镁合金阳极氧化膜腐蚀过程的电化学阻抗谱研究

采用阳极氧化工艺对AZ91D镁合金进行表面处理，利用电化学阻抗谱（EIS）方法研究AZ91D镁合金阳极氧化膜层在3．5％NaCl溶液中的腐蚀过程。根据腐蚀过程阻抗谱的变化特点，分别采用R（RQ）（RQ）模型和R（Q（R（RQ）））模型的等效电路来拟合阳极氧化膜层在孔蚀诱导期和在孔蚀发展期的电化学阻抗谱图。结果表明：在孔蚀诱导期，随浸泡时间的延长，溶液电阻Rsol和多孔层的电容Yp有所增大，多孔层电阻琊和阻挡层电阻风逐渐减小，弥散效应指数np值基本不变，而阻挡层的电容Yb和弥散效应指数nb无明显的规律性；在孔蚀发展期，随浸泡时间的延长，溶液电阻Rsol，弥散效应指数n1和蚀孔内的反应电阻R2逐渐减小，电容Y1逐渐增大，而蚀孔内溶液电阻R1，蚀孔内阳极金属／介质界面的常相位角元件Q2的电容Y2及弥散效应指数n2无明显的规律性。     

7A04铝合金在海洋大气环境中初期腐蚀的电化学特性

通过盐雾腐蚀试验模拟研究7A04铝合金在海洋大气环境中的腐蚀初期规律,采用电化学交流阻抗测试和扫描Kelvin探针技术,研究7A04铝合金在初期腐蚀过程中的电化学行为.结果表明:Cl-对铝合金腐蚀有显著的加速作用,盐雾试验初期表面出现点蚀坑;随盐雾时间增长,点蚀相互连接并扩展,电化学反应阻抗下降.扫描开尔文探针测试结果表明:随腐蚀的不断进行,金属表面阴极区和阳极区不断发生变化,呈现局部腐蚀的特征,表面电位也随时间逐渐升高,阴极区和阳极区逐渐变得明显,腐蚀反应处于不断加速过程.     

NaCl薄液膜下不锈钢腐蚀行为研究

利用Kelvin探针参比电极技术和电化学阻抗方法研究了不锈钢在不同厚度NaCl薄液膜下的腐蚀行为.结果表明:在0.35%NaCl液膜厚度7～90 μm范围内,随着液层厚度的增大,不锈钢在薄液膜下腐蚀的氧扩散控制特征越显著,而且氧还原反应极限电流逐渐降低;3.5%NaCl薄液膜下阻抗测得的溶液电阻随着液膜增厚而首先迅速降低然后趋于平稳;在液层较厚时(425～120 μm)随着液层厚度的减小,腐蚀速度受氧扩散控制逐渐增大;液层厚度减薄至40～120 μm区间,由于阳极反应受抑制和阴极反应加速的共同影响腐蚀速度会出现极小值;液层厚度非常薄(20 μm以下)时由于电流分布不均匀抑制了氧还原,腐蚀速度很低.     

氧化时间对2A12铝合金阳极氧化膜开裂行为的影响

采用不同阳极氧化时间制备氧化膜,并采用扫描电镜、电子探针、连续性检测、交流阻抗法和盐雾腐蚀试验对阳极氧化膜进行了研究。结果表明,不同阳极氧化时间生成的氧化膜层经热冲击后都会出现非穿透性裂纹;随阳极氧化时间延长,经热冲击后,氧化膜层裂纹密度增大。综合考虑不同氧化时间下制备的氧化膜的开裂行为和耐蚀性变化,阳极氧化30 min制备的膜层在热冲击后具相对较好的防护性能。     

电化学法研究铝阳极氧化膜的抗腐蚀性

工业纯铝L2在硫酸溶液中进行阳极氧化制得阳极氧化膜,测试了此阳极氧化膜在NaCl溶液中的电化学性能。通过动态极化法和交流阻抗法对阳极氧化膜进行分析,发现阳极氧化膜的制备条件(电解液浓度、时间、电压等)不同时,膜的抗腐蚀性能也不同。电化学阻抗法测定表明,随浸泡时间的增加,膜阻抗值明显增大,可能是多孔膜在介质溶液中存在一个自然水合封闭的过程。     

钛钼合金电极在酸性介质中的电化学研究

采用交流阻抗和光电化学等测量方法研究了钛钼合金电极在0.2mol.L-1硫酸和0.2mol.L-1盐酸溶液中的电化学行为。交流阻抗测试结果表明,随着形成钝化膜的极化电位的增加,合金电极的阻抗增大,Mo在合金中的含量达到20%时,电极的阻抗模值|Z|0.05达到最大值;光电流循环伏安测量结果表明合金电极在阳极极化过程中显示阳极光电流,光电流iph随阳极极化电位增大而增加,表明电极表面膜呈n型半导体性质。     

NaCI薄液膜下不锈钢腐蚀行为研究

利用Kelvin探针参比电极技术和电化学阻抗方法研究了不锈钢在不同厚度NaCI薄液膜下的腐蚀行为．结果表明：在0．35％NaCl液膜厚度7～90μm范围内,随着液层厚度的增大,不锈钢在薄液膜下腐蚀的氧扩散控制特征越显著,而且氧还原反应极限电流逐渐降低;3．5％NaCI薄液膜下阻抗测得的溶液电阻随着液膜增厚而首先迅速降低然后趋于平稳;在液层较厚时（425～120μm）随着液层厚度的减小,腐蚀速度受氧扩散控制逐渐增大;液层厚度减薄至40～120μm区间,由于阳极反应受抑制和阴极反应加速的共同影响腐蚀速度会出现极小值;液层厚度非常薄（20μm以下）时由于电流分布不均匀抑制了氧还原,腐蚀速度很低．     

添加剂对电镀锌层烷氧基硅烷钝化膜电化学行为的影响

为提高镀锌层钝化膜的耐蚀性,利用极化曲线和交流阻抗谱,研究了不同添加剂对镀锌层烷氧基硅烷钝化膜腐蚀性能的影响.并与加速腐蚀试验结果进行了对比.试验结果表明,添加剂的加入明显改变了钝化膜层的腐蚀电位,提高钝化膜的交流阻抗值,烷氧基硅烷钝化膜的耐蚀性明显提高.     

铝阳极氧化膜在NaCl溶液中的电化学性能

采用交流阻抗法研究了工业纯铝L3阳极氧化膜在中性NaCl溶液中交流阻抗谱的变化规律, 比较了未封闭处理与沸水封闭处理后氧化膜的交流阻抗谱的差异, 并结合等效电路分析了氧化膜多孔层与阻挡层电化学参数的变化.结果表明, 未封闭的阳极氧化膜在NaCl溶液中浸泡初期存在一个自封闭过程, 封闭处理明显提高氧化膜多孔层的初始Rp值并降低初始CPEp值; 溶液中侵蚀性离子浓度越高, 封闭处理提高铝阳极氧化膜的耐蚀性能作用越明显.     

钼酸钠对钢筋在氯离子混凝土模拟液中腐蚀行为的影响

利用动电位极化曲线、交流阻抗技术及Mott-Schottky曲线等方法,研究了钼酸钠对钢筋在5%NaCl混凝土模拟液中的电化学腐蚀行为和表面钝化膜性能的影响.结果表明:随钼酸钠浓度增大,缓蚀效率逐渐增加,对钢筋的腐蚀有较好地抑制作用,药剂在钢筋表面的吸附可有效屏蔽氯离子的侵蚀作用;Mott-Schottky结果表明,在-0.5~0.1 VSCE范围内,混凝土模拟液中钢筋表面钝化膜Cs-c2-E曲线呈正线性相关,表明钢筋表面钝化膜为n型半导体,且随钼酸钠浓度增大,钢筋钝化膜载流子密度逐渐减小,钝化膜稳定性增强,耐蚀性逐步提高;钝化膜致密性分析表明,随钼酸钠浓度增大,钝化膜致密性增加,抗氯离子腐蚀能力增强.     

Environmental friendly plasma electrolytic oxidation of AM60 magnesium alloy and its corrosion resistance

Plasma electrolytic oxidation of Mg-based AM60 alloys was investigated using 50 Hz AC anodizing technique in an alkaline borate solution, which contained a new kind of organic. The anodic film is relatively smooth with some micro pores and cracks, while the anodic film consists of MgO, MgAl2O4 and MgSiO3. The electrochemical behavior of anodic film was studied by electrochemical impedance spectroscopy and potentiodynamic polarization. Polarization results indicate the PEO treatment can decrease corrosion current by 3-4 magnitude compared with blank AM60 alloy. The anodic film presents a good level of corrosion protection for AM60 magnesium alloy, over 272 h of the salt spray test based on ASTM B 117. The effect of micro-structure and composition on corrosion protection efficiency was also investigated.     

Influence of molybdate species on the tartaric acid/sulphuric acid anodic films grown on AA2024 T3 aerospace alloy

AA2024 T3 alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.     

EIS study of porous NiTi biomedical alloy in simulated body fluid

The electrochemical impedance spectroscopy was used for monitoring the formation of surface film on a fixtured sintering porous NiTi biomedical alloy in simulated body fluid (SBF) media during 12 days. Effect of NiTi sintering time on the formation of surface film in SBF was investigated. The formed surface film was calcium phosphate hydrate (CPH) with a pillar particulate structure which was developed to a spongy network with increasing the sintering time. Using such electrochemical techniques, it was shown that NiTi samples obtained after 3 h sintering at 950 °C, have higher tendency for the formation of a stable CPH film during the test.     

铝阳极氧化膜的微观结构及沸水封闭处理对膜层显微硬度的影响

通过阳极氧化在铝合金表面获得稳定的阳极氧化膜,并对膜层进行沸水封闭处理,采用扫描电子显微镜(SEM)、电化学阻抗谱(EIS)等分析手段研究了氧化电流密度以及封闭处理对膜层显微硬度的影响。结果表明:随着电流密度的增加,铝合金阳极氧化膜的显微硬度先升高,后降低;沸水封闭会导致铝阳极氧化膜的显微硬度下降;铝阳极氧化膜表面形貌的优劣、多孔层的组织结构和屏蔽性与膜层显微硬度密切相关。     

多孔NiTi合金直流-脉冲阳极氧化表面改性研究

采用低温直流-脉冲阳极氧化技术对多孔NiTi合金表面进行改性,分析直流-脉冲阳极氧化过程,利用XPS、SEM、动电位极化对阳极氧化膜的组成、形貌以及耐腐蚀性进行研究,观察阳极氧化前后多孔NiTi合金在模拟人工体液中Ni离子释放行为。研究结果表明在直流3 A、脉冲6 A下阳极氧化的多孔NiTi合金表面形成了一层均匀的多孔氧化膜,其厚度在190 nm左右,主要成分为Ti的氧化物,阳极氧化后多孔NiTi合金的耐腐蚀性显著提高,其Ni离子释放速率大幅度降低。     

A study on the self-sealing process of anodic films on aluminum by EIS

The electrochemical behaviors of anodized aluminum in neutral NaCl and Na₂SO₄ solutions were studied using electrochemical impedance spectroscopy (EIS). The results reveal that there is a self-sealing process for unsealed anodic film in neutral NaCl and Na₂SO₄ solutions. The resistance of the porous layer (R_p) and the capacitance of the barrier layer (CPE_b) increase and the capacitance of the porous layer (CPE_p) decreases with immersion time in the initial stage. Corrosion resistance provided by the anodic film is improved by the self-sealing process of the porous layer. However, chloride ions have an opposite effect. The improving effect of the self-sealing process on film resistance is decreased with the increase of chloride concentration of the solution.     

SP700 钛合金的热处理 / 阳极氧化工艺研究

目的采用电化学阳极氧化法,在SP700钛合金的表面制备多孔结构的氧化膜。方法利用Autolab PGSTAT30型电化学工作站,采用三电极体系,辅助阴极为石墨电极,参比电极为饱和甘汞电极,工作电极为试样,测定试样的动态极化曲线和阳极氧化I-t曲线。利用扫描电子显微镜观察阳极氧化表面多孔氧化膜的微观形貌,分析热处理工艺、阳极氧化电压、电解液成分等参数对SP700钛合金阳极氧化行为的影响规律。结果钛合金材料经固溶时效处理后,α相和β相的相对含量发生了变化,从而使氧离子对电化学反应界面的内应力发生变化,使得表层氧化膜更加平整,耐腐蚀性提高。F-是阳极氧化膜上纳米孔形成的必要条件,随着F-浓度的增加,阳极氧化膜表面纳米孔的密集程度增加,孔径减小,氧化膜厚度增加。在一定范围内,随着阳极氧化电压的增大,氧化膜增厚,但电压过高会破坏氧化膜的稳定性。结论用电化学阳极氧化法处理钛合金表面,得到了多孔结构的氧化膜,获得了理想的耐腐蚀性能。固溶时效处理后,钛合金的耐腐蚀性提高。     

硼酸对7050铝合金硼酸-硫酸阳极氧化膜结构及耐蚀性的影响(英文)

通过 AFM、交流阻抗谱及扫描 Kelvin 探针技术,研究硼酸对 7050 铝合金硼酸?硫酸阳极氧化膜结构及耐蚀性的影响。结果表明,在硼酸-硫酸阳极氧化体系中,硼酸不会改变氧化膜阻挡层的结构,但会显著影响氧化膜多孔层的结构形式,进而影响氧化膜的耐蚀性。在 0～8 g/L 的范围内,随着电解液中硼酸含量的增加,氧化膜的多孔层电阻增大,电容减小,表面势正移,孔径缩小,耐蚀性变好。在高于 8 g/L 时,随着硼酸含量的增加,氧化膜的孔隙变大,阻抗变小,电子逸出功降低,耐蚀性变差。     

非恒温电解液中AA5083Al-Mg合金阳极氧化膜的制备及其耐蚀性

采用硼酸-硫酸-草酸电解液在铝合金表面制备有序多孔层,研究阳极氧化过程中电流随时间的变化,分析界面反应并计算膜层的生长效率。采用扫描电子显微镜、交流阻抗和动电位极化曲线研究膜层的微结构及其在不同温度环境下的耐蚀性。结果表明：在氧化层界面双离子层浓度的增大有利于提高膜层的生长效率。所制备的阳极氧化膜厚度为8-9μm,孔径为10-14 nm,膜层的微观形貌受金属基体组织结构的影响较大。在沸水封闭后膜层为分层结构,表面呈细片状。氧化膜层封闭后能够明显降低试样的自腐蚀电流密度,且耐蚀性随着环境温度的升高而具有更好的稳定性。     

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.