CHARACTERISTICS AND FORMATION MECHANISM OF CORROSION SCALES ON LOW--CHROMIUM X65 STEELS IN CO2 ENVIRONMENT

利用高温高压CO₂腐蚀模拟实验以及ESEM, EDS, XPS和SEM等分析技术, 研究了4种不同含Cr量的X65管线钢的腐蚀速率、腐蚀形态和腐蚀产物膜结构特征. 结果表明: 含Cr量高的钢平均腐蚀速率小, 无Cr和含1\%Cr的钢的腐蚀形态为局部腐蚀, 含3%和5%Cr的钢的腐蚀形态为全面腐蚀. 在高温高压CO₂腐蚀环境中, 含Cr钢的腐蚀产物膜为FeCO₃和Cr(OH)₃竞争沉积形成的多层结构, 其中1Cr-X65和3Cr-X65的腐蚀膜具有3层结构, 5Cr-X65的腐蚀膜是双层结构. Cr在腐蚀产物膜层中出现局部富集, 远高于基体中的Cr含量. 高含Cr量使腐蚀产物膜中的Cr(OH)₃含量高, 并提高了腐蚀膜的保护性能, 从而引起腐蚀形态发生转变, 腐蚀速率降低. FeCO₃和Cr(OH)₃共沉积层膜对低铬钢的抗CO₂腐蚀性能具有关键的影响.     

温度和硫离子对N80钢CO2腐蚀电化学行为影响

应用电化学阻抗谱、EIS扫描电镜(SEM)及能谱（EDS）研究了温度和硫离子交互作用下,N80钢的CO₂腐蚀电化学行为及腐蚀膜的形貌与组成.结果表明：温度和硫离子对N80钢CO₂腐蚀电化学行为影响显著;硫离子加入后试样表面吸附着一层腐蚀膜;随着油田地层水中S^2-浓度的增加,传递电阻R₁、膜电阻R₂及扩散阻抗W增加,膜电容Q₂减小;腐蚀膜主要由FeS及少量FeCO₃组成;其致密性随硫离子含量增加和温度升高而增强.               

N80钢在二氧化碳饱和的模拟油田液中的高温高压腐蚀行为研究

        用失重法研究了高温高压下N80钢在模拟油田液中的腐蚀行为.结果表明： 随着温度及CO₂分压的升高,N80钢的腐蚀速率增大,并在5 MPa及100℃时达到最大值.在此基础上,考察了Cl^-对腐蚀速率的影响.     

温度对N80钢在饱和CO2模拟地层水下腐蚀行为的影响及机理

目的 研究N80钢在饱和CO2模拟油田地层水中于不同温度下的腐蚀行为及腐蚀特征,探究N80钢在饱和CO2模拟油田地层水中的腐蚀规律及机理。方法 利用高温高压釜对N80钢在不同温度(60、90、120 ℃)的饱和CO2模拟油田地层水中浸泡96 h的失重腐蚀进行测试,并用电化学分析仪对其进行相同条件下的宏观电化学测试。采用XRD、SEM、EDS对N80钢腐蚀后的腐蚀产物物相结构、表面形貌、元素组成及腐蚀产物去除后基体表面的腐蚀形貌进行分析。结果 N80钢在饱和CO2模拟油田地层水中所形成的腐蚀产物主要由FeCO3和溶液介质中的结晶盐CaCO3组成。温度影响腐蚀产物膜的形貌特征、晶粒尺寸及其致密度变化,导致基体发生不同程度的腐蚀。60 ℃时,表面生成的腐蚀产物膜均匀覆盖于基体表面,产物膜膜层平整、致密,去除腐蚀产物后,表面有少量点蚀坑;温度升至90 ℃时,基体表面覆盖的腐蚀产物凹凸不平,晶粒粗大,排列较乱,规则性差于60 ℃下的腐蚀产物,腐蚀产物去除后,发现基体表面有大片蚀坑群,发生连片腐蚀;120 ℃时,腐蚀产物晶粒减少,覆盖不均,具有明显蚀孔和裂纹,部分腐蚀产物脱落,去除腐蚀产物后的基体表面出现大面积蚀坑,发生严重腐蚀。N80钢的腐蚀速率由60 ℃时的0.021 0 g/(m².h)增至90 ℃时的0.036 0 g/(m².h),至120 ℃时的0.044 4 g/(m².h)。N80钢的自腐蚀电流密度由60 ℃时的1.362 3× 10^?6 A/cm²增至90 ℃时的1.427 3×10^?6 A/cm²,至120 ℃时的1.785 1×10^?6 A/cm²,但其自腐蚀电位则随温度的增加而减小。结论 随腐蚀温度增加,N80钢表面所生成的腐蚀产物膜变得较疏松,且膜层含较多微孔与裂纹,腐蚀速率持续增加,N80钢腐蚀加重。     

注多元热流体环境下流速对N80钢腐蚀行为的影响研究

目的 研究不同流速条件下N80钢在注多元热流体环境中的腐蚀特征,探究流速变化对N80钢腐蚀行为的影响规律及机理。方法 利用自制高温高压多相流冲刷腐蚀环路装置模拟不同流速(0、0.5、1.0、2.0 m/s)的注多元热流体环境,采用失重法计算不同流速下N80钢的平均腐蚀速率,并同时进行原位电化学测试。采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对不同流速条件下N80钢腐蚀后的腐蚀产物物相组成和表面微观形貌进行分析。结果 N80钢在注多元热流体环境中的平均腐蚀速率随着流速增加而增大。流速增加影响O2的扩散传质过程、近表面离子分布和壁面剪切力的大小,使腐蚀产物膜特征发生变化。0 m/s时,腐蚀产物主要由FeCO3和少量Fe2O3组成,为单层膜结构,腐蚀形态为均匀腐蚀。0.5~2.0 m/s范围内,腐蚀产物种类增加,主要由FeCO3、Fe2O3和少量FeO(OH)组成,呈双层膜结构,同时N80钢表面腐蚀产物膜出现鼓泡,且随流速增加鼓泡数量增加,去除腐蚀产物膜后发现鼓泡下方存在局部腐蚀。原位电化学测试结果表明:随着流速增加,塔菲尔极化曲线的阳极斜率增大,阴极斜率减小。电化学阻抗谱测试结果表明,N80钢表面外层腐蚀产物膜电阻Rf1、电荷转移电阻Rct和扩散电阻W随流速增加而减小。结论 流速增大加快了O2的扩散传质过程,使得腐蚀电化学控制步骤由阴极氧扩散过程转变为阳极溶解过程,且试样表面保护性FeCO3膜厚度减小,导致产物膜保护性降低。另外,Fe²⁺更容易被氧化形成Fe³⁺,局部FeCO3被氧化成为Fe2O3,破坏了内层膜的完整性,导致局部腐蚀发生。     

Fe-14Cr-Mn合金在不同温度熔融共晶NaCl-MgCl2中腐蚀行为及机理研究

熔融共晶NaCl-MgCl₂作为太阳能中高温相变储热介质,运行状态下其温度常在熔点附近波动。但不同温度下该熔融盐对金属容器材料腐蚀行为不清楚。以Fe-14Cr-Mn合金为例,采用浸盐法研究了718K、768K和818K熔融共晶NaCl-MgCl₂对该合金的腐蚀行为,探讨了腐蚀机理。结果表明：腐蚀速率随温度增加略微增加,三种温度下试样腐蚀动力学曲线服从线性规律(斜率约k=-4.806E-4)。腐蚀初期,试样表面形成泡状腐蚀产物,腐蚀80h后形成腐蚀坑洞,主要是Fe、Fe-Cr和MgO,也检测到含微量Fe和Ni的Mg-Fe-Ni的氧化物。腐蚀机理主要是MgCl₂吸潮后以H₂O形式引入的氧原子和溶解在熔融盐中的微量氧作为阴极去极化剂,合金元素Cr和Mn与Cl_-反应生成的氯化物,氯化物吸附水分子,形成具有低熔点的含水氯化物(如CrCl₃.6 (H₂O) 和MnCl₂.n (H₂O))逃逸腐蚀体系。另外,在熔岩表面形成了由MgCl₂. (H₂O) ₆, NaCl 和 MgO组成的盐壳,而在熔融盐内部,NaCl与NaMgCl₃共存。本研究为研发耐熔融NaCl-MgCl₂腐蚀的新合金奠定了基础。     

紫铜在云南热带雨林土壤中的长期腐蚀行为

本文采用失重法、形貌分析、成分分析和电化学测试等方法研究了紫铜管长期埋藏于热带雨林土壤环境中的腐蚀行为。结果表面,紫铜管埋藏16年后,平均腐蚀速率为2.5μm/y,腐蚀失重规律符合幂函数模型,其拟合方程为C=0.4273t_-0.246^{。紫铜管表面腐蚀产物呈淡绿色的致密鳞状结构},与金属基体结合良好。 XPS、EDS和FTIR分析结果显示该腐蚀产物主要成分为铜绿(Cu₂(OH)₂CO₃)。电化学测试结果表明,埋藏16年后,紫铜管腐蚀速率变小,阻抗值明显增大,表明腐蚀产物膜对基体形成良好的保护作用,能有效减缓腐蚀过程的继续发展。     

Cu、Ni元素对耐蚀高锰阻尼钢在大气环境中腐蚀行为的影响

高锰阻尼钢因其高强度、超低屈强比、阻尼性能良好和经济性能优异等特性,在承受较大振动和冲击的桥梁、轨道交通和军工等领域展现出广阔的应用前景。而高锰钢耐蚀性能欠佳一直是限制其快速发展的关键性因素,高锰钢耐蚀性设计及其大气腐蚀行为研究均鲜有报道。为解决高锰钢耐蚀性能欠佳问题,采用真空感应熔炼和两阶段轧制工艺制备 3 种添加不同 Cu、Ni 元素含量的耐蚀高锰阻尼钢,通过大气曝晒试验、电化学测试、SEM、XRD 和 XPS 等方法对试验材料的电化学性能、 腐蚀速率、腐蚀形貌、腐蚀产物物相及结构进行表征及分析。结果表明：相较于单独添加 Cu 元素的高锰阻尼钢,钢中添加 1.2 wt.% Cu 和 1.0 wt.% Ni 元素腐蚀电位正移近 200 mV,腐蚀电流密度降低近 50%;曝晒试验后,较高含量的 Cu 和 Ni 元素协同添加使腐蚀产物中 α-FeOOH 含量明显提高,活性较高的 MnFe₂O₄和 Mn₂O₃含量降低,耐蚀产物 NiOOH 及 CuO 含量增加。腐蚀产物颗粒均匀细小,产物层整体致密光滑,保护性能提高,其腐蚀速率相较于单独添加 Cu 元素的高锰阻尼钢降低 70%,表现出优异的耐蚀性能。所提出的高锰阻尼钢耐蚀性的成分设计方案及耐蚀机理可为未来高锰阻尼钢在桥梁中的应用提供数据支持。     

二氧化碳驱注采井常用油套管钢的腐蚀行为

采用高温高压反应釜研究了N80、P110、3Cr、5Cr等4种油套管钢材在现场采出液中的抗CO_2腐蚀性能,结合扫描电镜(SEM)、能谱仪(EDS)和X射线衍射(XRD)等手段,观察分析了腐蚀产物膜形貌和成分。结果表明:随着温度的上升,4种钢材腐蚀速率均呈现出先增大后减小的趋势,最大值出现在中温区,N80、P110、5Cr钢在90℃时腐蚀速率达到最大,3Cr钢在80℃时腐蚀速率最大;4种钢材腐蚀类型主要为均匀腐蚀,未发现局部腐蚀,腐蚀产物主要为FeCO_3,含Cr钢腐蚀产物出现多层结构,主要成分除了FeCO_3,还有非晶态的腐蚀产物Cr(OH)_3;N80、P110钢的腐蚀产物细小、致密、均匀覆盖在基体表面,腐蚀速率较低;3Cr、5Cr钢的腐蚀产物覆盖不均匀、与基体结合力弱、附着性不强,易脱落,造成整体腐蚀速率较高。     

在Q235钢表面原位生长的氧化铁膜对其在含Cl-溶液中腐蚀行为的影响Ⅰ-原位生长的γ-FeOOH膜的防护性能

    利用动电位极化曲线和交流阻抗谱等电化学测量技术,研究了Q235钢表面原位生长的γ- FeOOH膜在0.25 mol/L Na₂SO₄+10^-4mol/L NaCl、0.25 mol/L Na₂SO₄+10-3mol/L NaCl、0.25 mol/L Na₂SO₄+10^-2 mol/L NaCl水溶液中的电化学行为及在不同浓度的Cl^-水溶液中γ-FeOOH膜对Q235钢的保护作用.结果表明,Cl^-含量较低时,γ-FeOOH膜的存在明显地促进了Q235钢的阴极反应,该膜对基材无保护作用;随Cl-浓度的增加,阴极电流密度大幅减小,当Cl^-浓度达到10^-2 mol/L时,γ-FeOOH 膜能在一定程度上抑制基材的腐蚀,此时γ-FeOOH膜表现出对基材有保护作用.     

pH 值对 N80 钢固液两相冲刷腐蚀的影响

在加入10%石英砂的3.5%NaCl溶液中,对N80钢进行了冲刷腐蚀试验。通过失重法计算了腐蚀速率,观察了宏观、微观腐蚀形貌,对腐蚀后的表面进行了EDS分析,据此研究了pH值对冲刷腐蚀的影响和冲刷腐蚀机理。结果表明:随着pH值的升高,N80钢的冲刷腐蚀速率降低;pH较低(2或3)时,为均匀腐蚀,pH值升高后,出现了氧化。     

Effect of calcium ions on pitting corrosion and inhibition performance in CO2 corrosion of N80 steel

The electrochemical impedance spectroscopy (EIS) and polarization resistance technique were used to investigate the susceptibility of N80 steel to pitting corrosion under stagnant condition and the corrosion behavior under flowing condition with/without precorrosion in 3% NaCl solution, in 3% NaCl + 1.5% CaCl₂ solution and in 4.6% NaCl solution (equivalent Cl⁻ concentration to 3% NaCl + 1.5% CaCl₂ solution) saturated by CO₂ at 57 °C. The results showed that under stagnant condition the initiation period of pitting corrosion decreased with increasing Cl⁻ concentration, but at the same Cl⁻ concentration, Ca²⁺ could prolong the initiation period. Under flowing condition the corrosion rate without stagnant precorrosion was bigger than that with precorrosion, and the corrosion rate with precorrosion in 3% NaCl solution was bigger than that in 3% NaCl + 1.5% CaCl₂ solution. Inhibition of quaternary alkynoxymethyl amine (IMC-80-Q) under stagnant condition showed that the optimum inhibitor concentration significantly increased with the increase of Cl⁻ concentration from 3% NaCl solution to 4.6% NaCl solution, and for the solutions with the same Cl⁻ concentration, adding Ca²⁺ did not change the optimum inhibitor concentration.     

Role of polyacrylamide concentration on corrosion behavior of N80 steel in the HPAM/H2S/CO2 environment

The effect of polyacrylamide on corrosion behavior of N80 steel in the HPAM/H₂S/CO₂ environment was studied by using weight-loss and electrochemical tests to simulate the environment of production wells in polymer flooding. The morphology and composition of corrosion scales were studied by scanning electron microscopy, energy dispersive X-ray spectrometer, and X-ray photoelectron spectroscopy. The results show that as the polyacrylamide concentration increases, the uniform corrosion rate of N80 steel decreases gradually. The safe service life of N80 steel grows along with the increase of the concentration of polyacrylamide. The corrosion scales of N80 steel in the HPAM/H₂S/CO₂ environment is split into two layers, an inner layer of O-rich composed of FeCO₃ and an outer layer of S-rich consisting of FeS. Polyacrylamide adsorbs on the surface of N80 steel to form a protective network, which blocks contact between the metal and the solution and then inhibits the anodic dissolution of the metal. Moreover, the growth of polyacrylamide concentration increases the pH value of the solution and promotes the ionization of H₂S, HS⁻, and H₂CO₃ in the solution.     

Corrosion of N80 carbon steel in oil field formation water containing CO2 in the absence and presence of acetic acid

Corrosion behaviour of N80 carbon steel in formation water containing CO₂ was studied by polarization curve technique, electrochemical impedance spectroscopy, weight loss test, scanning electron microscope, and X-ray diffraction. Effects of temperature and acetic acid concentration on the corrosion behaviour of N80 carbon steel were discussed. The results showed that increasing temperature not only enhanced the dissolution of steel substrate, but also promoted the precipitation of FeCO₃, the addition of acetic acid enhanced localized corrosion attack on N80 carbon steel. FeCO₃ was the main corrosion product. And there was a transition region between CO₂ corrosion control and HAc corrosion control.     

Studies on waterline corrosion processes and corrosion product characteristics of carbon steel in 3.5 wt% NaCl solution

The waterline corrosion behaviors of carbon steel partially immersed in a 3.5 wt% NaCl solution were investigated using the wire beam electrode technique, and the effects of corrosion products on the processes of waterline corrosion were analyzed. The results demonstrated that the initial stage and development stage of waterline corrosion were mainly controlled by the concentration and diffusion of dissolved oxygen, respectively, and the deceleration stage of waterline corrosion was mainly affected by corrosion products. The main component of the yellow corrosion products was γ-FeOOH, and γ-FeOOH that exhibited a high reduction reactivity could be involved in the cathodic reaction. The black corrosion products were mainly composed of Fe₃O₄ with strong thermodynamic stability and the processes of dissolved oxygen diffusion and ion transports were obviously affected due to the continuous accumulation of Fe₃O₄ on the surface of the electrodes. Polarity reversals were observed on the single electrodes below the waterline, but the reasons for the phenomena were different from each other.     

Study of the pitting corrosion of superduplex stainless steel and X-65 carbon steel during erosion–corrosion by cyclic polarisation technique

Erosion-enhanced corrosion behaviour of X-65 carbon steel and UNS S32750 superduplex stainless steel was investigated by electrochemical cyclic polarisation. The tests were performed using a jet slurry device coupled with a potentio-galvanostat at various jet velocities of 4, 6.5 and 9?m?s^?1 and impingement angles of 30 and 90? in a 3.5?wt-% NaCl water containing 6?wt-% silica sand particles. The results showed that increasing the jet velocity and impingement angle increased the corrosion rate of both alloys. Negative hysteresis and greater E_rp than OCP were observed for superduplex stainless steel in all erosion–corrosion conditions that indicated the pitting resistance of the alloy. However, the low resistance of carbon steel against pitting during erosion–corrosion was demonstrated by positive hysteresis in the cyclic polarisation curves as well as SEM images of the eroded surfaces.     

油套管N80钢的乙酸腐蚀行为

模拟油气田环境,采用高温高压釜对油套管N80钢进行失重腐蚀试验.结果表明:N80钢的腐蚀速率随着乙酸浓度的增加呈升高趋势,但在乙酸浓度为3000μl/L时反而比在1000μl/L时低,并且其在含乙酸的腐蚀介质中的腐蚀速率远高于在未含乙酸的腐蚀介质中的腐蚀速率.利用扫描电子显微镜(SEM)、能散X射线谱仪(EDS)和X射线衍射技术(XRD)研究了在不同乙酸浓度条件下油管钢N80腐蚀的特征并讨论了其腐蚀机理.     

电力铁塔角钢镀锌层在NaCl介质中的腐蚀行为研究

采用Tafel直线外推法、加速腐蚀试验,研究了角钢镀锌层在NaCl溶液中的腐蚀行为,利用SEM和XRD表征角钢镀锌层的腐蚀形貌及腐蚀产物.结果表明:随着NaCl溶液温度和浓度升高,角钢镀锌层腐蚀电流密度增大;加速腐蚀试验的产物可阻碍Cl-腐蚀,使得角钢锌层的腐蚀速率随试验时间的延长而减小;锌层的氧浓差腐蚀为慢腐蚀过程,...     

Effects of NaCl,SO2, NH3, O3, and ultraviolet light on atmospheric corrosion of Zn

The atmospheric corrosion behavior of Zn was studied in laboratory environments containing constituents that have not previously received much attention, in particular, humidity, SO₂, NH ₃, and O ₃, along with ultraviolet (UV) light irradiation and a preloading of NaCl. After exposure, corrosion rates were measured using mass loss, and corrosion products were identified by X-ray diffraction, Fourier transform-infrared spectroscopy, and energy dispersive spectroscopy. In this study, UV light and O ₃ did not significantly affect the Zn corrosion rate in the absence of Cl ⁻. However, when NaCl was present, UV light inhibited the Zn corrosion rate below 90% relative humidity (RH) and accelerated the Zn corrosion rate at 99% RH. The presence of UV light also increased the formation of zinc hydroxyl sulfate and gordaite when exposed to 120 parts per billion (ppb) SO ₂ and NaCl. The combination of SO ₂ and O ₃ with the preloading of NaCl increased the corrosion rate of Zn compared with NaCl alone. NH ₃ at a concentration of 550 ppb did not have a significant effect on the Zn corrosion rate.     

双相钢在流动3.5aCl溶液中的磨损腐蚀

研究了０Ｃｒ２５Ｎｉ６Ｍｏ３Ｃｕ双相钢在流动３．５ＮａＣｌ溶液中的磨损腐蚀行为,并对其磨损腐蚀的动力学过程进行了探讨。结果发现;双相钢在流动３．５％ＮａＣｌ溶液中的磨损腐蚀速度随着流速的增大而增大,并存在一个使磨损座 刀剧上升的临界值,随阒温度的升高,其磨损腐蚀明显加重。