Cr13钢在含CO_2油田采出液中腐蚀行为的实验研究

采用静态电化学测试和动态高温高压腐蚀方法,研究了Cr13钢在含CO_2的油田采出液中的腐蚀行为,分析了Cl~-浓度和温度对Cr13钢CO_2腐蚀性能的影响规律,分析了扫描电镜腐蚀形貌。结果表明:Cr13钢在含CO_2的油田采出液中呈现出明显的钝化行为,随着温度的增加,Cr13钢钝化电流密度呈现先增加后降低的趋势,60℃时达到极值;随着Cl-浓度的增加,Cr13钢钝化电流增加,耐蚀性降低;这主要是由表面膜层疏松程度不同所导致的。     

高氮钢在含Na_2S饱和CO_2溶液中的腐蚀电化学行为

通过电化学测试方法,对高氮钢在含Na_2S饱和CO_2溶液中的腐蚀电化学行为进行研究,得到高氮钢的钝化稳定性和腐蚀规律。在含Na_2S的饱和CO_2腐蚀介质中,Cr13的钝化膜表面载流子密度最大,钝化稳定性最差,耐蚀性最差,316L钢较好,高氮钢最优。随着Na_2S浓度的增大,高氮钢的点蚀电位下降,钝化区间变窄,维钝电流变大,钝化膜层的电荷传递电阻降低,高氮钢钝化稳定性能变差,耐蚀性变差。随着温度的升高,高氮钢的自腐蚀电位和点蚀电位均下降,维钝电流增大,钝化膜表面的载流子浓度也增大,且其电荷传递电阻和膜层电阻也降低,钝化稳定性下降。     

CO2环境中醋酸对X65钢湿气管线顶部腐蚀行为的影响

为研究延长气田CO₂环境中醋酸对X65湿气管线顶部腐蚀的影响，通过自制顶部腐蚀模拟实验装置以及动电位极化曲线和电化学阻抗法，采用挂片失重、扫描电镜分析手段研究了CO₂环境中醋酸对X65电化学腐蚀行为的影响。结果表明，腐蚀介质pH与HAc质量浓度呈对数函数变化，HAc质量浓度升高则腐蚀电流密度变大，阴极反应增强，腐蚀产物膜的溶解性增加，易产生孔隙，诱发氧浓差腐蚀。不同HAc质量浓度下，EIS高频容抗弧与界面双电层的行程有关，EIS低频斜线与腐蚀介质扩散有关。内层腐蚀产物膜与基体结合界面凌乱。HAc质量浓度增加，顶部腐蚀速率增加，腐蚀速率与HAc质量浓度呈对数函数关系。     

XS-1型缓蚀剂对2Cr13钢和N80钢缓蚀性能的影响

利用失重法,借助高温高压H_2S/CO_2腐蚀反应釜,研究了XS-1型耐高温新型抗氧缓蚀剂在NaCl介质中的缓蚀性能。通过正交实验法,分析了介质温度、Cl~-浓度、缓蚀剂浓度对2Cr13不锈钢和N80套管钢腐蚀行为的影响。结果表明:Cl~-浓度是影响两种钢腐蚀的主要因素,缓蚀剂浓度的影响力度略小于Cl~-浓度的影响力度。XS-1型缓蚀剂适用于Cl~-浓度高、酸化程度高和温度高的地层液中。     

氮对Cr13钢组织及耐CO_2腐蚀性能的影响研究

以Cr13钢为母材,采用真空等离子电弧炉制备不同含氮量的Cr13合金,分析氮含量对其金相组织和维氏硬度的影响,并通过电化学测试研究制备合金在含CO2腐蚀介质中的腐蚀行为,分析其耐蚀机理。研究表明:含氮Cr13钢组织为黑色索氏体和共晶莱氏体,氮的加入减少了δ铁素体含量,增加了奥氏体含量,合金组织均匀,无明显偏析;氮的加入(由于其固溶强化作用)改善了Cr13钢的机械性能,提高了钢的硬度,并随着氮含量的增加,其硬度增大;含氮Cr13钢在含CO2腐蚀介质中维钝电流较小,击穿电位较大,钝化稳定性增大,耐腐蚀性提高。     

高密度ZnBr_2/CaBr_2溴盐缓蚀剂的筛选及缓蚀性能测试

针对Zn Br2/Ca Br2溴盐溶液腐蚀机理,以FTD为基础,对Zn Br2/Ca Br2溴盐缓蚀剂进行复配筛选,确定了一个较好的抗溴盐腐蚀的缓蚀剂配方:0.2%FTD、0.8%MOS、0.2%丙炔醇、0.4%吗啉和0.2%TTC。采用室内静态挂片失重法测定了复配缓蚀剂在不同温度、不同密度溴盐溶液中对P110钢和13Cr钢的缓蚀性能。结果表明,经低温85℃和高温180℃不同密度(1.8、2.0、2.1 g/cm3)Zn Br2/Ca Br2溴盐溶液浸泡20 d后,13Cr钢基本无腐蚀;P110钢的腐蚀速率随着温度的升高而增大,随着溴盐溶液密度的减小而增大。     

Zn／A3钢在海水中电偶腐蚀的研究

研究了金属Zn与A3钢在海水中偶接时的电偶腐蚀行为。考察了偶接时间、溶液中Cr浓度、电偶对中阴阳极面积比、实验温度等因素对阳极腐蚀速度的影响。结果表明：偶接时间为24h时,腐蚀速度趋于稳定。腐蚀速度随温度升高,溶液中Cr浓度的增大;阴阳面积比的增大,A3钢的腐蚀速度会相应减慢。     

工业纯钛的缝隙腐蚀探讨

采用10％FeCl3·6H2O溶液和1mol／L硫酸溶液进行不同温度下的浸泡试验,以3．56％NaCl溶液和1mol／L硫酸为介质,进行不同条件下的电化学测试,对钛的缝隙腐蚀行为进行研究。实验结果表明温度对缝隙腐蚀有较大的影响：在10％FeCl3·6H2O介质中,当温度低于50℃时未发生缝隙腐蚀,当温度高于80℃,缝隙腐蚀随温度升高而增大;在1mol／L硫酸介质中,缝隙腐蚀随温度的升高而加剧;在10％FeCl3·H2O介质中,临界缝隙尺寸随温度的升高而增大。在氧化性的三氯化铁介质中的缝隙腐蚀速率明显小于还原性稀硫酸介质中的缝隙腐蚀速率。     

A3钢在不同CO2盐溶液中的腐蚀规律研究

通过静态、动态及电化学实验方法测试不同含盐量溶液中饱和二氧化碳对A3钢的腐蚀影响,以及溶液中Ca2 和S2-对A3钢的腐蚀影响。研究结果表明,NaCl质量分数50g/L时,腐蚀速率最大;温度在60℃时腐蚀速率最大;腐蚀速率随CO2分压的升高而增大;Ca2 离子的存在减缓了腐蚀;S2-离子的存在减缓了腐蚀。本文从静态、动态及电化学测试的不同方面入手,评价CO2在不同介质条件下的腐蚀规律,了解CO2腐蚀性与介质的关系,对现场如何采取防腐措施具有一定的指导作用。     

1Cr13不锈钢应力腐蚀裂缝内的电化学机制研究

模拟1Cr13不锈钢在0.5mol/L NaCl溶液中应力腐蚀裂缝尖端的环境变化和受力状态,进行腐蚀及电化学测试,绘制了描述该体系应力腐蚀裂缝内各阶段热力学和动力学行为的实验电位～pH图.腐蚀率～pH曲线、电位～时间曲线和电位～pH图等均表明上述体系应力腐蚀裂缝内存在1个临界pH值(90℃时约为4.1).低于临界值,裂缝尖端发生钝态向活态的转变,腐蚀速度骤增,电位下降.应力和微区酸化都使裂缝内的钝化效果变差,腐蚀率增大.应力使裂缝尖端开始加速腐蚀的临界pH值升高.     

Hydrogen absorption into Grade-2 titanium during crevice corrosion

Hydrogen absorption into ASTM Grade-2 titanium (Ti-2) under actual crevice corrosion conditions was studied using a galvanic coupling technique. The alloy's iron content and its distribution in Ti-2 had a marked effect on the accumulation of crevice corrosion damage and the maximum depth of penetration. Iron present in intermetallic precipitates appeared to suppress crevice propagation and to limit the maximum depth of penetration by catalyzing the proton reduction reaction inside the crevice. Crevice corrosion initiated more rapidly, and the rate of activation of propagation increased, as the temperature was increased over the range 85–135 °C. However, the extent of overall crevice corrosion decreased with increasing temperature. Both the total amount of damage accumulated and the maximum penetration depth increased with increasing chloride concentration over the range of 0.27–2.5 mol dm⁻³, whereas in 5.0 mol dm⁻³ NaCl solution, the amount of crevice corrosion damage was much less. Additionally, both a high temperature and a high Cl⁻ concentration tended to lead to the localization of crevice propagation at a small number of active sites. A relatively constant hydrogen absorption efficiency of 5–8% was obtained, indicating that hydrogen absorption into Ti-2 under crevice corrosion conditions is insensitive to the duration of propagation, the temperature, and the Cl⁻ concentration.     

Consideration of the formation of solids and gases in steady state modelling of crevice corrosion propagation

One of the challenges in the simulation of crevice corrosion propagation is the rigorous treatment of non-aqueous species (gas or solids), since the appearance of a new phase in a crevice will automatically have an impact on its geometry. This paper presents a simple approach, where heterogeneous reactions are considered in a post-processing step, by determining the conditions of potential, external chemistry (pH, chloride, …) or geometry under which gas or solid phases could appear in the crevice. Thus, as function of these conditions, stability diagrams for the different phases that are liable to appear in an actively propagating crevice can be constructed. Such diagrams (e.g. dimension variable or external chloride concentration versus applied potential) allow the delineation of an homogenous domain where the crevice propagates steadily, with a rate systematically higher at the mouth than at the bottom. The transition from an homogeneous to an heterogeneous phase domain, corresponding to the appearance of precipitates (ferrous hydroxides or ferrous chloride) or gas (hydrogen) within the crevice, is discussed in the light of experimental results reported in the literature with artificial crevices.     

The influence of nickel-aluminium bronze microstructure and crevice solution on the initiation of crevice corrosion

A new mechanistic model has been established for the chemical and electrochemical mechanisms controlling nickel-aluminium bronze crevice corrosion. The crevice corrosion was initially confined to eutectoid regions with slight attack of the copper rich α-phase within the α+κ_III eutectoid. In the presence of high chloride concentrations, copper and aluminium complexes form and the hydrolysis of these complexes leads to the acidification of the crevice solution chemistry. As the crevice solution becomes increasingly acidic the initial protection of the κ-phases due to their higher aluminium contents is lost and become anodic to the α-phase. The continuous nature of the κ_III-phase makes it vulnerable with an ∼80 μm depth of attack after only the first month which is accompanied by internal copper redeposited at cathodic sites. Crevice corrosion of copper-based alloys is often reported to be controlled by a copper-ion concentration cell, however, for nickel-aluminium bronze it appears that primarily the crevice corrosion propagation results from a combined action of localised acidification and differential aeration between the bold and occluded zones. This mechanistic understanding provides further insights in to the development of crevice corrosion experienced by nickel-aluminium bronze after long-term exposures to natural seawater for up to 3 years.     

Corrosion of similar and dissimilar metal crevices in the engineered barrier system of a potential nuclear waste repository

Crevice corrosion is considered possible if the corrosion potential (E_corr) exceeds the repassivation potential for crevice corrosion (E_rcrev). In this study, potentiodynamic polarization and potentiostatic hold were used to determine the E_rcrev of similar and dissimilar metal crevices in the engineered barrier system of the potential Yucca Mountain repository in 0.5 M NaCl, 4 M NaCl, and 4 M MgCl₂ solutions at 95 °C. The results were compared with data previously obtained using crevices formed between Alloy 22 and polytetrafluoroethylene. It was observed that, except for Type 316L stainless steel, all other metal-to-metal crevices were less susceptible to crevice corrosion than the corresponding metal-to-polytetrafluoroethylene crevices. Measurements of galvanic coupling were used to evaluate the crevice corrosion propagation behavior in 5 M NaCl solution at 95 °C. The crevice specimens were coupled to either an Alloy 22 or a Titanium Grade 7 plate using metal or polytetrafluoroethylene crevice washers. Crevice corrosion of Type 316L stainless steel propagated without repassivation. For all the tests using a polytetrafluoroethylene crevice washer, crevice corrosion of Alloy 22 was initiated at open circuit potential by the addition of CuCl₂ as an oxidant, whereas no crevice corrosion of Alloy 22 was initiated for all the tests using Alloy 22 or Titanium Grade 7 metals as crevice washer. However, crevice corrosion propagation was found to be very limited under such test conditions.     

Initiation and propagation of pitting and crevice corrosion of hydrogen-containing passive films on X70 micro-alloyed steel

Hydrogen promoted initiation and propagation of pitting and crevice corrosion of X70 micro-alloyed steel were characterized by potential dynamic measurements, the scanning reference electrode technique (SRET) and electrochemical impedance spectra (EIS). At open circuit potential, in situ SRET results show that hydrogen accelerates the nucleation and propagation of pitting of X70 steel. The pitting potential E_p of X70 steel gradually decreases with an increase of chloride ion concentration in NaHCO₃ solution. Pre-charged hydrogen does not have a significant effect on the pitting potential E_p and open circuit potential E_corr of the steel in 0.5 M NaHCO₃ solution. However, a synergistic effect of hydrogen and Cl⁻ on the anodic dissolution and pitting potential of X70 steel is observed in 0.5 M NaHCO₃ solution containing chloride ions. When crevices are present in X70 steel, hydrogen accelerates the initiation and progress of crevice corrosion. The mechanisms by which hydrogen promotes the initiation and propagation of pitting and crevice corrosion are proposed and discussed.     

膨胀机主轴缝隙腐蚀的电化学分析

为探究膨胀机主轴的缝隙腐蚀行为,搭建了模拟缝隙腐蚀实验装置。通过电化学测试,确定了不同缝隙位置处的自腐蚀电位随时间的变化规律,并揭示了缝隙内腐蚀反应的发展过程。结果表明:缝隙内腐蚀反应经历双电层形成-氧浓差电池形成-金属水解三个反应过程。在富氧条件下,腐蚀产物的主要成分为Fe(OH)2。随着氧气的耗尽,氧浓差电池形成,腐蚀产物逐渐向FeOOH和Fe3O4转变。     

仿古铸铁的局部腐蚀和相转移研究

The corrosion behaviors of simulated archaeological iron in solution （0.06 mol·L^-1 NaCl＋0.03 mol·L^-1 Na2SO4＋0.01 mol·L^-1 NaHCO3） simulating soil water composition was investigated by potentialdynamic polarization, constant potential polarization, and simulated occluded cell （O.C.） galvanostatic tests. X-ray diffraction （XRD）, energy dispersive spectrometry （EDS）, and scanning electron microscope （SEM） were used to study the corrosion morphology and the evolution of corrosion product. The objective was to discover the transformation process of archaeological iron, and determine the distribution of chlorinated corrosion products. The results showed that the presence of crevice, cavities, and channels facilitates the localized corrosion under rusts; the autocatalytic effect increases the concentration of Fe^2＋, Cl^-, and SO4^2- , and promotes local acidification within the crevices and cavities. Meanwhile, the phase transformation of corrosion products is concluded to proceed by means of two ways. One is that the ferrous ions are transformed into different kinds of FeOOH via the intermediate Fe（Ⅱ）-Fe（Ⅲ） hydroxyl-salt （i.e. Green Rusts）; the other is that the Fe^2＋ ions are transformed into FeCl2, FeCl3, and orange powders akaganeite at the crevices and cavities.     

Pitting on the crevice wall prior to crevice corrosion: Iron in sulfate/chromate solution

Experimental results are presented for the induction period that precedes the onset of crevice corrosion. In situ visual examination and ex situ microscopy revealed that the first corrosive attack on the (passive) crevice wall occurs as a pit near the bottom of the crevice. Additional pits and corrosion product form higher and higher on the crevice wall during the induction period. The measured current is initially low in the passive range (10 μA), increasing gradually, but the measured current does not record the large increases in anodic current that produce the pits. The latter result and the observation that gas bubbles form within the pits indicate that the pitting initially is a local cell process of metal dissolution and cathodic reactions on the sample, including H₂ formation which occurs inside the pits in this iron/sulfate-chromate solution (pH 8.8, room temperature). Then, a transition from merging pits to corrosive attack across the width of the crevice wall occurs accompanied by a much steeper increasing current. This latter morphology (horizontal boundary that moves up the wall towards the crevice opening, heaviest attack just below this boundary and passive crevice wall above this boundary) is representative of stable crevice corrosion of the IR type reported in the literature.     

氯离子与冷却水系统中不锈钢的腐蚀

综述了有关氯离子对冷却水系统中不锈钢腐蚀研究的最新进展,涉及冷却水中氯离子引发不锈钢孔蚀、缝隙腐蚀和应力腐蚀开裂的机理,氯离子的限度,以及影响水中不锈钢腐蚀的其他因素.对如何应对冷却水中氯离子的负面效应提出了见解.