模拟生物膜方法研究钢在海水中的腐蚀行为

近年来,微生物腐蚀受到广泛重视。本文根据生物膜的结构特征,以含羧酸官能团的β－Ｄ甘露糖醛酸单元等构成的天然高分子多糖凝胶沉积于电极表面,形成模拟生物膜,初步建立起模拟生物膜环境的实验方法,并探讨了模拟海水ＮａＣｌ溶液中生物膜对１０ＣｒＭｏＡｌ、Ｅ２低合金钢和１８－８不锈钢腐蚀行为的影响。采用极化曲线法、电偶电流测试及交流阴抗谱等电化学方法研究了上述材料在模拟生物膜环境中的腐蚀电化学行为,得到了一些     

海洋微生物对316不锈钢的电化学腐蚀行为

采用自腐蚀电位、电化学极化曲线、电化学阻抗谱技术研究了316不锈钢在无菌培养基介质和海水微生物接种培养有菌培养基介质中不同周期的腐蚀行为．结果表明,316不锈钢电极在有菌介质中比在无菌介质中的腐蚀电流密度大,腐蚀电位负移,微生物加速了不锈钢的腐蚀速度．随着浸泡时间的增加,有菌介质中的不锈钢电极极化电阻值逐渐减小,表明了海洋微生物的附着和繁殖加速了316不锈钢的腐蚀速率,降低了其在海洋环境中的耐蚀性．     

氧化亚铁硫杆菌作用下A3钢的腐蚀行为

采用微生物学方法、电化学方法和表面分析技术研究了A3钢在氧化亚铁硫杆菌中的腐蚀特征和生物膜形貌, 分析了微生物的存在对A3钢电化学行为的影响. 极化曲线测试结果表明, 细菌的存在使浸泡20天后A3钢电极的自腐蚀电位升高, 腐蚀电流密度增大. 原子力显微镜测试结果表明, 浸泡7天的A3钢表面生物膜分布不均匀, 从而引发点蚀萌生. 由于细菌的代谢作用以及A3钢表面腐蚀产物与生物膜的特殊形貌特征, 浸泡在菌液中7天后的A3钢表面有点蚀出现; 随着时间的延长, A3钢表面的点蚀坑深度增大且数量增多, 氧化亚铁硫杆菌的存在使A3钢的局部腐蚀程度加剧.     

生物膜和腐蚀产物膜对A3钢的腐蚀作用研究

应用电化学方法和表面分析技术(AFM和SEM)研究硫酸盐还原菌(SRBB)(生物环境)及其腐蚀产物(非生物环境)对A3钢腐蚀行为的影响以及A3钢在两种不同环境下的腐蚀特征.结果表明:于不同时期生成的微生物膜和腐蚀产物膜,对材料的腐蚀起着不同的作用.生成的生物膜越厚越容易剥落,而不均匀的微生物膜将引起材料的局部腐蚀.在非生物环境中生成的腐蚀产物膜比在生物环境中生成的膜更加紧密地黏附于金属的表面.     

碳钢在微生物介质中的腐蚀电化学行为

硫酸盐还原菌（SRB）生长代谢，溶液pH值从7．5下降到5．8，并在碳钢表面形成生物膜，改变了生物膜下碳钢表面的微环境，促进碳钢点蚀的形成，清除表面的腐蚀产物后，碳钢基体表面为分布不均匀的溃斑，发生严重的点蚀行为，而RB的活性和生物膜的结构诱发碳钢腐蚀的形成和生长，在微生物快速生长过程中出现明显的氢扩散电流峰，加剧碳钢的渗氢行为，采用电化学阻抗（EIS）研究了碳钢在微生物腐蚀过程中生物膜的结构与腐蚀相应的变化关系。     

A3钢在芽孢杆菌作用下的腐蚀行为

采用表面分析技术、失重法和电化学测试技术研究了A3钢在芽孢杆菌(Bacillus)作用下的腐蚀行为.扫描电子显微镜(SEM)分析结果表明,浸泡7d时,芽孢杆菌会在A3钢表面形成致密的生物膜,有效阻隔了溶液对基体的腐蚀,抑制了腐蚀过程.电化学交流阻抗测试结果显示,含菌体系中的试样表面经历了2个时间常数→3个时间常数→2个时间常数的变化过程.失重法和极化曲线测试结果表明,芽孢杆菌的细菌活性对生物膜的保护作用有着决定性的影响,当微生物活性下降,生物膜的保护能力也会大幅降低.     

自然水体中生物膜的主要化学组分与水体中相关化学物质的关系

自然水体中大多数微生物是以附着状态而不是以游离状态存在的 [1] .微生物附着在固体表面形成生物膜 ,存在于河流、湖泊及湿地环境中的岩石、表层沉积物和悬浮颗粒物表面 ,由不同种类的微生物组成 [2 ] .从环境微生物学角度来看 ,生物膜被定义为一种活跃地生长发育着的单一或混合的微生物群体 ,其不可逆地附着到一种活跃的或非活跃的表面 [3] ,并由微生物群体组成 [4 ] .从环境化学角度来看 ,生物膜是由金属氧化物、有机质及少量矿物质组成的 .金属氧化物和有机质在影响重金属于固相吸附的相对作用已有报道 [5～ 10 ] .生物膜在自然水体中是…     

5083铝合金在海水中的腐蚀电化学行为及活性氯影响研究

采用动电位极化、循环极化和全浸腐蚀试验方法,研究了5083铝合金在静止海水中的腐蚀电化学性能以及活性氯的影响.结果表明,在本文设置的防污活性氯浓度范围(0.2～0.5mg/L)内,活性氯对铝合金的阴极和阳极电化学极化以及腐蚀行为没有明显影响,并可提高铝合金的耐点蚀能力,海水的pH值对铝合金的腐蚀具有显著的影响.该研究为海水中5083铝合金的防腐防污提供了依据.     

渗铝钢在海水中的电化学行为研究

应用化学浸泡实验,电化学测试技术研究渗铝钢在海水中的电化学行为.试验表明,在海水中渗铝钢的腐蚀电位比20#钢的负,其阳极活性大于后者,在低电位下发生阳极溶解.20#钢和渗铝钢的腐蚀速率分别为5.80mg/dm2·d和3.36mg/dm2·d.渗铝钢在海水中具有优良的耐蚀性能是由于环境遮断和电偶保护的综合效果.其腐蚀产物含有氯离子,说明氯离子参与海水中的腐蚀过程,是导致腐蚀的主要原因.渗铝钢除了表层形成的Al、Fe化合物和致密、连续、具有高效防护作用Al的氧化物保护膜外,Al Fe合金层起到牺牲阳极的电化学保护作用.     

不同形状TiO2纳米材料在耐NaCl溶液及微生物腐蚀中的应用

采用电沉积方法研究制备了分别含TiO2纳米球、TiO2纳米线和TiO2纳米管的一系列Ni-P-Cr基复合镀层的耐海水微生物腐蚀的新型复合材料.TiO2纳米材料的形貌采用TEM表征.以SEM、EDX测试技术研究了复合镀层的表面形貌和元素组成.并分别在质量分数为3.5%NaCl溶液及以硫酸盐还原菌(SRB)为腐蚀介质,应用极化曲线和电化学阻抗谱法(EIS)研究了各种复合镀层的耐蚀和抗菌性能.结果表明,含TiO2纳米管的Ni-P-Cr基复合镀层具有更优良的耐电解质及微生物腐蚀性能.     

Accelerated anaerobic corrosion of electroactive sulfate-reducing bacteria by electrochemical impedance spectroscopy and chronoamperometry

Many microbial species can use cathodes as electron donors for metabolism. This direct electron transfer (DET) pathway has rarely been proposed in biocorrosion processes. DET from Q235 carbon steel to the sulfate-reducing bacteria (SRB) Desulfovibrio caledoniensis and its effect on the corrosion behavior of carbon steel were investigated in the present study. Electroactive SRB biofilm was found to play a key role in the ennoblement of the corrosion potential (E_corr) and in the acceleration of the corrosion rate, indicating that SRB mainly affected the cathodic reaction of low carbon steel corrosion. In addition, SRB biofilm obtained electrons from carbon steel electrode polarized at − 0.74 V. These findings present new evidence for DET between SRB biofilm and carbon steels.     

稀土对铬锰氮不锈钢在稀硫酸介质中腐蚀磨损性能的影响

研究了稀土对铬锰氮不锈钢的腐蚀性能及腐蚀磨损性能的影响，稀土使各锰氮不锈钢的腐蚀电位正移、维钝电流降低、热力学稳定性提高，故其耐蚀性提高，抗磨性改善，铬锰氮不钢的最佳稀土含量为０．０２－０．０６％，为生产提供了必要的工艺参数。     

pH/Cl-复合探针技术对钢筋混凝土电化学除氯的原位检测

采用恒电流法电化学除氯处理受氯离子污染的钢筋混凝土试样,并用pH/Cl^-复合探针原位检测电化学除氯过程钢筋混凝土不同位置孔隙液的氯离子含量与pH值分布,同时用线性极化曲线和交流阻抗谱图等电化学技术考察钢筋的腐蚀性能,探讨电化学除氯过程的混凝土微环境和钢筋腐蚀速率. 研究结果表明：在电化学除氯过程,混凝土孔隙液的氯离子浓度逐降,而pH值在初期略有升高,随之其pH值略降;电化学除氯施加的阴极电流,使钢筋处于阴极极化状态而得到保护;除氯停止（即退极化）后钢筋的腐蚀电位明显正移,腐蚀电流降低,极化电阻升高,表明电化学除氯能改善钢筋的腐蚀环境,降低钢筋的腐蚀速率.     

碳钢在生物膜和硫化物膜下的电化学腐蚀行为

应用丝束电极技术比较了SRB生物膜以及硫化物膜对Q2 35碳钢腐蚀过程的影响机制 ,采用电位、电流扫描技术测试了生物膜和FeS膜下的碳钢腐蚀不均匀性特征 ,发现由于膜的导电性致使表面电位扫描已不能作为膜下局部腐蚀的判据 .动电位扫描表明无氧近中性溶液中 ,硫化物膜对碳钢具有一定保护作用 .电化学阻抗谱显示 ,硫化物膜电容增加缓慢 ,其极化电阻Rp 随时间呈先增后降的趋势 .与硫化物膜相比 ,生物膜表现出极大的电容 (10 4 ～ 10 5μF/cm2 ) ,且膜电容随时间呈S型增加 ,而极化电阻Rp 则呈指数下降 ,由此可知生物膜加速了腐蚀     

Effect of biofilm on naval steel corrosion in natural seawater

The behaviour of steel in natural environments is not only dependent on material properties and environmental aggressiveness, but also on micro-organisms which can exist within it. The electrochemical evolution of the interface formed on BV-grade A naval steel exposed to natural seawater in the presence and absence of marine micro-organisms has been studied over 30?days. The results obtained by electrochemical techniques including linear polarisation and electrochemical impedance spectroscopy revealed that a heterogeneous layer formed by a mixture of corrosion products and biofilm grew on the material surface in natural seawater, producing an increase of the corrosion rate and then a decrease in the corrosion resistance under diffusion process. In this case, the protective layer formed by the corrosion products can be subject to the localised breakdown. In sterile seawater, the formation of two layers at the metal surface generated by organic and/or inorganic compounds deposits (outer layer) and corrosion products (inner layer) is concluded. Using our experimental data, electrical models are proposed. They describe the impedance distribution for carbon steel exposed to both environments. Scanning electron microscopy, energy dispersive X-ray spectrometry analysis and optic microscope reproductions were obtained. They allowed an interpretation of the effect of the marine biofilm on the behaviour of the carbon steel in seawater.     

Corrosion inhibition of 302 stainless steel with schiff base compounds

The effects of 2,2′-[bis-N(4-cholorobenzaldimin)]-1,1′-dithio (BCBD) and bis-(2-aminophenyl) disulphide (BAPD) on the corrosion behavior of 302 stainless steel in 0.5 M sulfuric acid solution as corrosive medium were investigated using weight loss and potentiostatic polarization techniques. Some corrosion parameters such as anodic and cathodic Tafel slopes, corrosion potential, corrosion current density, surface coverage degrees and inhibition efficiencies were calculated. The polarization measurements indicated that the inhibitors were of mixed type which inhibited corrosion by parallel adsorption on the surface of stainless steel due to the presence of more than one active centre in the inhibitor molecule. The adsorption followed Langmuir adsorption isotherm. The activation energy and thermodynamic parameters were calculated at different temperatures. Results showed that BCBD had a higher inhibition efficiency compared with BAPD.     

Microbiologically influenced corrosion of 304 stainless steel by aerobic Pseudomonas NCIMB 2021 bacteria: AFM and XPS study

Microbiologically influenced corrosion (MIC) of stainless steel 304 by a marine aerobic Pseudomonas bacterium in a seawater-based medium was investigated by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM was used to observe in situ the proliferation of a sessile Pseudomonas cell by binary fission. The development of a biofilm on the coupon surface and the extent of corrosion damage beneath the biofilm after various exposure times were also characterized by AFM. Results showed that the biofilm formed on the coupon surface increased in thickness and heterogeneity with time, and thus resulting in the occurrence of extensive micro-pitting corrosion; whilst the depth of pits increased linearly with time. The XPS results confirmed that the colonization of Pseudomonas bacteria on the coupon surface induced subtle changes in the alloy elemental composition in the outermost layer of surface films. The most significant feature resulting from microbial colonization on the coupon surface was the depletion of iron (Fe) and the enrichment of chromium (Cr) content as compared to a control coupon exposed to the sterile medium, and the enrichment of Cr increased with time. These compositional changes in the main alloying elements may be correlated with the occurrence of extensive micropitting corrosion on the surface.     

Corrosion of underground pipelines in clay soil with varied soil layer thicknesses and aerations

Underground pipelines suffer from corrosion in the soil. In this work, weight-loss testing, electrochemical measurements and surface analysis techniques were used to investigate the pipeline steel corrosion in a Regina clay soil with varied soil layer thicknesses and gassing conditions (i.e., aerobic, CO₂-containing and anaerobic). Results demonstrate that the steel corrosion is dependent on the soil layer thickness, where a maximum corrosion rate is recorded under the 5 mm thick soil due to the competitive impact of the blocking effect of the soil layer and its moisture-retaining ability on the corrosion. In thin soil layers, the corrosion is accelerated with the increasing soil thickness due to more water contained in the soil. With the further increase of the soil layer thickness, the blocking effect of the soil on diffusion of corrosive species is dominant. The corrosion of the steel also depends heavily on the gassing condition in the soil. Under the specific soil layer thickness, the steel suffers from the highest corrosion rate in aerobic soil, which is followed by the 5% CO₂/N₂-containing soil. The steel corrosion is negligible (0.006 mm/y only) when the soil is purged with N₂. In addition to uniform corrosion, localized corrosion occurs on the steel under soil due to its heterogeneous nature at a much greater rate than the uniform corrosion. The maximum localized corrosion rates in 5% CO₂/N₂-containing 5 mm thick soil layer and in the 3 mm thick soil that is open to air are 1.03 mm/y and 0.72 mm/y, respectively. As a comparison, the uniform corrosion rates are 0.05 mm/y and 0.04 mm/y under the two conditions.     

Evaluation of crude methanolic mangrove leaves extract for antibiofilm efficacy against biofilm-forming bacteria on a cooling tower wastewater system

The present study demonstrated microbial corrosion protection of MS 1010 on cooling tower water using plant-based inhibitors derived from methanolic extraction of dry mangrove leaves (R.mangle and A.marina), and its assessment of antibacterial activity against corrosive bacteria (B.megaterium) was investigated. FT-IR and GC–MS analyzed the inhibitors component and corrosion behavior of MS 1010 on cooling water, with and without inhibitors were analyzed by EIS and Tafel studies. GC–MS spectra confirmed the presence of Myo-Inositol, 4-C-methyl and chromene as major constituents presented on the R.mangle whereas Lupeol, trifluoroacetate and beta-amyrin compounds were found on the A.marina. In the cooling water, these two inhibitors demonstrated outstanding antibacterial activity and controlled biofilm growth. As plant-based inhibitors were used in cooling water systems, EIS data showed a significant increase in R_ct value when compared to the control system. Tafel plot indicates inhibitors have mixed inhibitory effects and for the systems with and without inhibitors, the i_corr value was 1.5649A and 2.0875A, respectively. At the optimal dose of 25 ppm, the inhibitory efficiency of MERM and MEAM was 81% and 80%, respectively. The overall discussion reveals that inhibitor substances can be absorbed on the metal surface and then act as a dual role in inhibiting corrosive bacterial growth and barrier to the corrosion process in the cooling water system.