土壤中残余尿素对Q235钢微生物腐蚀的影响

利用电化学阻抗谱、动电位扫描测试技术、扫描电镜以及表面能谱分析方法在湿度为10%的土壤中,研究了尿素(0.05 mass%)对Q235钢微生物腐蚀的影响。结果表明,在接菌土壤中尿素对Q235钢腐蚀起加速作用,在灭菌土壤中尿素对Q235钢腐蚀起抑制作用。在接菌土壤中,试验前期阻抗谱上出现一个时间常数;5 d后变为两个时间常数,试件表面已生成一层腐蚀产物。试验后期出现Warburg阻抗,表明此时电极反应受扩散控制,并且接菌土壤中试样的腐蚀产物中存在S元素。     

海洋硫酸盐还原菌对X100钢腐蚀行为的影响

通过测定海水溶液中硫酸盐还原菌(SRB)生长曲线、溶液状态参数、自腐蚀电位、电化学阻抗谱和极化曲线的变化规律,研究了SRB的存在对X100钢在该体系中的腐蚀行为的影响。结果表明:SRB在海水培养基中的一个生长周期可分为快速生长阶段、稳定阶段和衰亡阶段。溶液S2-浓度和氧化还原电位与SRB数目密切相关,X100钢的自腐蚀电位随时间增加呈现先负移、然后正移、最后负移的变化规律;EIS结果表明,在接菌海水中,X100钢的腐蚀速率随着浸泡时间的增加呈现先增大、后减小、再增大的变化趋势;与灭菌海水中的腐蚀相比,X100钢在接菌海水中的腐蚀电流密度降低,腐蚀减弱,其原因是SRB生物膜的存在阻碍了海水与试样表面的直接接触,从而抑制了金属的腐蚀。     

海洋硫酸盐还原菌对Q235钢腐蚀行为的影响

采用失重法、开路电位、电化学阻抗谱(EIS)、极化曲线等方法,通过在海洋环境中浸泡不同时间对比分析有无硫酸盐还原菌(SRB)条件下Q235钢的腐蚀电化学特征,研究SRB对Q235钢的腐蚀行为的影响。结果表明,在含SRB的海水中,随着浸泡时间延长,Q235钢的腐蚀电流密度先从7.49mA·cm~(-2)增加至9.77mA·cm~(-2),然后逐渐减小至5.01mA·cm~(-2),最终增加至12.6mA·cm~(-2),且始终小于相同时间下无SRB海水中的腐蚀电流密度,表明SRB的存在抑制了Q235的腐蚀。在含SRB的海水中,Q235钢的腐蚀行为主要由Cl~-和生物膜共同影响。在SRB稳定生长阶段,腐蚀以生物膜抑制为主;在SRB指数生长阶段和衰亡阶段,生物膜抑制作用较弱,以Cl~-促进金属腐蚀为主。     

Surface characterization and corrosion behavior of 70/30 Cu-Ni alloy in pristine and sulfide-containing simulated seawater

The corrosion behavior of the 70/30 Cu-Ni alloy in stagnant, aerated pristine and sulfide-containing simulated seawater as a function of exposure time was investigated with polarization curve measurement and electrochemical impedance spectroscopy (EIS). It was demonstrated that the compact protective oxide film formed on the 70/30 Cu-Ni alloy resulted in the decrease of corrosion rate in aerated pristine seawater; while the corrosion rate of 70/30 Cu-Ni alloy in aerated sulfide-containing seawater increased dramatically due to the catalysis of the sulfide ions or sulfide scale for both the cathodic and anodic reactions. The impedance spectra and the corresponding equivalent circuits confirmed that a duplex layer of a surface film was formed on the 70/30 Cu-Ni alloy in aerated pristine seawater after a period of time and that the inner layer was responsible for the good resistance of the alloy; while only a porous and non-protective corrosion product layer formed on the 70/30 Cu-Ni alloy in aerated sulfide-containing seawater, which made small values of charge transfer resistance (R_ct) to last for a abnormally long time by interfering with the growth of the protective oxide film. The composition of the surface film on the alloy in pristine and sulfide-containing seawater for different exposure times were investigated thoroughly by XPS. It was found that the duplex corrosion product layer formed on the alloy in pristine seawater was composed of an inner Cu₂O and an outer CuO layer. The porous and non-protective corrosion product layer formed on the alloy in aerated sulfide-containing seawater was a mixture of CuCl, Cu₂S, NiS, Cu₂O and NiO with trace amounts of CuO and Ni(OH)₂ and that the most significant component was Cu₂S. In addition, SEM was used to analyze the topography of the 70/30 Cu-Ni alloy in both solutions after different exposure times.     

电化学方法研究锈层覆盖下碳钢的腐蚀规律

分别采用失重法与电化学方法(包括极化曲线、线性极化法和电化学阻抗技术)研究了碳钢在海水中浸泡48周的腐蚀规律。结果发现,短期浸泡在海水中的碳钢,表面生成的腐蚀产物薄且疏松,长期浸泡后,锈层逐渐分为两层:外锈层薄且疏松,内锈层厚且致密。短期浸泡,失重法与电化学方法得到的腐蚀规律一致,腐蚀速度逐渐减小并且数值相近,此时电化学方法可以用来准确的估算碳钢的腐蚀速度。长期浸泡,电化学方法测定的腐蚀速度转为逐渐增大,偏离了失重结果,并且锈层越厚偏差越大,此时电化学方法会过高估算腐蚀速度。     

Comparative study of the behaviour of AISI 304 SS in a natural seawater hopper, in sterile media and with SRB using electrochemical techniques and SEM

A comparative study of the electrochemical behaviour of stainless steel AISI 304 plates immersed in a natural seawater hopper and, under lab conditions, in sterile natural seawater, were carried out over seven weeks. The behaviour of these plates was, likewise, studied in seawater plus sulphate reducing bacteria (SRB) isolated from the natural seawater medium at the end of the seven week period. Electrochemical studies which measured the voltage over open circuit conditions (E_corr), linear polarisation and electrochemical impedance spectroscopy (EIS) were also carried out. The results have allowed us to profile the varying behaviour of the plates’ rusting in the natural seawater hopper, where a complex bio-film characteristic of natural environments is formed, as opposed to the processes of spreading in zones of high frequency due to the presence of voltage carrier species produced as the result of the transformation of sulphates into sulphides and to the lab conditions where a passive layer is formed, with capacitating behaviour, in the absence of bacteria, and a bio-film with sulphide inclusions is formed in the presence of the sulphate reducing bacteria (SRB) in an inductive semi-circle. The least protective passive layer appears in the presence of the SRB since the iron sulphide increases the susceptibility of steel to corrosion.     

Specification of sulfate reducing bacteria biofilms accumulation effects on corrosion initiation

The accumulation process of sulfate reducing bacteria (SRB) biofilms established in anaerobic stagnant batch bioreactors on the surface of carbon steel and the nutrient transport and corrosion products distribution in it were characterized by X‐ray Photoelectron Spectroscopy (XPS). In addition, the corrosion occurrence and development of carbon steel under SRB biofilm was investigated by Electrochemical Impedance Spectroscopy (EIS) in‐situ. The results show that the thickness of SRB biofilms increases exponentially with time in the beginning and after 14 days reaches a maximum. From then on, the accumulation rate decreases to zero. In mature biofilms, SRB dispersed throughout the biofilm. In the inner layer near the substrate, due to the high sulfate‐reducing activity of SRB, corrosion products such S^2?, H₂S and organic acid are present, which lead to corrosion occurrence and development. In the outer layer of the biofilm SRB can also reduce the SO^2?₄ to SO^2?₃ and S₂O^2?₃. This metabolism process enhances the Fe²⁺ transfer from the inner to the outer side. The activity of SRB in the biofilm plays a key role in the initial corrosion process.     

Corrosion behavior of coating with plasma sprayed 8YSZ on the surface of carbon steel

The corrosion behavior of plasma sprayed 8YSZ(ZrO2 stabilized by 8 wt.%Y2O3)coating on the surface of carbon steel in seawater was investigated.The electrochemical impedance spectroscopy was used as a non-destructive evaluation technique to monitor the protection properties of the coating when it was immersed in seawater,and corrosion products were characterized by scanning electron microscopy,energy dispersive spectrometry and X-ray photoelectron spectroscopy.The results indicated that three time constants were obtained during the initial immersion period,and then a new time constant appeared due to the formation of rust layer,which was corresponding to the corrosion process.Corrosion products were formed on the coating surface as well as inside the coating,and the crystalline composition of the rust layer mainly consisted of γ-FeOOH.     

SRB 对 X70 钢在土壤模拟溶液中腐蚀行为的影响

采用失重法、SEM、EDS微观分析方法和电化学阻抗技术研究了X70钢在有/无SRB的侵蚀性土壤模拟溶液中的腐蚀行为。结果表明,在无菌介质中,X70钢表面生成不具有保护性的腐蚀产物,其腐蚀速率随浸泡时间的延长而增大;在有菌介质中,钢表面形成致密的生物膜,对界面传质有一定的阻碍作用,从而减轻X70钢的腐蚀。腐蚀产物的吸附及S含量随浸泡时间的延长而增加,使得腐蚀产物膜疏松易脱落,促进了基体的腐蚀。无菌介质中腐蚀产物内层的稳定性与腐蚀产物的沉积及分布有关;而在有菌介质中,多孔的胞外聚合物对活化过程中的质量传输过程有一定阻碍作用。     

Microbial Corrosion in Linepipe Steel Under the Influence of a Sulfate-Reducing Consortium Isolated from an Oil Field

This work investigates microbiologically influenced corrosion of API 5L X52 linepipe steel by a sulfate-reducing bacteria (SRB) consortium. The SRB consortium used in this study was cultivated from a sour oil well in Louisiana, USA. 16S rRNA gene sequence analysis indicated that the mixed bacterial consortium contained three phylotypes: members of Proteobacteria (Desulfomicrobium sp.), Firmicutes (Clostridium sp.), and Bacteroidetes (Anaerophaga sp.). The biofilm and the pits that developed with time were characterized using field emission scanning electron microscopy (FE-SEM). In addition, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and open circuit potential (OCP) were used to analyze the corrosion behavior. Through circuit modeling, EIS results were used to interpret the physicoelectric interactions between the electrode, biofilm and solution interfaces. The results confirmed that extensive localized corrosion activity of SRB is due to a formed biofilm in conjunction with a porous iron sulfide layer on the metal surface. X-ray diffraction (XRD) revealed semiconductive corrosion products predominantly composed of a mixture of siderite (FeCO₃), iron sulfide (Fe _x S _y ), and iron (III) oxide-hydroxide (FeOOH) constituents in the corrosion products for the system exposed to the SRB consortium.     

Zn-Al-Mg-RE涂层在含SRB海水中的耐腐蚀性与机理

利用高速电弧喷涂技术在Q235钢基体上制备Zn-Al-Mg-RE涂层,采用环氧改性有机硅树脂对涂层进行封孔,在含硫酸盐还原菌(SRB)海水中浸泡后,采用EIS,PC等方法研究Zn-Al-Mg-RE涂层在SRB一个生长周期内的腐蚀行为,并对涂层进行表面微观形貌和化学成分分析,探讨其腐蚀机理。结果表明:封孔和未封孔的Zn-Al-Mg-RE涂层在含SRB海水中的腐蚀速率均呈先增大后减小的趋势;封孔后Zn-Al-Mg-RE涂层的耐腐蚀性得到较大提高。经过浸泡后的Zn-Al-Mg-RE涂层表面覆盖了一层微生物和腐蚀产物组成的混合物层和钝化膜层,避免了涂层进一步遭受损坏。     

Effect of Sulfate Reduced Bacterium on Corrosion Behavior of 10CrMoAl Steel

 The effects of sulfate reduced bacterium (SRB) on the corrosion behavior of 10CrMoAl steel in seawater were studied by chemical immersion, potentiodynamic polarization, electrochemical impedance spectroscopy measurement, and scanning electron microscope techniques. The results show that the content of element sulfur in the corrosion product of 10CrMoAl steel in seawater with SRB is up to 923%, which is higher than that of the same in sterile seawater. X ray diffraction demonstrates that the main corrosion product is FeS. SRB increases the corrosion rate by anodic depolarization of the metabolized sulfide product. SEM observation indicates that the corrosion product is not distributed continuously; in addition, bacilliform sulfate reduced bacterium accumulates on the local surface of 10CrMoAl steel. Hence, SRB enhances sensitivity to the localized corrosion of 10CrMoAl steel in seawater.     

23Co14Ni12Cr3Mo超高强钢在模拟海水环境中的腐蚀行为

采用模拟海水干湿交替气氛的周期浸润腐蚀、模拟海水大气环境的中性盐雾腐蚀及模拟海水全浸区的全浸腐蚀三种加速腐蚀实验方法以及电化学阻抗谱技术进行了23Co14Ni12Cr3Mo超高强钢在海水模拟环境下的腐蚀行为。采用扫描电镜和X射线衍射方法对腐蚀形貌及腐蚀产物组分进行分析研究。结果表明:在模拟环境加速腐蚀实验中,23Co14Ni12Cr3Mo超高强钢腐蚀产物可分为外层锈层γ-FeOOH和内层锈层α-FeOOH,通过模拟三种海水环境的腐蚀速率得出干湿交替环境中的耐腐蚀性最差,腐蚀均是从点蚀开始,慢慢扩大,由局部腐蚀逐渐发展成均匀腐蚀。     

Effect of Sulfate-reducing Bacteria on Corrosion Behavior of Mild Steel in Sea Mud

Microbiologically influenced corrosion （MIC） is very severe corrosion for constructions buried under sea mud environment. Therefore it is of great importance to carry out the investigation of the corrosion behavior of marine steel in sea mud. In this paper, the effect of sulfate-reducing bacteria （SRB） on corrosion behavior of mild steel in sea mud was studied by weight loss, dual-compartment cell, electronic probe microanalysis （EPMA）, transmission electron microscopy （TEM） combined with energy dispersive X-ray analysis （EDX） and electrochemical impedance spectroscopy （EIS）. The results showed that corrosion rate and galvanic current were influenced by the metabolic activity of SRB. In the environment of sea mud containing SRB, the original corrosion products, ferric （oxyhydr） oxide, transformed to iron sulfide. With the excess of the dissolved H2S, the composition of the protective layer formed of FeS transformed to FeS2 or other non-stoichiometric polysulphide, which changed the state of the former layer and accelerated the corrosion process.     

炼油厂冷却水系统硫酸盐还原菌对316L不锈钢点腐蚀的研究

用开路电位、动电位扫描、电化学阻抗技术和扫描电镜等方法,研究了316L不锈钢在硫酸盐还原菌(SRB)溶液中的腐蚀电化学行为,分析了炼油厂冷却水系统微生物腐蚀的特征及机制.结果表明,在含有SRB溶液中的自腐蚀电位(Ecorr)和点蚀电位(Epit)随浸泡时间的增加而负移,极化电阻(Rp)随浸泡时间的增加而减小;在含有SRB溶液中的腐蚀速率均大于在无菌溶液中;SRB的生长代谢活动影响了316L SS表面的腐蚀过程,使不锈钢表面的钝化膜层腐蚀破坏程度增加,加速了316L SS的腐蚀.     

硫酸盐还原菌的生长过程及其对D36钢海水腐蚀行为的影响

通过测定海水中硫酸盐还原菌(SRB)的生长曲线及其不同生长阶段的硫离子浓度、D36钢电极体系的氧化还原电位、自腐蚀电位、极化曲线和电化学阻抗谱,研究了硫酸盐还原菌对该体系钢电极腐蚀行为的影响。结果表明,海水中D36钢氧化还原电位和自腐蚀电位主要由体系中硫酸盐还原菌代谢产物硫离子的浓度所决定;体系的阳极和阴极反应速率均在硫酸盐还原菌增殖期增加,而且阳极反应速率衰亡期和残余期保持不变。     

Microbiologically influenced corrosion of X60 carbon steel in CO2‐saturated oilfield flooding water

The corrosion behavior of X60 carbon steel in CO₂‐saturated oilfield flooding water inoculated with sulfate‐reducing bacteria (SRB) was investigated using polarization curves and electrochemical impedance spectroscopy (EIS). With the propagation of SRB in the flooding water, the pH values of flooding water increased quickly in the initial 2 days and remained relatively steady during the later stage. Polarization curves showed that the corrosion current density decreased during the first 10 days due to the protection of corrosion products and SRB‐biofilms, and then increased possibly due to the partial detachment of the corrosion products and the biofilms. EIS analysis also showed that the charge transfer resistance increased initially and then decreased with exposure time. In the beginning of corrosion, the anodic dissolution of X60 steel was dominated by CO₂. After the formation of SRB‐biofilms, part of FeCO₃ corrosion products was converted to incompact FeS precipitates by SRB bio‐mineralization. Thus, the dispersed iron sulfide in SRB‐biofilms and X60 steel base may constitute a galvanic couple, accelerating the localized corrosion of the steel base in the flooding water.     

Effect of Co and W on the corrosion behaviour of 1% Cr steel in flowing synthetic seawater

The aqueous corrosion characteristics of 1% Cr‐steel alloyed with small amounts of Co and W in synthetic seawater was studied by using immersion weight‐loss tests, electrochemical corrosion tests (potentiodynamic tests and electrochemical impedance spectroscopy (EIS) measurements) and analytical techniques. 1% Cr steels containing Co or W from 0.2 to 0.4 wt.% showed higher corrosion resistance than the 1% Cr steel in the immersion and potentiodynamic tests. EIS measurements showed that the Nyquist plot presented one time constant. Furthermore, the Co‐ and W‐bearing steels present higher R_p values than the 1% Cr steel through all the test period. The better corrosion resistance of the Co‐and W‐bearing steels is attributed to the protectiveness of the surface layer. The corrosion products were examined using electron probe microanalysis (EPMA) and X‐ray photoelectron spectroscopy (XPS). The results of EPMA indicated that Cr was concentrated in the inner region of the rust layer, while Co and W were distributed all over the rust layer. XPS results showed that Co existed as a trivalent oxide in the rust layer and W in the rust appeared in the form of a WO₄ compound. These compounds act as a factor for corrosion resistance in aqueous solutions.     

生物膜对碳钢腐蚀的影响

由江汉油由田采油厂污水中分离,提纯出来的硫酸盐还原菌菌株,采用ＡＰＩＲＰ－３８推荐使用的培养基生成生物膜,利用交流阻抗技术研究了生物膜与腐蚀之间的关系。细胞新陈代谢产物及腐蚀产生的分析借助于电子探针及气相色谱／质谱联用技术。     

硫酸盐还原菌对CaCO3垢层下20号钢腐蚀的影响

采用室内模拟实验的方法,研究了硫酸盐还原菌（SRB）和CaCO₃垢层共存对20号钢腐蚀行为的影响。通过腐蚀失重法研究平均腐蚀速率,通过电化学阻抗谱（EIS）和开路电位（OCP）研究注入水溶液中20号钢腐蚀电化学行为,利用扫描电镜（SEM）、EDS和Raman光谱分析20号钢表面腐蚀产物的形貌和成分,采用激光共聚焦显微镜（CLSM）分析20号钢的点蚀坑深度。结果表明,SRB与CaCO₃垢层存在协同作用,CaCO₃垢层的孔隙率和垢层下的厌氧环境为SRB的黏附和生长提供了便利的条件,接种SRB对CaCO₃垢层下20号钢的均匀腐蚀和局部腐蚀均有促进作用。