Due to complex microbiological activities and a lack of deep understanding of the interactions between biofilms and metal surfaces, MIC occurrences and mechanisms are difficult to predict and interpret. Many theories and mechanisms have been proposed to explain MIC. In this review, the mechanisms of MIC are discussed using bioenergetics, microbial respiration types, and biofilm extracellular electron transfer (EET). Two main MIC types, namely EET-MIC and metabolite MIC (M-MIC), are discussed. This brief review provides a state of the art insight into MIC mechanisms and it helps the diagnosis and prediction of occurrences of MIC under anaerobic conditions in the oil and gas industry.     

Microbial corrosion resistance of a novel Cu-bearing pipeline steel

Microbiologically influenced corrosion (MIC) is becoming a serious problem for buried pipelines. Developing environmentally friendly strategies for MIC control is increasingly urgent in oil/gas pipeline industry. Copper (Cu) in steels can not only provide aging precipitation strengthening, but also kill bacterium, offering a special biofunction to steels. Based on the chemical composition of traditional X80 pipeline steel, two Cu-bearing pipeline steels (1% Cu and 2% Cu) were fabricated in this study. The microstructure, mechanical properties and antibacterial property against sulphate-reducing bacteria (SRB) and Pseudomonas aeruginosa (P. aeruginosa) were studied. It was found that the novel pipeline steel alloyed by 1%Cu exhibited acicular ferrite microstructure with nano-sized Cu-rich precipitates distribution in the matrix, resulting in better mechanical properties than the traditional X80 steel, and showed good MIC resistance as well. The pitting corrosion resistance of 1% Cu steel in as-aged condition was significantly better than that of X80 steel. A possible antibacterial mechanism of the Cu-bearing pipeline steel was proposed.     

The effect of Pseudoxanthomonas sp. as manganese oxidizing bacterium on the corrosion behavior of carbon steel

The present study investigated the role of manganese oxidizing bacterium (MOB), namely Pseudoxanthomonas sp. on the corrosion behavior of carbon steel. This bacterium was isolated from sewage treatment plants and identified by biochemical and molecular methods. The electrochemical techniques such as open circuit potentiometry, electrochemical impedance spectroscopy, potentiodynamic and cyclic polarization were used to measure the corrosion rate and observe the corrosion mechanism. Also, scanning electron microscopy and X-ray diffraction studies were applied to surface analysis. This study revealed the strong adhesion of the biofilm on the metal surface in the presence of Pseudoxanthomonas sp. that enhanced the corrosion of carbon steel. X-ray diffraction patterns identified a high content of MnO₂ deposition within these biofilms. This is the first report that discloses the involvement of Pseudoxanthomonas sp. as manganese oxidizing bacteria on the corrosion of carbon steel.     

Improved corrosion resistance and biofilm inhibition ability of copper-bearing 304 stainless steel against oral microaerobic Streptococcus mutans

304 stainless steel(SS) used as orthodontic wire during orthodontics faces the risk of microbiologically influenced corrosion(MIC) due to diverse flora environment. Hereinto, Streptococcus mutans(S. mutans)is the most important cariogenic bacteria. In this work, MIC behavior of a new 304-Cu SS in presence of S. mutans was studied by the observations using scanning electron microscopy(SEM) and confocal laser scanning microscopy(CLSM) including live/dead staining, extracellular polymeric substance(EPS)staining and pitting corrosion, electrochemical test, and X-ray photoelectron spectroscopy(XPS). Above results showed that 304-Cu SS possessed excellent biofilm inhibition ability and presented lower corrosion current density(icorr), larger polarization resistance(Rp) and charge transfer resistance(Rct) in the presence of S. mutans, indicating that 304-Cu SS had a better MIC resistance against S. mutans. It was further affirmed by XPS results that the presence of Cu-oxide in passive film of 304-Cu SS inhibited the formation of biofilm.     

Synergistic effect of chloride ion and Shewanella algae accelerates the corrosion of Ti-6Al-4V alloy

The increasing utilization of titanium alloys in marine environments makes their microbiologically influenced corrosion study a timely matter.This work demonstrated that the corrosion of Ti-6Al-4V alloy was accelerated by a marine bacterium Shewanella algae in 2216E medium with different Cl level.Various electrochemical,pitting morphology and passive film analyses demonstrated that S.algae weakened the passive film,which made Cl-more aggressive.The synergy of those two factors caused considerable corrosion acceleration of the titanium alloy,leading to a maximum pit depth of 3.2 μm and corrosion current density of 26.5 nA cm-2 in 2216E medium with 3.50 ％ (w/w) Cl-.     

Selective dissolution of austenite in AISI 304 stainless steel by bacterial activity

Selective attack in an AISI 304 stainless steel weld metal has been developed after three months in service in well water. Welding zones showed a severe corrosive attack that in some cases led to the steel perforation. Optical and scanning electron microscopy (SEM/EDX) revealed a selective attack. An in-depth analysis showed indications of microbiological activity which could be responsible of the severe attack.     

Constructing zwitterionic nanofiber film for anti-adhesion of marine corrosive microorganisms

A zwitterionic nanofiber film was constructed through combining zwitterionic polymer with anodic aluminum oxide template for anti-adhering typical marine corrosive microorganisms,i.e.Pseudomonas aeruginosa,Desulfovibrio vulgaris and Chaetoceros muelleri.Results showed that the fabricated zwitterionic polymers film has fibrous nanostructure with uniform distribution and super hydrophilia.This film has wide anti-adhering properties,and it can effectively reduce the attachment of these three microorganisms by more than 99％.Moreover,the adhesion of extracellular polymeric substances secreted from these three microorganisms are also inhibited,which is one reason for the fabricated nanofiber film with anti-adhesion characteristic of microorganisms.This research provides valuable information for solving the problem of microbial adhesion on metal surfaces in the marine environment.     

铜绿假单胞菌对2205双相不锈钢腐蚀行为的影响

将具有(111)择优取向的岛状奥氏体相嵌入连续铁素体的2205双相不锈钢(2205 DSS)工作面浸泡在铜绿假单胞菌(P. aeruginosa)中进行电化学测试,研究浸泡时间对2205 DSS 微生物腐蚀行为的影响。开路电位(OCP)、线性极化电阻(LPR)以及电化学阻抗谱(EIS)表明,在7 d浸泡期的无菌溶液中测得的E_OCP、极化电阻(R_p)和电荷转移电阻(R_ct)均比在有菌溶液中的大,表明铜绿假单胞菌加速了2205 DSS的腐蚀。动电位极化曲线表明,2205 DSS在无菌和有菌溶液中的维钝电流密度(i_p)都随着浸泡时间的延长而不断增大,且在浸泡1 d、3 d、7 d的每个时间点有菌溶液的i_p均比无菌环境的大,进一步证明铜绿假单胞菌加速了2205 DSS的腐蚀进程。扫描电子显微镜(SEM)结果表明,在有菌溶液中随着浸泡时间的延长表面粘附的细菌量逐渐增多,浸泡3 d后样品表面的细菌聚集成一个个小团簇,浸泡7 d菌落进一步聚集形成细菌生物膜。对腐蚀后样品表面局部腐蚀形貌的观察发现,细菌生物膜的形成加速了表面局部腐蚀的发生,导致严重的局部腐蚀。X射线光电子能谱(XPS)结果表明,在存在铜绿假单胞菌的条件下2205 DSS表面形成溶于水的CrO₃,使MIC点蚀发生。     

Microbially influenced corrosion of stainless steel by marine bacterium Vibrio natriegens: (I) Corrosion behavior

The microbially influenced corrosion of stainless steel (SS) by marine bacterium Vibrio natriegens (V. natriegens) was investigated using surface analysis (atomic force microscopy (AFM), scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA)) and electrochemical techniques (the open circuit potential, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization curves ). AFM images corroborated the results from the EIS models which show biofilm attachment and subsequent detachment over time. The SEM images revealed the occurrence of micro-pitting corrosion underneath the biofilms on the metal surface after the biofilm removal. The presence of carbon, oxygen, phosphor and sulfur obtained from EDXA proved the formation of biofilm. The electrochemical results showed that the corrosion of SS was accelerated in the presence of V. natriegens based on the decrease in the resistance of the charge transfer resistance (R_ct) obtained from EIS and the increase in corrosion current densities obtained from potentiodynamic polarization curves.     

Microbially influenced corrosion of 303 stainless steel by marine bacterium Vibrio natriegens: (II) Corrosion mechanism

Electrochemical techniques (electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves) and surface analysis (scanning electron microscopy (SEM)) were carried out to determine the possible mechanism of the microbially influenced corrosion of 303 stainless steel (303 SS) by marine bacterium Vibrio natriegens (V. natriegens). In order to clarify the mechanism, 303 SS coupons were immersed in four different mediums. EIS results were interpreted with different equivalent circuits to model the physicoelectric characteristics of the electrode/biofilm/solution interface. The results showed that N₂-fixation actually promoted the corrosion of 303 SS; however, the influence of the produced NH₃ was negligible. It can be speculated that the electron transfer and/or the nitrogenase catalyzing the process may influence the corrosion.     

Characterizations of the biomineralization film caused by marine Pseudomonas stutzeri and its mechanistic effects on X80 pipeline steel corrosion

Microbiologically influenced corrosion(MIC) of steel generates a corrosion product film,which can also be called biomineralization film.It is critical to understand the structure of biomineralization film since it dominates the corrosion behavior of metal.In this work,Pseudomonas stutzeri(P.stutzeri) was isolated from seawater,and the biomineralization film caused by marine P.stutzeri was characterized by Transmission electron microscopy(TEM),scanning electron microscopy(SEM),X-ray diffraction(X...     

氢渗透电流法监测海洋大气中钢材的腐蚀速率

用Devnathan-Stachurski双电解池技术,对16Mn钢表面干湿循环时氢渗透现象进行了研究,结果表明不同表面液膜下,都有氢渗透电流的存在.氢离子渗透量与试样腐蚀失重之间存在线性关系.利用此线性关系制作的实时监测氢渗透电流的传感器,用以记录实际海洋大气中氢渗透电流,并根据氢离子渗透量与腐蚀失重之间的线性关系对海洋大气中钢材的腐蚀速率进行预测.结果表明,实际海洋大气中,氢渗透电流与环境湿度存在着对应关系,环境湿度由大变小时,氢渗透电流由小变大.环境湿度交替变化,在试样表面完成干湿循环,促进了氢的渗透,实际海洋大气与摸拟海洋大气失重取得了较好的一致性.可以用氢渗透电流传感器实时监测海洋用钢在大气中的氢渗透情况及腐蚀失重情况.     

Nitriding of titanium by NH3 RF plasma: a study of the corrosion resistance and the mechanical properties of the protective films formed at the solid surface

The exposure of a titanium sample to an NH₃ low pressure plasma leads to the formation of a nitriding layer. The products formed at the titanium surface were identified by XRD spectroscopy. The modification of the corrosion resistance characteristics of titanium due to the NH₃ plasma treatment were investigated by electrochemical tests. The recorded polarization curves of the treated titanium samples were used to determine the values of the corrosion potential E_corr. This study confirms the increasing of the corrosion resistance as a function of the time exposure and the injected electric power in the silica reactor. The plasma treatment also induces drastic changes of the titanium target in hardness.