Characteristics and formation of corrosion product films of 70Cu-30Ni alloy in seawater

The corrosion product films of 70Cu-30Ni alloy, composed of recrystallized grains or deformed and recrystallized grains, were investigated in 3.5% NaCl and natural seawater by electrochemical techniques, SEM, EDX and AES. The recrystallized alloy displayed a steady increase in the polarization resistance while the alloy of incomplete recrystallization kept its polarization resistance at a low level as increasing the immersion time in 3.5% NaCl. The films formed on the recrystallized alloy in seawater were thin, uniform and rich in nickel. After long-term immersion, the films, still thin and protective, consisted of convex lines and smooth zones between the lines. The convex lines were richer in nickel and contained more seawater species than the zones, so this led the lines to preferentially dissolve and new lines to appear where the film grew slower. Immersed in seawater, the alloy of incomplete recrystallization showed thick, loose and porous films, of which the inner layer was denickelified and the outer layer contained a great amount of seawater species, and of which the underlying substrate was found with severe intergranular corrosion. The tube specimens of incomplete recrystallization for four-year immersion were perforated by intergranular corrosion.     

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.     

天然海水微生物对5083铝合金初期腐蚀行为的影响

利用荧光电子显微镜,扫描电镜及能谱表面分析技术和开路电位,电化学阻抗谱,动电位极化电化学技术研究了在天然海水中浸泡初期,天然海水微生物对5083铝合金腐蚀行为的影响.结果表明,在天然海水中,铝合金表面形成良好的生物膜.电化学结果表明,在天然海水中铝合金腐蚀电位负移,点蚀电位正移,电荷转移电阻增大,说明短期浸泡时,天然海水生物膜的形成可以抑制其腐蚀,尤其对点蚀具有明显的抑制作用.在无菌海水中,随时间的增长,铝合金的腐蚀也受到一定程度的抑制,原因是锈蚀产物的形成对铝合金具有一定的保护作用.     

深冷处理对EH40极寒环境船用钢板的海水腐蚀性能影响

采用模拟浸泡实验技术,结合腐蚀形貌分析以及动电位极化和电化学阻抗技术研究了深冷处理对EH40极寒环境船用钢板在3.5%(质量分数)NaCl溶液中的海水腐蚀行为。结果表明:未经深冷处理的极寒环境船用钢板表面发生均匀腐蚀,在样品表面有均匀致密的腐蚀层产生;而经过-80℃深冷处理的钢板试样表面发生点蚀现象,其腐蚀失重增加,腐蚀速率由1.15 mm/a升至1.33 mm/a,增幅约为15.6%,同时腐蚀电流密度由1.244μA·cm^-2升至3.643μA·cm^-2,电化学阻抗值减小,耐蚀性降低;两者的腐蚀产物以α-FeOOH、β-FeOOH和γ-FeOOH为主。较低的环境温度对于极寒环境船用钢板的耐腐蚀性能有一定的影响。     

Microbial Activities’ Influence on Three Kinds of Metal Material Corrosion Behaviors

The corrosion behaviors of copper, 6063 aluminum alloy, and Q235 steel were investigated by open-circuit potential (OCP), anodic polarization curve analysis, and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy revealed that a small number of translucent rod-shaped bacterial colonies on the copper surface of copper, whereas plenty of rod-shaped microbes colony were detected on the surface of 6063 aluminum material. Moreover, rod-shaped bacteria and mold colonies attached to the surface of Q235 steel. The decrease in the OCP of copper, 6063 aluminum alloy, and Q235 steel led to higher corrosion tendency. EIS analysis showed that bacteria can reduce the value of AC impedance of copper, the polarization resistance, and the surface resistance, thereby accelerating corrosion. Moreover, the polarization resistance of aluminum alloy in bacterial seawater is lower than that in non-bacterial seawater, indicating the existence of bacteria accelerated the corrosion of 6063 aluminum alloy. The adherence of microbes on Q235 steel surface accelerated the dissolution of the surface layer, and then the passive film is replaced by incompact biofilm layer. Q235 steel corrodes faster under the influence of bacteria because the polarization resistance in bacterial seawater is much lower than that in non-bacterial seawater.     

添加双氧水对高强度低合金钢在海水中腐蚀影响的研究

通过动电位极化、激光Raman光谱、XRD和旋转环盘电极实验研究了高强度低合金钢在天然海水和含有0.01 mol/L H₂O₂的海水中的腐蚀规律,探讨了高强度低合金钢在加速体系与天然海水中的腐蚀机理。结果表明,添加H₂O₂使高强度低合金钢的自腐蚀电位正移、析氢电位负移、极限扩散电流密度增大,但锈层的相组成与天然海水中锈层组成相同。在2种体系中,钢的氧还原过程均为二电子反应控制过程。H₂O₂的添加明显加快了高强度低合金钢的腐蚀速率,但是不改变材料腐蚀机理。     

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。     

Dynamic electrochemical impedance spectroscopy and polarization studies to evaluate the inhibition effect of benzotriazole on copper‐manganese‐aluminium alloy in artificial seawater

The effect of benzotriazole (BTA) on the corrosion of a new type copper‐manganese‐aluminium (CMA) alloy in artificial seawater was investigated using dynamic electrochemical impedance spectroscopy (DEIS), linear polarization resistance, and Tafel extrapolation methods. Measurement results obtained from those three methods showed that corrosion rates decreased while BTA concentration increased. This clearly indicates that BTA inhibits the corrosion rate of CMA in artificial seawater. Although there are consistent results obtained from all these three methods, the results of the percent inhibition efficiency, IE (%), values obtained from DEIS method should be calculated from the charge transfer resistance (R_ct) values obtained after 5 h.     

冷喷涂铬锆铜涂层在海水中的耐蚀性能

采用冷喷涂技术在普通碳钢基体上制备了厚度为300μm的铬锆铜涂层,用扫描电子显微镜(SEM)观察涂层的组织形貌。用开路电位（OCP）、电化学阻抗谱和动电位极化曲线等电化学方法研究冷喷涂铬锆铜涂层在天然海水中的耐蚀性能。研究表明,铬锆铜涂层组织致密,在海水环境中,涂层表面形成一层致密的腐蚀产物膜,能有效阻止腐蚀介质向涂层内部渗透,对基体起到良好的保护作用。     

海水环境中弧菌对45钢腐蚀行为及力学性能的影响

通过热带海洋气候条件下在海水中培养弧菌,并对比45钢在自然海水、无菌海水和弧菌海水中的腐蚀行为,研究了弧菌对45钢腐蚀行为及力学性能的影响。结果表明,弧菌可以接种于海水中大量培养至高浓度(非培养基中培养),避免了培养基成分的缓蚀作用,从而更接近碳钢的自然腐蚀状态。海水中弧菌对45钢的平均腐蚀速率及力学性能有显著的影响。弧菌能加速45钢的平均腐蚀速率,但微生物的协同作用比单种弧菌更能加速材料的平均腐蚀速率。弧菌能显著降低局部pH值,引起材料表面严重的局部腐蚀,材料表面局部腐蚀促使其在拉伸过程中应力集中而发生断裂。     

16Mn钢在管输俄罗斯原油析出水中的腐蚀行为

采用浸泡失重、极化曲线、电化学阻抗谱、扫描电镜和能谱分析研究了管道16Mn钢在管输俄罗斯原油析出水中的腐蚀行为.管输俄罗斯原油析出水中主要的侵蚀性离子有氯离子和硫酸根离子.研究表明,16Mn钢在在析出水中的腐蚀主要表现为均匀腐蚀,腐蚀产物膜较致密,主要成分为Fb2O3.     

调整处理对17-4PH不锈钢耐海水腐蚀性能的影响

运用化学浸泡、极化曲线、循环极化曲线、电化学阻抗谱等方法研究了固溶后直接时效状态和调整＋时效状态的17—4PH不锈钢在人工海水中的耐蚀性能，并对显微组织作了观察和分析。结果表明，17—4PH不锈钢过调整处理后再进行时效处理，自腐蚀电位和点蚀电位升高而年腐蚀率下降，耐海水腐蚀性能全面优于直接时效态试样。其原因是17-4PH不锈钢经过调整处理后进行时效可避免贫铬区的形成，并使马氏体组织呈细小化特征，材料的组织均匀性提高。     

BP神经网络在碳钢、低合金钢海水腐蚀中的应用

根据实海环境数据及材料腐蚀数据,利用BP结构神经网络建立了碳钢、低合金钢在实海环境中腐蚀速度与环境因素、材料成份之间神经网络预测模型,并探讨了建立预测模型中遇到的一些问题.结果表明该模型可以较准确的预测碳钢、低合金钢在不同海域的腐蚀速度.      

Korrosionsverhalten des Stahls WL 1.3964

Corrosion behaviour of the Steel WL 1.3964 The non‐magnetizable austenitic steel X2 CrNiMnMoNNb 21 16 5 3, WL 1.3964 is used for the fabrication of special boats like submarines and minesweepers. The main reason for its application are its good corrosion resistance and its complete amagnetic properties. The steel WL 1.3964 does not corrode on plain surface when exposed to natural seawater, nevertheless there is a slight susceptibility of pitting and crevice corrosion. Based on the susceptibility of specific forms of corrosion the test program listed below was defined: Constant immersion of non‐coated and differently coated specimens in natural seawater. Crevice corrosion tests and polarization experiments with specimens of different surface treatments at different temperatures. The results may be summarized as follows: The steel WL 1.3964 may not be used in natural seawater without any protection because it has a certain susceptibility of pitting and crevice corrosion. A zinc‐rich coating system may protect the steel from corrosion. The steel WL 1.3964 has a certain susceptibility of corrosion in molten and re‐solidified areas and also in areas with heat discoloration which have not been properly post‐treated.     

Seawater corrosion of 70Cu‐30Ni alloy of incomplete recrystallization of intermittent and full immersion

The corrosion of 70Cu‐30Ni alloy of incomplete recrystallization was investigated by electrochemical technique, intermittent and full immersion in natural seawater, SEM and AES. Exposed to seawater for a short time, 70Cu‐30Ni alloy formed uniform and compact corrosion product films, which were rich in nickel, oxygen and seawater species for intermittent immersion; while the alloy fully immersed displayed loose and thick films, which were of denickelification and intergranular corrosion occurred to the underlying substrate. It was found that some regular crystals situated at the intersection of boundaries or the outer layer of the film and the crystals are ascribed to the reduction of cuprous ions to compensate the deficiency of oxygen for the cathodic process. Intergranular corrosion was observed in the underlying substrate for intermittent immersion after a long‐term exposure. Intermittent immersion can, to some degree, slow down the corrosion but not prevent the alloy of incomplete recrystallization from intergranular corrosion. Consequently, the corrosion mechanism of 70Cu‐30Ni alloy is proposed to be determined by its microstructure, independent of exposure conditions.     

船舶用Ti70合金在人工海水中的腐蚀行为研究

采用全浸腐蚀和电偶腐蚀实验,研究了Ti70合金的均匀腐蚀行为,以及与945钢的电偶腐蚀行为。结果表明：Ti70合金耐蚀性能极好,在60 ℃人工海水浸泡30 d后试样出现了轻微增重,腐蚀速率为-5.857×10^-4 mm/a,达到了I级完全耐蚀级别;Ti70合金自腐蚀电位远高于945钢,两者偶联时945钢将作为阳极被加速腐蚀;随着Ti70/945钢偶对面积比增加,945钢质量损失、以及电偶腐蚀电流和电偶腐蚀系数均逐渐增加,当两者偶对面积比为1∶1时,电偶腐蚀敏感等级达到了D级,因此当Ti70合金与945钢接触使用时需对945钢进行阴极保护。     

X70钢的滨海盐渍土-海水宏电池腐蚀

利用电化学阻抗测试技术等,研究了X70钢在滨海盐渍土与海水构成的宏电池中的腐蚀行为。结果表明,构成宏电池之后,海水侧X70钢一直作为宏电池的阳极处于被腐蚀状态,其腐蚀速率为自然腐蚀速率的25.3倍,腐蚀过程主要受阴极反应控制;由于腐蚀产物膜和氯离子的双重作用使宏电池腐蚀速率先有一定程度的降低,然后迅速升高,再有所降低并趋于稳定。试验还发现土壤-海水构成的宏电池的电动势并没有表现出像常规土壤宏电池电动势那样的先升高后降低的趋势,而是先有一定程度的降低,然后迅速升高后趋于稳定,该过程主要受极化电阻的影响。     

The effect of temperature on corrosion behavior of AA5083 in brackish water and seawater

Al‐alloy, AA5083, as a lightweight structural material with favorable mechanical properties and, compared with other lightweight materials, good corrosion resistance has an increased usage in the marine environment. It is well known that all Al‐alloys, including AA5083, in the presence of chloride ions are more prone to corrosion. Determination of corrosion behavior of AA5083 in seawater and brackish water has been investigated and compared at 18, 25, and at 30°C. To obtain more accurate and realistic results, fresh seawater and brackish water were sampled as an electrolyte in Sibenik region. The investigation was carried out using the following electrochemical methods: open circuit potential measurement, electrochemical impedance spectroscopy, linear polarization resistance, potentiodynamic polarization, and cyclic polarization. After potentiodynamic polarization measurement, each alloy was examined using a metallographic microscope to clarify corrosion morphology. Obtained results have shown that an increase in temperature leads to an increase in corrosion activity of AA5083 in both electrolytes, while microscopic examination reveals that the dominant type of corrosion is pitting.     

灰色理论对碳钢、低合金钢海水腐蚀的预测和分析

应用灰色理论中的GM（1,1）灰色模型和灰色关联分析预测了碳钢、低合金钢在青岛、厦门和榆林全浸区的海水腐蚀速率并研究了海水环境对腐蚀速率的影响.模型经后验差检验显示有很好的精度.通过灰色关联分析建立的海水环境和腐蚀速率关联度显示,海水腐蚀的主要影响因素是溶解氧浓度、pH值和平均盐度.     

Electrochemical corrosion behavior of X80 pipeline steel in a near‐neutral pH solution

In this work, the electrochemical corrosion behavior of X80 pipeline steel was investigated in a near‐neutral pH solution using electrochemical impedance spectroscopy (EIC) and photo‐electrochemical (PEC) measurements as well as X‐ray photo‐electron spectroscopy (XPS) technique. The effects of hydrogen‐charging and stress were considered. The results show that the steel is in an active dissolution state, and a layer of corrosion product is formed and deposited on the electrode surface, which is subjected to further oxidation to form ferric oxide and hydroxide. Photo‐illumination enhances anodic dissolution of the steel when it is under anodic polarization due to destroying of the corrosion product film. When the steel is under cathodic polarization, the cathodic current density decreases upon laser illumination due to the photo‐oxidation of hydrogen atoms generated during cathodic reactions, which behaves as an anodic reaction to offset the cathodic current density. Hydrogen‐charging and stress decrease the corrosion resistance of the steel and enhance the dissolution rate of the steel.