SRB对X70管线钢在近中性pH溶液中腐蚀行为的影响

采用电化学阻抗、动电位极化及微观观察法,对比了有、无硫酸盐还原菌(SRB)的情况下X70管线钢在近中性p H溶液(NS4)中的腐蚀行为,研究了SRB生长周期对X70钢腐蚀行为的影响。结果表明:X70钢在无菌溶液中腐蚀速率随时间增加呈单一增大的趋势。SRB在NS4溶液中的生长周期分为对数繁殖期(1~3 d),稳定生长期(4~7 d)和衰亡期(7~14 d)3个阶段。SRB对X70钢在NS4溶液中腐蚀速率的影响与其在溶液中生长规律有关:当SRB处于对数繁殖期和稳定期时,X70钢表面覆盖一层致密的生物膜,对钢起到了保护作用,此时X70钢的腐蚀速率比无菌条件下低;当SRB进入衰亡期,X70钢腐蚀的程度比无菌介质中严重,钢表面腐蚀产物逐渐增多,生物膜出现破裂,腐蚀速率增大。     

动态直流干扰和SRB共同作用下X80钢的腐蚀行为

目的 探究电气化铁路动态直流干扰和硫酸盐还原菌(SRB)及其协同作用对X80钢腐蚀行为的影响。方法 通过构建动态杂散电流室内模拟试验装置,对浸泡在灭菌和接菌(SRB)NS4溶液中的X80钢施加周期性阴极保护和方形脉冲动态杂散电流干扰。采用MPN计数法和活/死细胞染色方法分析了X80钢表面SRB的数量和活性,通过SEM、EDS、XPS和CLSM等表面分析技术,结合失重测试对灭菌和接菌环境下X80钢的腐蚀产物、腐蚀速率及腐蚀后形貌进行了表征。结果 动态直流干扰对溶液中SRB的生长未产生明显影响,但对SRB及生物膜在试样表面的附着产生较大影响。阴极保护会抑制SRB在X80钢表面的附着,通过抑制SRB的呼吸作用降低金属表面SRB活性,从而降低X80钢的微生物腐蚀。阳极干扰电流促进SRB在X80钢表面的附着,金属表面生物膜内的SRB活性增强。X80钢在灭菌环境下–400、0、500 mV试样的腐蚀速率分别为0.086 35、0.219 2、0.458 3 mm/a,分别为自然腐蚀速率的0.97、2.46、5.15倍。接菌环境下X80钢的腐蚀速率反而下降,但X80钢表面的最大点蚀坑深度明显增大。结论 在动态直流干扰下,X80钢的腐蚀速率大幅增加,单次短时直流干扰的累积对X80钢产生了十分严重的破坏。同时动态直流干扰通过促进X80钢表面SRB的活性,从而加速其微生物腐蚀,SRB生物膜在一定程度上减缓了X80钢的动态直流干扰腐蚀,但其与动态直流干扰共同作用加剧了X80钢表面的点蚀。     

流体冲刷作用对SRB的腐蚀行为影响研究

采用数值仿真与实验相结合研究了流体冲刷下SRB的腐蚀行为。基于计算流体动力学(CFD)得到的管道腐蚀区域预测云图和粒子运动轨迹图结果，预判管道腐蚀部位，结果表明管道底部较顶部腐蚀、管道出口处腐蚀较入口处严重；在预判管道腐蚀部位布置研究电极，运用电化学方法以及表面分析方法探究了流体冲刷下SRB的腐蚀规律。结果表明，SRB在金属表面未形成生物膜时(未进行预膜处理)，冲刷腐蚀占主导地位，金属表面有明显的冲刷腐蚀特点，腐蚀产物主要以Fe的氧化物为主。当SRB在金属表面预先形成致密生物膜时(进行预膜处理)，SRB腐蚀占主导地位，生物膜会减缓冲刷腐蚀，但膜下SRB的生命活动会与金属基体发生电子交换，从而发生SRB腐蚀，腐蚀产物主要以硫铁化合物为主。     

温度与SRB协同作用下X70钢在海泥模拟溶液中应力腐蚀行为研究

研究了温度对硫酸盐还原菌(SRB)活性的影响,并采用慢应变速率拉伸实验研究了不同温度下X70钢在含SRB的海泥模拟溶液中应力腐蚀行为及其开裂机理。结果表明,SRB在海泥模拟溶液中生存温度范围为20～40℃,且随温度增加,SRB活性增加,数量增大。X70钢表面生物膜保护性与SRB活性和数量密切相关。20℃时,由于SRB数量最少,X70钢在含SRB海泥中应力腐蚀开裂(SCC)敏感性最小;30℃时,X70钢表面的生物膜与基体金属构成大阴极小阳极面积比的腐蚀原电池,耐蚀性最低,此时SCC机理为阳极溶解和氢致开裂共同作用下的混合断裂;40℃时SRB活性最好,X70钢表面形成较为完整生物膜,耐蚀性最好,但SCC敏感性最高,其开裂机理为氢致开裂。     

pH值对X70钢在海泥模拟溶液中微生物腐蚀行为的影响

采用动电位极化、电化学阻抗技术研究了不同pH值对X70钢在含硫酸盐还原菌(SRB)的南海海泥模拟溶液中电化学行为的影响,分析了X70钢表面发生的电化学反应。结果表明,溶液的pH值能影响SRB的生长,进而影响X70钢在南海海泥模拟溶液中的腐蚀行为。SRB在pH值为8条件下生长情况最好,在pH值为6条件下次之,在pH值为10条件下最差。pH值为8时,SRB生长期分为3个阶段:对数增长期、稳定生长期和衰亡期;pH值为6和10时,SRB生长期分为两个阶段:对数增长期和衰亡期。在对数增长期,SRB数量较少,微生物腐蚀作用较弱,X70钢的Ecorr较高,但当SRB数量增多后,微生物腐蚀作用增强,生物膜疏松且易脱落,导致局部腐蚀现象严重,Ecorr逐渐降低,金属腐蚀热力学倾向增大。在pH值为8条件下,微生物腐蚀作用最强,金属腐蚀速率最快;在pH值为10条件下,金属表面易形成钝化膜,且微生物腐蚀作用较弱,腐蚀速率最慢。     

2507双相不锈钢在含硫酸盐还原菌冷却水中的腐蚀

采用电化学测试、失重法、扫描电镜及能谱分析等方法研究了2507双相不锈钢在含体积比为0.5%、1%、2%硫酸盐还原菌(SRB)冷却水模拟溶液中浸泡30d后的腐蚀行为。结果表明:当浓度低于1%SRB时,钢表面生长缓慢,对于钢腐蚀影响相比于未添加SRB的基本没变化。而浓度达到2%SRB时,钢表面生长活动明显旺盛,对于钢的腐蚀倾向性显著增加,相比于不添加SRB的钢腐蚀速率增长了4倍多,钢表面多处生成斑状黑褐色腐蚀产物FeS。但2507双相不锈钢在含SRB冷却水中腐蚀程度均属于轻度腐蚀,且点蚀电位高达约1.2 V。     

X80管线钢表面SRB生物膜特征及腐蚀行为

采用SEM、Raman光谱、XPS等分析手段,结合扫描振动电极(SVET)、微区电化学测试和电化学阻抗谱(EIS)等电化学测量技术,研究含硫酸盐还原菌(SRB)的模拟海水中X80管线钢表面生物膜的形成、特征,生物膜与膜下金属的交互作用,以及管线钢腐蚀行为及电化学过程特征。结果表明:SRB微菌落及胞外聚合物(EPS)形成初期,EPS的屏障作用抑制X80钢的腐蚀过程;SRB生物膜形成后,X80钢的自然腐蚀电位降低约20 mV,SRB显著促进了管线钢的腐蚀过程;浸泡后期SRB及其生物膜使X80钢腐蚀速率较灭菌对照组高出约1个数量级。SRB生物膜与腐蚀产物Fe2+/Fe3+间存在络合、螯合作用,细胞及其代谢产物硫化物与金属间存在直接或间接电子交互作用,这些作用相互协同耦合,促使生物膜下局部腐蚀的发生和发展。     

硫酸盐还原菌对铜合金腐蚀电化学行为的影响

用电化学方法研究了硫酸盐还原菌（SRB）生物膜对HSn70-lAB和BFe30-1-1铜合金腐蚀的电化学行为；用扫描电镜（SEM）和透射电镜（TEM）及X-射线能谱（EDS）分析了铜合金表面生物膜特征及其成分。结果表明，铜合金表面生物腐蚀与SRB的生长特性密切相关，SRB处于指数生长期时，Hsn70-lAB和BFe30-1-1铜合金的自腐蚀电位（Ecarr）和极化电阻（彤均迅速下降，腐蚀加剧，且后者腐蚀速度大于前者；而当SRB进人稳定生长阶段，两种合金的Ecarr和Rp均缓慢下降，腐蚀速度减缓，且二者腐蚀速度接近。表面生物膜的特征也有较大区别，HSn70-lAB铜合金表面的腐蚀产物膜比较平滑，BFe30-1-1铜合金表面的腐蚀产物膜较粗糙；且后者表面膜中S含量高于前者，腐蚀倾向明显增强。     

应用原子力显微镜研究硫酸盐还原菌对A3钢的腐蚀

应用原子力显微镜（AFM）研究硫酸盐还原菌（SRB）、微生物膜、腐蚀产物膜和A3钢腐蚀后的表面形貌,获得了高分辨率、清晰的图像.测得了SRB的大小,微生物膜、腐蚀产物膜的厚度和形成的点蚀孔深度.结果表明,A3钢的微生物腐蚀过程是先形成致密的硫化物膜,然后微生物在其上面聚集附着形成微生物膜;A3钢的微生物腐蚀主要以点蚀形式发生.     

磁场对Q235钢微生物腐蚀行为的影响

采用腐蚀失重法、电化学测量技术和表面分析技术研究硫酸盐还原菌 (SRB) 在外加磁场下对Q235钢的腐蚀行为。结果表明,磁场条件下SRB对Q235钢的腐蚀作用较无磁场条件下减轻,其阻抗值先减小后增大,而无磁场条件下的阻抗值先增大后减小,说明磁场条件下试样表面的生物膜形成滞后。SEM的分析结果显示,磁场条件下Q235钢表面的生物膜均匀致密,并且紧密地黏附在金属表面。清除腐蚀产物后,无磁场条件下的基体表面呈现较多腐蚀孔和腐蚀裂缝,而有磁场条件下的基体表面则相对平整,说明磁场能有效地抑制SRB对Q235钢的腐蚀。     

船用钢的薄层液膜下腐蚀监测与防蚀研究

模拟907A钢在海水的饱和湿气环境中表面形成薄层液 膜状态下的腐蚀,利用恒电量腐蚀速率测量仪连接ACM探头,监测其腐蚀状态,结合电化学 阻抗谱(EIS)的测量,探讨907A钢在薄层液膜下的腐蚀机理,同时对薄层缓蚀剂液膜防蚀效 果作了快速评定.结果表明：907A钢在海水可见薄层液膜下腐蚀反应比完全浸泡在海水中的 腐蚀剧烈得多,虽然薄层缓蚀剂液膜对907A钢的缓蚀效率与全浸在缓蚀剂溶液中相比有一定 的差距,但相对于薄层海水液膜下的907A钢的腐蚀,薄层缓蚀剂液膜防蚀作用仍然是明显的 .     

利用丝束电极技术研究模拟微生物膜/金属界面的电化学不均匀性

利用丝束电极技术研究模拟微生物膜/金属界面局部腐蚀电位、腐蚀电流分布规律与膜内过氧化氢分布的相关性.海藻酸钙凝胶用来模拟微生物膜.结果表明,基于LabVlEW软件及模块化仪器构建的丝束电极测量装置,能快速、准确获得局部电极电位及电流信息.     

Corrosion control using regenerative biofilms (CCURB) on brass in different media

The corrosion behavior of cartridge brass (UNS C26000) exposed to artificial seawater (AS) and Luria Bertani (LB) medium has been studied using electrochemical impedance spectroscopy. Tests were performed in sterile media and in the presence of a Bacillus subtilis bacterial biofilm. Additional tests were performed in the presence of a B. subtilis bacterial biofilm that produced polyaspartate or a B. licheniformis biofilm that produced γ-polyglutamate. A significant reduction of corrosion rates and an ennoblement of the corrosion potential were observed in both media in the presence of the biofilms. Samples exposed in the presence of biofilms remained untarnished and unattacked for time periods exceeding one week, while samples exposed in the sterile solutions were covered with a dark film of corrosion products.     

海洋环境下金属冲洗缓蚀剂的评价

使用缓蚀剂冲洗是为了减缓船舶间隙部分的腐蚀问题.按冲洗缓蚀剂的工艺要求利用失重法来评价冲洗缓蚀剂,从10种商品化的缓蚀剂中筛选出有较好缓蚀效果的缓蚀剂ADD4、ADD5、ADD10,采用扫描电子显微镜(SEM)和X射线能谱(EDS)分别对浸过ADD5药剂的907A、921A钢表面的不同区域进行了形貌观察和成分分析,结果表明缓蚀剂在金属表面分布着较为均匀的条状物,正是吸附在这些腐蚀活性点上的条状物对金属起到了很好的保护作用.     

Influence of Static Low Electromagnetic Field on Copper Corrosion in the Presence of Multispecies Aerobic Bacteria

The effects of low electromagnetic field(EMF)( B = 2 mT) on the corrosion of pure copper in the absence and presence of multispecies marine aerobic bacteria were investigated in this work. The results showed that EMF has an inhibitory effect on copper metals and decreases the corrosion rate of copper metals in sterile artificial seawater. However, microbiologically influenced corrosion of Cu was increased in the presence of electromagnetic field due to its effect on the biofilm morphology and structure. EMF reduced the growth rate of bacteria and decreased bacterial attachment, thereby forming a heterogeneous and non-stable biofilm on the Cu surface in the presence of EMF. Moreover, the biofilm was dispersed throughout the surface after 7 days, whereas the scattered bacteria were observed on the surface after 10 days. Confocal laser scanning microscopy images showed large and deep pits on the surface in the presence of EMF and confirmed the acceleration of Cu corrosion in the presence of EMF and multispecies bacteria. Furthermore, XPS and FTIR results demonstrated that the corrosion products and metabolic by-products were significantly changed in the presence of EMF.     

热处理态NiCoCrAlY涂层的抗中性盐雾腐蚀性能

通过500 h中性盐雾试验研究了在低膨胀高温合金GH907上低压等离子喷涂(LPPS)的NiCoCrAlY涂层在热处理后的抗腐蚀性能,并与热处理态的LPPS制备的NiCr涂层的抗腐蚀性能进行了对比.结果表明,盐雾腐蚀500 h后,NiCoCrAlY涂层在扫描电镜下可以看到几个无破坏性作用的腐蚀坑,涂层表面仍保持较好的完整性和光洁性,对腐蚀产物的EDS面扫描表明腐蚀产物主要为Al的氧化物,涂层的腐蚀保护等级仅下降到9级;而NiCr涂层的表面出现了较多的腐蚀斑点,涂层的完整性和均匀性均已经被破坏,涂层表面产生了腐蚀裂纹,其腐蚀等级下降到4级.EDS分析表明腐蚀产物主要为Ni、Fe、Co等的氧化物.对比结果表明,NiCoCrAlY涂层表现出比NiCr涂层更强的抗中性盐雾腐蚀性能.     

The importance of live biofilms in corrosion protection

As observed before, Al 2024 was passive in artificial seawater (AS) in the presence of a protective biofilm of Bacillus subtilis WB600. When antibiotics were added to the AS to kill the bacteria in the biofilm, pitting occurred within a few hours as indicated by characteristic changes in the impedance spectra. The corrosion potential E_corr decreased at the same time to values observed in sterile AS. Addition of the antibiotics to sterile AS had no effect on corrosion behavior.     

907A、921A钢的抗冲刷腐蚀和磨蚀性能

采用旋转圆盘法对907A、921A钢在含有0.3%石英砂(200～300目)的3.5%NaCl溶液中的冲刷腐蚀和磨蚀性能分别进行测试,用失重法评价了2种材料的抗冲刷腐蚀和磨蚀性能,并利用扫描电镜观察了其腐蚀形貌.结果表明,921A钢在3.5%的NaCl溶液中的抗冲刷腐蚀性能及抗磨蚀性能均高于907A钢.     

Effect of oxygen and biofilms on crevice corrosion of UNS S31803 and UNS N08825 in natural seawater

The effect of oxygen and biofilms on crevice corrosion of UNS S31803 and UNS N08825 in seawater was studied. Passivity breakdown occurred through crevice corrosion in UNS N08825 and through transpassive dissolution in UNS S31803 although both alloys displayed crevice corrosion under potentiodynamic conditions. The most severe crevice corrosion occurred in the absence of oxygen and the presence of a biofilm. Microbial adhesion as investigated by fluorescence microscopy occurred mainly outside the crevice and DNA sequencing revealed a shift in biofilm composition as a function of substratum surface and oxygen pressure.     

Potential of biocorrosion in Danish district heatings sytems

Danish district heating (DH) systems utilise water with unique characteristics that include low conductivity, high pH, nutrient poor and anaerobic (oxygen free) conditions in order to reduce corrosion rates. This survey was carried out in order to investigate the potential for biofilm formation and biocorrosion in these systems. Determination of total bacterial numbers in water samples were performed in 29 DH systems and showed a range of 10²–10⁵ cells · ml^?1. The potential for biofilm growth was further examined in corrosion monitoring units located at 6 DH locations. Total bacterial numbers in biofilm on mild steel were found in the range of 10⁴–10⁶ cells · cm^?2. The mild steel coupons were examined for general corrosion rates based on weight loss together with an investigation of pitting corrosion. The general corrosion rates were up to 12 μm · year^?1, while the pitting analysis showed pit depths up to 90 μm for half a year of exposure. Presence of sulphate reducing bacteria (SRB) was found in all systems tested with corrosion monitoring units, whereas sulphide was found to different extents in the biofilms on all mild steel coupons. It was shown that DH systems with the highest number of bacteria in the biofilm generally had the most pronounced corrosion. The results show that despite the nutrient poor environment in the DH systems the potential for biofilm formation and biocorrosion was present.