纯镁在中性1.0 mass%NaCl溶液中的腐蚀行为研究

以中性1.0 mass%NaCl溶液为研究体系,通过电化学阻抗(EIS)结合形貌分析研究了纯镁的腐蚀发展过程及其腐蚀机理.结果表明:该腐蚀过程可被分为典型的三个阶段,分别为腐蚀初期点蚀的产生与发展、氧化膜在阳极表面的堆积以及腐蚀后期氧化膜的破裂造成新的阳极区域的出现;随着腐蚀程度的逐渐深入,电极表面的粗糙度在不同阶段也有相应的增加;腐蚀过程中EIS分形维数的变化趋势与腐蚀形貌之间有良好的对应关系.     

电弧喷涂Al-Zn-Si-RE合金涂层在3.5%NaCl溶液中的电化学腐蚀行为(英文)

采用电弧喷涂方法在低碳钢表面获得高铝含量的Al-Zn-Si-RE涂层。通过测量Al-Zn-Si-RE涂层在3.5%NaCl溶液中的动电位极化曲线,腐蚀电位-时间曲线和电化学阻抗谱,系统地研究涂层的电化学腐蚀行为。通过将测量电化学阻抗谱拟合成等效电路图,研究涂层在3.5%NaCl溶液中浸泡不同时间的阻抗行为。结果表明:Al-Zn-Si-RE涂层与Zn-15Al涂层具有相似的极化行为,阳极极化曲线均无钝化特征,仅呈现出活性溶解,但其腐蚀性能优于Zn-15Al涂层。Al-Zn-Si-RE涂层可以给钢基体提供有效的牺牲阳极保护作用,且牺牲阳极保护作用在涂层腐蚀过程中占主导地位。此外,腐蚀电位-时间曲线和电化学阻抗谱结果表明:在浸泡过程中存在点蚀-溶解-再沉积、活化溶解、阴极保护、腐蚀产物引起的物理屏蔽和涂层失效五个腐蚀阶段。     

工业纯铝在3.5%NaCl溶液中的电化学阻抗谱分析

通过电化学阻抗谱（ＥＩＳ）测定,分析和研究工业纯铝在３．５％ＮａＣｌ中的电化学行为和腐蚀特征。研究结果表明,工业纯铝在３．５％ＮａＣｌ溶液中阳极极化电位较低时饨化膜完整,用抗呈现单容抗弧特征。Ｅ＞－０．８Ｖ,钝化膜开始局部破坏,ＥＩＳ图出现感抗弧。分析阳极极化过程阻抗的变化规律可以研究耐蚀性能和腐蚀机理。     

耐候钢在2.0%NaCl中性溶液中的腐蚀过程

采用电化学阻抗谱技术研究了耐候钢Q400NQR1和09CuPCrNi在2.0％NaCl中性溶液中的腐蚀行为,建立了其腐蚀等效电路模型并分析了其相关电化学参数随时间的演化规律,结果表明,两种耐候钢的溶液腐蚀过程均可以分为四个阶段,即点蚀诱导期、点蚀发展期、腐蚀中期和腐蚀后期;Q400NQR1较09CuPCrNi具有较高的抗溶液腐蚀能力,前者在腐蚀的中期生成保护性较强的内层锈层,而后者形成的内层锈层难以稳定且易于出现均匀腐蚀的现象。     

镀锡薄钢板在NaCl溶液中的腐蚀行为(英文)

应用电化学阻抗谱技术研究镀锡薄钢板在0.5mol/LNaCl溶液中的腐蚀过程,结合SEM、SPM、XRD、XPS技术表征腐蚀产物的形貌和腐蚀产物的结构。结果表明:腐蚀过程中镀锡层的电阻Rc值基本不变而电荷转移电阻Rct值下降了2个数量级,表明镀锡层基本没有发生腐蚀而基底金属碳钢则不断遭到腐蚀。镀锡薄钢板在0.5mol/LNaCl溶液中的腐蚀类型主要是对镀锡层缺陷处暴露的基底金属碳钢的腐蚀,其腐蚀产物主要是γ-FeOOH。     

电化学方法研究环氧涂层/基体在3.5%NaCl溶液中的腐蚀行为

采用电化学方法研究了两种常用涂层-环氧沥青涂层和环氧铝粉涂层在3.5%NaCl溶液中的腐蚀行为.腐蚀电位-时间结果表明,两种涂层的自腐蚀电位都比基体的更正,都能起到屏蔽作用保护基体,浸泡中电位向负方向移动说明活化腐蚀过程在继续.电化学阻抗结果表明,腐蚀介质能够较快的渗入涂层到达界面,使涂层的屏蔽作用降低,生成的腐蚀产物可在一定程度上抑制腐蚀的发展.并提出了两种涂层的等效电路模型,对阻抗结果进行了拟合.表明在浸泡初期涂层电阻随浸泡时间延长迅速降低,随后趋于稳定.指出电化学方法能获得与涂层性能有关的定量数据,非常适合于研究涂层/基体的性能.     

Ni-CeO2纳米镀层在酸性NaCl溶液中的腐蚀行为及电化学阻抗谱特征

借助超声辅助脉冲电沉积的方法在Watts-Ni电解液体系中制备了纳米晶纯Ni和Ni-CeO2复合镀层.采用电化学阻抗谱(EIS)测量和等效拟合电路解析,并结合静态浸泡腐蚀实验及其产物分析,研究了纳米CeO2颗粒对Ni镀层在3.5%NaCl+1.5%HCl(质量分数)混合水溶液(简称酸性NaCl溶液)中腐蚀性能的影响.结果表明:经600℃,4 h空气中的时效处理,可促使被填埋在镀层表面的稀土复合相沿晶界析出,并形成连续致密的弥散相钝化膜,填补并黏性钉扎由于电沉积析氢反应而遗留在镀层表面的微孔或热裂纹等缺陷,有效减少点蚀或晶间腐蚀的发生;动态极化曲线(Tafel)测定表明,纳米晶纯Ni和Ni-CeO2复合镀层在酸性NaCl溶液中均表现出明显的自钝化过渡区,后者自腐蚀电流较前者降低了近1.5个数量级;此外,EIS测试显示,纯Ni镀层的EIS由一个高频容抗弧和一个中低频扩散弧组成,时效处理前后Ni-CeO2镀层的EIS均呈现单一容抗弧特征,且相位角在更宽的频率范围内接近90°,从而表现出优异的抗腐蚀性能.在酸性NaCl溶液长期浸泡过程中,少量的Ce3+从CeO2弥散相中被还原释放出来作为缓蚀剂吸附在活性区域,提高了复合镀层的抗腐蚀性能;腐蚀形貌观察显示,Ni-CeO2镀层表面里现轻微的均匀腐蚀并被胶状不溶解的腐蚀产物所覆盖,而纯Ni镀层表面则出现了严重的点蚀现象;对腐蚀产物进行XRD和XPS测试分析表明,纯Ni试样表层主要积累了NiCl2和Ni(OH)2等腐蚀产物;而Ni-CeO2除含有上述这些主要产物之外,还包含CeCl3和CeO2等微溶相,覆盖并封堵点蚀源,可有效地阻止Cl-的扩散渗透行为.     

剥离涂层下的X80钢在鹰潭土壤模拟溶液中的腐蚀行为

构建了埋地管线钢在鹰潭土壤模拟溶液中的矩形缝隙剥离涂层模型,采用原位电化学测量方法对剥离区的X80钢进行电化学交流阻抗谱(EIS)表征,并对其腐蚀行为进行了研究.结果表明.腐蚀初期剥离区各位置的电化学反应特征相同、EIS由高频容抗弧和低频感抗弧组成.随着腐蚀反应进行,高频容抗弧半径增大.低频感抗弧消失.距漏点不同距离的X80钢试样的腐蚀程度有所区别:漏点处和剥离区底部的腐蚀最严重.为吸氧腐蚀和阳极溶解所致;剥离区中部腐蚀较弱,去除腐蚀产物的X80钢表面出现明显的点蚀坑,点蚀倾向加重,腐蚀类型由全面腐蚀向局部腐蚀转变.根据EIS规律和实验结果.剥离区的腐蚀进程可分为氧耗尽、阴离子迁移和腐蚀扩展3个阶段.     

(Al_2O_3-SiO_2)_(sf)／AZ91D镁基复合材料微弧氧化膜的制备及电化学阻抗谱分析

在硅酸盐电解液体系中,采用交流微弧氧化方法在增强体体积分数为33%的(Al_2O_3-SiO_2)_(sf)/AZ91D镁基复合材料表面制备出完整的保护性氧化膜.利用SEM,EDS和XRD分析了氧化膜的形貌、成分和相组成,测量了膜层的显微硬度分布.采用电化学阻抗谱(EIS)评价了微弧氧化表面处理前后复合材料的电化学腐蚀性能,确立了不同浸泡时间对应的等效电路.结果表明,微弧氧化膜主要由MgO和Mg_2SiO_4相组成,最大硬度达到1017 HV.氧化膜电化学阻抗模值|Z|与镁合金基体相比大幅度提高,耐腐蚀性能明显高于基体.在3.5%NaCl溶液里浸泡96 h后,EIS出现感抗弧,显示膜内部开始出现点蚀破坏.氧化膜耐蚀性由膜内致密层特性所决定.     

镍基固溶体增韧Cr_(13)Ni_5Si_2合金在含Cl~-溶液中的腐蚀行为

采用极化曲线,Tafel阿和电化学限抗谱(EIS)技术,研究了镍基固溶体增韧Cr_(13)Ni_5Si_2金属硅化物合金在不同Cl~-浓度Na_2SO_4+NaCl溶液中的电化学腐蚀行为,并对其表面钝化膜进行了X射线光电子能谱(XPS)分析.结果表明:由于超高的Cr含量易于在表面形成以Cr_2O_3为主的稳定钝化膜以及组成相Cr_(13)Ni_5Si_2和Cr3Ni5Si2高的化学稳定性,合金在不同Cl~-浓度溶液中均具有良好的耐蚀性;合金的开路电位,破裂电位和腐蚀电流密度等几乎不随Cl~-浓度的增加而改变,即合金对Cl~-浓度不敏感,在中性含Cl~-介质中耐蚀性优异.     

Initial corrosion behavior of pure zinc in simulated tropical marine atmosphere

The initial corrosion behavior of pure zinc in a simulated tropical marine atmosphere was investigated using gravimetric method, scanning electron microscope combined with energy dispersive spectroscopy (SEM-EDS), X-ray diffractometry (XRD), Fourier transform infrared spectrometry (FTIR) and electrochemical impedance spectroscopy (EIS). The kinetics of corrosion process is a decelerating process following the empirical equation D=Atⁿ (n<1). The protectiveness of the corrosion product layer could be attributed to the formation of simonkolleite, Zn₅(OH)₈Cl₂·H₂O, which could inhibit the rate determining step, namely charge transfer step, of the electrochemical corrosion process. A model of the evolution process of the product layers formed on zinc was proposed. In addition, the regularity of the corrosion rate of zinc as a function of the NaCl deposition rate can be described by a power function.     

Hg和Ga元素对Mg阳极材料组织和电化学腐蚀性能的影响(英文)

采用动电位极化、恒电流和交流阻抗测试方法研究了Hg和Ga元素对Mg2%Hg,Mg2%Ga和Mg2%Hg2%Ga合金电化学腐蚀性能的影响,并用扫描电镜、X射线衍射和能谱分析了上述合金的显微组织和腐蚀表面形貌。结果表明:Mg2%Ga合金是固溶体,Mg-2%Hg和Mg-2%Hg2%Ga合金的晶界有白色第二相。Mg-2%Ga合金的平均电位为1.48V,腐蚀电流密度为0.15mA/cm2,电化学活性差,耐腐蚀性能好。Mg-2%Hg-2%Ga合金的平均电位1.848V,腐蚀电流密度为2.136mA/cm2,电化学活性好,耐腐蚀性能差。MgHgGa合金的活化机制是Hg和Ga原子的溶解沉积。     

NaCl溶液中N80钢锈垢形成过程的电化学行为

利用线性极化、电化学阻抗谱及表面分析技术研究了N80钢在NaCl溶液中腐蚀锈垢形成过程的电化学行为。结果表明,随着锈垢的形成,腐蚀过程由电化学控制转变为扩散控制,电荷传递电阻及扩散电阻减小,阻抗扩散部分直线与实轴夹角逐渐减小。提出了试样表面锈垢的物理模型,解释了锈垢层疏松多孔特性与阻抗谱特征之间的相关性。腐蚀锈垢分为两...     

Electrochemical noise characteristics in corrosion process of AZ91D magnesium alloy in neutral chloride solution

The corrosion process of AZ91D magnesium alloy in neutral 1% (mass fraction) sodium chloride aqueous solution was investigated by electrochemical noise(EN), SEM and EDX. Fractal theory was primarily used to depict the corrosion process of the alloy. The fast wavelet transform(FWT), as well as the fast Fourier transform(FFT), was employed to analyze the EN data. The results show that the overall corrosion process can be described by three stages. The first stage corresponds to the pit nucleation and growth; the second stage involves the growth of a passive oxide layer; and the third stage involves reactivation. With increasing immersion time, fractal dimension increases fast initially, fluctuates in the medium and increases again at last. Pitting corrosion and fractal dimension increase due to the initiation and formation of pits in the initial and the end of immersion, while depresses due to the passivation in the medium period. The results of SEM and EDX support the above conclusions.     

Electrochemical corrosion response of a precipitation hardening moulds steel in a NaCl solution

Investigations concerning the electrochemical corrosion behavior of mould steels are scarce and limited. In the present study, the corrosion resistance of a precipitation hardening moulds steel submitted to aging treatments has been assessed in a 0.1 M NaCl aqueous solution by means of potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The electrochemical characterization of the steel not submitted to hardening treatments was also examined and a comparative study was made between the different specimens. Scanning electron microscopy and electron probe microanalysis were used to obtain information about the morphology and chemical composition of the steels surface after the electrochemical tests. Increasing the aging temperature an increase of secondary hardness is observed, attributable to an increase of secondary phases (re‐precipitated carbides and metastable GP zones) amount, positively reflecting on the mechanical properties. However, the electrochemical results show a progressive worsening of the corrosion behavior, the as‐received steel sample exhibiting the best corrosion resistance. The observed decrease of corrosion resistance with increasing the aging temperature is ascribed to enhanced galvanic coupling phenomena between the secondary phases, acting as cathodes, and the surrounding matrix which, consequently, experiences preferential dissolution.     

Exfoliation corrosion of 7150 Al alloy with various tempers and its electrochemical impedance spectroscopy in EXCO solution

The exfoliation corrosion susceptibility and electrochemical impedance spectroscopy (EIS) of 7150 Al alloys with T6, T73, and RRA (retrogression at 175 °C for 3 h) tempers in EXCO solution were investigated. The anodic equilibrium precipitate η(MgZn₂) is continuous or closely spaced at the grain boundaries in the 7150‐T6 Al alloy, resulting in its greatest susceptibility to exfoliation corrosion. The grain boundary η precipitates in the RRA and T73 treated 7150 Al alloys are coarsened and show a clear discontinuous nature; they possess similar exfoliation corrosion sensitivity and their exfoliation corrosion resistance is greatly increased. At the beginning of immersion in EXCO solution, the EIS plot of the 7150 Al alloys is composed of a capacitive arc in the high to medium frequency range and an inductive component in the medium to low frequency range. As immersion time is increased, exfoliation corrosion with different corrosion ratings occurs on the surface of the 7150 Al alloy with various tempers, two capacitive arcs appear in the high to medium and medium to low frequency ranges, respectively. The fitted medium to low frequency capacitance C₂ of 7150‐T6 Al alloy, corresponding to the new surface caused by the exfoliation corrosion, is much greater than that of the T73 and RRA treated 7150 Al alloy, which is consistent with the greatest exfoliation corrosion susceptibility of the 7150‐T6 Al alloy.     

LC4铝合金在氯化钠溶液中的孔蚀特征

LC4铝合金在 2 .0 %NaCl溶液中发生局部腐蚀的过程中 ,电位噪声的谱功率密度 (SPD)曲线具有相同的特征 ,即在极低频下为白噪声 ,随着频率的升高逐渐转化为 1/fa 噪声 ,相应于一个噪声信号波 ,有一个腐蚀孔出现。在孔蚀诱导期 ,白噪声水平升高 ,截止频率增大 ,SPD曲线的倾斜段直线斜率小于 - 2 5dBv/Hz ,且趋于增大。孔蚀发生后 ,上述 3个参量则各自朝着上述方向的逆方向变化。实验发现 ,孔蚀参数SE 和SG 可以正确的表征孔蚀的发生、发展及材料的均匀腐蚀。阻抗测量结果表明 :孔电阻在刚开始浸泡时较大 ,随后减少渐趋于平稳 ,最后孔电阻又升高。这是因为随着浸泡时间的增加 ,孔面积渐渐增大 ,浸泡 6 5 0 0 0min时 ,孔电阻有所上升 ,可能是由于母孔内子孔的形成所致。产物电阻逐渐稳定上升 ,表明腐蚀产物逐渐增多。