温度对P110钢CO2腐蚀行为的影响

在模拟油田实际腐蚀环境中研究了温度对P110钢CO2腐蚀行为的影响．用SEM、XRD等分析了在不同温度条件下材料表面腐蚀产物膜的形貌以及对腐蚀速率和腐蚀形态的影响．结果表明，40℃时表层腐蚀产物类似于疏松的土壤，少且很松散地附着在材料表面，成份主要是溶液中沉积的KCl.90℃时腐蚀产物主要是钙铁镁的碳酸盐和少量的KCl和Fe2O3，腐蚀产物呈颗粒状，较致密但是膜层中含有大量的孔洞．140℃时，试样表层腐蚀产物呈致密的粘土形貌、下层腐蚀产物仍是颗粒状，产物层致密，成份主要是FeCO3和KCl．不同温度下不同的腐蚀产物形貌造成随温度升高。材料的平均腐蚀速率在90℃时出现峰值．     

钢的高温高压CO2腐蚀产物膜研究进展

综述了近期国内外在CO2腐蚀产物膜方面的研究进展.其中重点阐述了钢在高温高压CO2环境中腐蚀产物膜的形成机理、主要影响因素、结构沉积过程,力学性能及电化学行为等,并讨论了有关CO2腐蚀产物膜方面的研究方向与内容.     

高温高压下CO2对N80钢的腐蚀实验研究

针对N80钢的CO2腐蚀性能,模拟大庆油田井下的腐蚀环境,通过高温高压釜进行了N80钢的腐蚀实验,采用SEM、XRD分析研究所获得的CO2腐蚀产物膜的形貌和化学组成.结果表明,在本试验条件下,N80钢CO2腐蚀产物膜对基体具有一定的保护作用,可以降低腐蚀速率.N80钢的腐蚀膜主要是由晶态FeCO3构成的,同时含有一定量的(Fe,Ca)CO3复盐,还夹杂着少量单质Fe.     

N80钢CO2腐蚀产物膜研究

在模拟油田CO2腐蚀环境下，用XRD、EDS和SEM研究了N80钢腐蚀产物膜的形成与发展情况。结果表明，在本试验条件下N80钢CO2腐蚀产物膜对基体具有一定的保护作用，可以降低腐蚀速率。腐蚀产物膜分3层，讨论了3层膜的结构特征与形成机理。初步研究了腐蚀产物膜的破坏特征。腐蚀产物膜的晶体类型是（Fe,Ca)CO3复盐。     

阳离子对P110钢高温高压CO2腐蚀反应过程的影响

运用腐蚀失重、腐蚀表面成分分析和电化学测量技术，研究了在高温高压条件下阳离子对P110油管钢CO2腐蚀行为的影响.结果表明：随着试验时间的延长，阳离子的存在使得电极反应速率降低较慢，它不仅通过在金属表面成膜影响腐蚀反应的阳极过程，而且同时改变了腐蚀反应的阴极过程；在反应初始阶段EIS具有2个时间常数，电极反应由活化控制，随着腐蚀的进行，腐蚀产物膜越来越厚，越来越致密，EIS的低频端出现Warburg阻抗与容抗的叠加，自腐蚀电位下的电极反应属于混合控制；溶液中是否含有Ca2+、Mg2+离子，在P110钢腐蚀成膜过程中EIS存在一定的差别，并且使阻抗谱拟合结果在相同的腐蚀时间内产生很大的变化.      

KO110与3Cr110钢的CO2腐蚀实验对比研究

在模拟油田CO2腐蚀环境下，对K0110钢和3Cr110钢的腐蚀特征进行研究并加以比较。结果表明，两种钢的腐蚀速率在90℃左右都达到最大值；在温度低于90℃时表面形成的膜较疏松，保护性差；而温度高于90℃时，形成的膜和基体接合较为牢固，保护性强；钢中铬的加入能有效地防止局部腐蚀的发生。     

N80油套管钢CO2腐蚀阴极过程电化学阻抗谱分析

利用电化学阻抗（EIS）技术研究了N80钢在不同介质条件下CO2腐蚀过程中可能存在的阴极反应及其反应速度。结果表明，N80钢在CO2腐蚀环境下存在H^ 和H2O以及H2CO3，HCO36-的还原反应，但在不同条件下各个还原反应的速度并不相同，在酸性的饱和和CO2溶液中，H^ 的还原控制着阴极反应速度，HCO3^-和H2CO3的珲原反应速度较小；在中性的饱和CO2溶液中，阴极过程以HCO36-和H2CO3的还原为主，H^ 的还原反应速度比较微弱；在碱性的NaHCO3溶液通入CO2后，HCO3^-的还原控制着阴极反应速度，在以上条件下，H2O的还原速度比较微弱，还不会对阴极交换电流产生影响。     

氮元素对2Cr13不锈钢CO2腐蚀产物膜结构和电化学性能的影响

利用高温高压釜进行2Cr13不锈钢的高温高压CO2腐蚀实验,用扫描电镜（SEM）和X射线光电子谱（XPS）分析腐蚀产物膜的形貌和成分,电化学交流阻抗谱测试腐蚀产物膜对2Cr13不锈钢电极过程影响,失重法评价两种2Cr13不锈钢CO2均匀腐蚀速率．结果表明：含氮钢的腐蚀产物膜结构比较疏松,腐蚀膜中的Cr2O3被CrN和Na3CrO4部分替代,并且含有较多的Fe3O4和α—FeOOH,其膜的电阻值比不含氮的2Cr13钢的小,腐蚀速率较大．     

钙离子对NC-55E钢CO2腐蚀产物膜性能的影响

通过线性极化、电化学阻抗谱测试和SEM观察,研究了80℃条件下Ca2+浓度对NC 55E套管钢CO2腐蚀产物膜的形成过程及其保护性能的影响.结果表明,随Ca2+浓度增加,Rp和根据阻抗谱拟合所得的Rf的最大值逐渐增大;在4%的CaCl2溶液中生成的腐蚀产物膜相对更具有保护性;从4%CaCl2腐蚀产物膜的表面和截面形貌可以看出,在浸泡40 h左右,腐蚀产物膜保护性能最好,61 h时,腐蚀产物膜开始发生局部腐蚀而发生破坏;在相同的Cl-浓度条件下,Ca2+的加入降低了金属的腐蚀速率,可以延长腐蚀产物膜的破坏时间,延缓腐蚀的发生.     

X65钢CO2腐蚀产物膜形成机理

用X-射线衍射（XRD）和扫描电子显微分析（SEM）技术研究了X65钢在模拟油田CO：腐蚀环境下腐蚀产物膜的形成与生长过程。结果表明：腐蚀产物膜分为三层，表层由FeCO3等轴晶粒构成；中间层由棒状晶粒构成，且充满孔洞；最内层由致密的FeCO3晶粒构成。三层膜的形成机理为最初的腐蚀过程是钢基体溶解，继而形成Fe3C架构，并在其表面沉积FeCO3晶粒，CO32^-和HCO3^-向内扩散与钢基体直接反应形成中间层和最内层。     

Exfoliation corrosion susceptibility of 8090 Al-Li alloy examined by electrochemical impedance spectroscopy

The exfoliation corrosion susceptibility and electrochemical impedance spectroscopy(EIS) of rolled and peak-aged 8090 AI-Li alloys in EXCO solution were studied, and the EIS after exfoliation was simulated. Once exfoliation occurs, two capacitive arcs appear in the EIS at high-mediate frequency and mediate-low frequency respectively. The exfoliation-attacked alloy surface consists of two parts, an original flat alloy surface and a new interface exposed to EXCO solution due to the exfoliation. The capacitance corresponding to the new exfoliation inter-face increases approximately linearly with time at early exfoliation stage, due to the enlargement of the new inter-face.Then it maintains stable, due to the corrosion product covering on the new inter-face. The exfoliation susceptibility can be judged through the average slope of the capacitance vs time curve of the early exfoliation stage. This average slope of the rolled 8090 alloy is much higher than that of the peak-aged 8090 alloy, accordingly the rolled 8090 alloy is more susceptible to exfoliation than the peak-aged 8090 alloy.     

Corrosion performance of high pressure die-cast Al-6Si-3Ni and Al-6Si-3Ni-2Cu alloys in aqueous NaCl solution

The corrosion performance of high pressure die-cast Al-6Si-3Ni (SN63) and Al-6Si-3Ni-2Cu (SNC632) alloys in 3.5% (mass fraction) NaCl solution was investigated. X-ray diffraction (XRD) and microstructural studies revealed the presence of single phase Si and binary Al₃Ni/Al₃Ni₂ phases along the grain boundary. Besides, the single Cu phase was also identified at the grain boundaries of the SNC632 alloy. Electrochemical corrosion results revealed that, the SNC632 alloy exhibited nobler shift in corrosion potential (?_corr), lower corrosion current density (J_corr) and higher corrosion resistance compared to the SN63 alloy. Equivalent circuit curve fitting analysis of electrochemical impedance spectroscopy (EIS) results revealed the existence of two interfaces between the electrolyte and substrate. The surface layer and charge transfer resistance (R_ct) of the SNC632 alloy was higher than that of the SN63 alloy. Immersion corrosion test results also confirmed the lower corrosion rate of the SNC632 alloy and substantiated the electrochemical corrosion results. Cu addition improved the corrosion resistance, which was mainly attributed to the absence of secondary Cu containing intermetallic phases in the SNC632 alloy and Cu presented as single phase.     

含钪Al-Cu-Li-Zr合金的剥蚀性能及电化学阻抗谱

采用剥落腐蚀(Exfoliation corrosion,EXCO)实验和电化学阻抗测试方法,研究时效对新型含钪Al-Cu-Li-Zr合金剥蚀性能的影响。结果表明:合金在EXCO溶液中剥落腐蚀敏感性由高到低的顺序为过时效,峰时效,欠时效;合金在EXCO溶液中浸泡初期,其电化学阻抗谱由一个高频容抗弧和低频感抗弧组成,且随浸泡时间的延长,低频感抗部分逐渐减弱直至消失;一旦发生剥蚀,合金的电化学阻抗谱出现两个部分重叠的容抗弧。依据腐蚀特征和电化学原理设计了等效电路图,对合金腐蚀发展过程的电化学阻抗谱进行了拟合,拟合数据和实验结果一致。     

N80钢CO2腐蚀电极过程交流阻抗分析

利用交流阻抗技术研究了N80钢在不同介质条件下CO2腐蚀交流阻抗图谱的特征，结果表明，N80油套管钢CO2腐蚀EIS曲线具有三个时间常数，其中低频感抗弧与试样表面活化溶解有关，低频容抗弧与试样表面腐蚀产物膜生成有关。随着试样表面腐蚀产物膜覆盖度增大，EIS曲线低频区感抗弧逐渐缩小，容抗弧逐渐扩大。进一步讨论了试样表面腐蚀产物膜成膜情况与电极反应过程的有关。     

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.     

Two‐step electrosynthesis of polypyrrole for corrosion protection of stainless steel

Smooth polypyrrole (PPy) films were successfully electrosynthesized on a stainless steel (SS, 1Cr18Ni9) surface by a self‐catalytic two‐step process. SS substrate dissolution during PPy electrosynthesis was effectively depressed. The redox properties and corrosion behavior of PPy film coated SS electrodes were investigated by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization. The reduction of PPy was found to include two reaction processes: an anion dedoping process and a cation insertion process. The PPy film was found to lose its electroactivity when polarized at high potentials due to peroxidation. EIS of SS/PPy mainly corresponds to PPy film response and charge transfer resistance decreases as film thickness increases, indicating that SS corrosion can be inhibited effectively by the PPy film.     

Erosion resistance of CO2 corrosion scales formed on API P110 carbon steel

The erosion resistance of CO₂ corrosion scales formed on carbon steel was investigated in water–sand two-phase flow utilizing weight loss test, scanning electron microscopy, and X-ray diffraction. The effects of CO₂ partial pressure, stirring speed, test time, and grain size on the erosion resistance of the scales were analysed. Results show that several characteristics of CO₂ corrosion scales are key factors affecting erosion resistance. Cubic polynomials are used to fit the erosion rate data, and effectively evaluate the ability of CO₂ corrosion scales to resist erosion. An erosion mechanism, based on fluid dynamics and CO₂ corrosion scales characteristics, is discussed.     

The inhibitive effect of 5‐amino‐indole on the corrosion of mild steel in acidic media

The inhibitor performance of 5‐aminoindole (5‐AI) on mild steel corrosion in 0.5 M HCl was investigated in relation to the inhibitor concentration using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and linear polarization (LPR) methods. The effect of immersion time on the corrosion behavior of mild steel was also studied. The impedance data obtained were fitted and modeled using an equivalent circuit model. The results show that 5‐AI is an effective inhibitor and has an inhibition efficiency of 90% at 1 × 10^?2 M additive concentration. The adsorption behavior of 5‐AI was also investigated. For this purpose, the adsorption equilibrium constant (K_ads), and the free energy of adsorption (ΔG_ads) were calculated and discussed. It was found that 5‐AI acts as mixed‐type inhibitor and obeys Langmuir adsorption isotherm with a free energy of adsorption of ?27.71 kJ/mol.     

The corrosion behavior of carbon steel in CO2‐saturated NaCl crevice solution containing acetic acid

The corrosion behavior of X52 carbon steel electrodes in CO₂‐saturated NaCl crevice solution containing HAc was investigated by electrochemical measurements. Chemical environment measurements by Cl^? and pH microprobes show an enrichment of Cl^? ions and an increase of pH values inside the crevice. Moreover, both increments could accelerate with the decreasing dimension of the crevice mouth due to the high diffusive resistance. When the electrode in the crevice solution is coupled with the electrode in bulk solution, the alkalization and the enrichment of Cl^? ions in the crevice solution can result in a negative shift of potential of the electrode in crevice solution, while the potential of the electrode in bulk solution shifts positively during the corrosion process. Thus, a galvanic corrosion is established with the electrode in the crevice solution acting as anode while another in the bulk solution as cathode, i.e., the corrosion in the crevice solution was enhanced while the corrosion in the bulk solution was retarded. The anodic dissolution and the cathodic reduction processes dominate in the crevice solution and in the bulk solution, respectively.     

不同腐蚀介质中16Mn钢高温高压腐蚀行为的比较

采用高压釜研究了16Mn钢在含有CO2与CO2+H2S介质的NACE(5wt%NaCl+0.5wt%CH3COOH)溶液中的高温高压腐蚀行为,利用失重法计算了腐蚀速率,通过SEM,XRD,EPMA等手段分析了腐蚀产物的成分及结构。结果表明:CO2腐蚀产物主要为Fe3C;CO2+H2S腐蚀产物主要为FeS,60℃时有FeCO3形成,腐蚀主要显示以CO2腐蚀为主的点蚀特征,90~120℃时,腐蚀系统以H2S腐蚀为主导,腐蚀产生的鼓泡、阶梯状裂纹是CO2与H2S协同作用的结果,CO2会增大H2S腐蚀的敏感性,使腐蚀产生氢损伤的温度提高。