Development of pitting corrosion on 20Kh13 steel

The nucleation and propagation of corrosion pits on 20Kh13 steel in the NaCl solutions with various concentrations, temperatures, and pH values are studied under the potentiostatic conditions and at the free-corrosion potential. In the potentiostatic experiments, the variations of the depth and diameter of pits and their number with the time are determined. It is shown that the state of metal surface in a certain area adjacent to the active pits changes. The dimensions of the area are estimated. The results, which were obtained at the free-corrosion potential, were much less reproducible. At the free-corrosion potential, in contrast to the potentiostatic conditions, the pit depth increased only slightly and the pit width increased to a larger extent. It is shown that the pH value of NaCl solutions has a pronounced effect on the development of pitting corrosion on 20Kh13 steel.     

Pitting on the 20Kh13 steel in chloride solutions

The dependences of the pitting potential, determined by potentiodynamic method, on the NaCl solution concentration, pH, and temperature are found. The repassivation potential and the induction time for the pitting under different conditions are determined. The corrosion potential and kinetic parameters of the steel dissolution in pits are measured. The corrosion current is evaluated, leading to the determination of the steel dissolution rate in pits at the corrosion potential.     

Electrochemical behavior of stainless steel in aerated NaCl solutions by electrochemical impedance and rotating disk electrode methods

Electrochemical behavior of stainless steel in 0.5 M NaCl solutions is studied. It is shown that, for this steel, under a considerable cathodic polarization of electrode, the oxygen electroreduction proceeds via a four-electron mechanism. The corrosion current is estimated. From the impedance spectra, elements of an equivalent circuit that describes the electrode behavior under the ac conditions are calculated. A mechanism of the steel passivation in the electrolyte is proposed.     

混凝土中钢筋的腐蚀行为研究

本文探讨了在不同 pH和Cl- 含量的模拟混凝土孔隙液介质中 ,混凝土中钢筋的腐蚀电化学行为 .电化学技术测试结果表明 ,正常情况下 ,钢筋在混凝土中受到高碱性环境的保护 ,耐蚀性好 .但随着介质 pH的降低、Cl- 含量的上升 ,钢筋腐蚀电流升高 ;动电位阳极极化曲线的测试表明 ,钢筋的维钝电流增大 ,击穿电位负移 ,混凝土中钢筋的耐蚀性下降 .这是钢筋表面钝性受破坏的缘故 .     

铝阳极氧化膜在中性NaCl溶液中的亚稳态点蚀研究

使用动电位极化法,电化学噪声和扫描电镜技术研究了工业纯铝L2经不同电流密度阳极氧化和不同方法封闭后于1mol/LNaCl中性溶液中的腐蚀行为.结果表明,阳极氧化能大大提高L2的耐蚀性,但当氧化膜较薄或氧化膜经长时间在溶液中浸泡后,试样表面仍能发生亚稳态点蚀,并在极化曲线上出现电流振荡和电位振荡.扫描电镜观察则表明,这些亚稳态点蚀孔径一般小于10μm,主要产生在膜中的金属间化合物周围.若氧化膜厚度增加或使用沸水和重铬酸盐封闭,均可有效地抑制亚稳态点蚀的发生.     

Magnetic field effect on stainless steel corrosion in FeCl3 solution

Corrosion of AISI 303 stainless steel in FeCl₃ solution was studied in the magnetic field, whose direction was perpendicular to the corroding surface. The magnetic field inhibited corrosion in both quiet and stirred solutions. This was evident from the increased repassivation potential, the reduced number of pits and the decreased mass loss. By contrast, an accelerating effect of the magnetic field was observed on the single cathodic reaction of the corrosion process, viz. Fe(III) reduction to Fe(II). This was confirmed by voltammetric measurements on both platinum and stainless steel electrodes. The corrosion magnetoinhibition was explained in terms of field-assisted development of a passive layer, whose passivation capacity was higher than that under the field-free conditions.     

碳钢在NaNO_2-NaCl溶液中的电流波动

用动电位和恒电位极化法研究了A3碳钢在NaNO2＿NaCl溶液体系中的电流波动特征.A3钢在不含Cl-的0.1mol/LNaNO2溶液中能保持良好的钝态,当加入一定浓度的Cl-后,电流出现了明显的快速上升,再缓慢下降的波动特征,表明此时碳钢表面生成了溶解较快而再钝化相对较慢的亚稳态孔蚀.实验中可观察到因电流波动而产生的累积腐蚀损伤的蚀孔.实验表明,随着Cl-浓度的增加,出现亚稳态孔蚀的初始电位Em降低,相应的电流波动峰值增大,峰频增加;而升高电位,则电流波动的峰值和峰频也都增加,况且再钝化时间延长,由此可见电位的升高促进了亚稳态孔的溶解,并能激活更多的活性点使孔诱发速率增大.     

钙处理对桥梁钢耐大气腐蚀性能的影响

以NaCl+NaHSO₃溶液为腐蚀介质,采用干/湿周浸加速腐蚀实验、失重分析、XRD、SEM和电化学方法,研究了钙(Ca)处理对桥梁钢在湿热工业-海洋大气中腐蚀行为的影响. 结果表明：Ca处理前后,实验钢的腐蚀深度随时间变化曲线总体符合幂函数W=Atn分布规律,锈层主要由非晶物质和少量晶体α-FeOOH、β-FeOOH、γ-FeOOH、Fe₃O₄组成. 微量Ca能促进铁素体生成、强化钢表面保护膜,以阻止裸钢的快速腐蚀;还能细化钢组织晶粒、抑制腐蚀产物的晶体转变,以细化锈层颗粒、减少锈层缺陷产生,进而改善锈层的致密性.     

EIS study on the corrosion performance of a Cr(III)-based conversion coating on zinc galvanized steel for the automotive industry

The corrosion performance of a new industrial Cr(III)-based conversion coating on zinc galvanized FeP04 steel for the automotive industry was studied. For comparison, the zinc galvanized steel submitted to a Cr(VI)-based passivation treatment was also examined. The corrosion behavior was assessed by means of potentiodynamic polarization and electrochemical impedance spectroscopy measurements in aerated 0.1 M NaCl solution. The behavior of untreated zinc galvanized FeP04 steel in aerated 0.1 M NaCl solution was also studied. The results obtained indicate that with the same thickness, the coating generated in the Cr(III) treatment bath exhibits better corrosion properties compared to the coating formed in the Cr(VI) treatment bath. The difference in the corrosion protection given by the two conversion coating types can be ascribed to the difference in the chromium content and coating composition.     

镀锌扁钢电力接地材料在NaCl介质中的腐蚀特性

应用极化曲线、电化学阻抗谱和中性盐雾腐蚀试验法,研究电力接地材料镀锌扁钢在5%NaCl溶液中的腐蚀行为,扫描电子显微镜（SEM）、X射线衍射仪（XRD）观察与表征镀锌扁钢样品腐蚀的表面形貌及其产物性质.结果表明,在20～60℃温度范围内,镀锌扁钢腐蚀电流随温度升高而增大,60℃时腐蚀速率达到0.8408mA.cm-2（...     

Effect of inhibitors on corrosion resistance of carbon steel in suspensed liquid combined fertilizer

Inhibitors against corrosion of metal surfaces in salt solutions, especially of carbon steel in reference 5% NaCl solution and in suspension fertilizer were selected. We examined a corrosion kinetics, effect of corrosion protection, and also a penetration and a corrosion depth in the presence of various inhibitors.     

Formation of artificial micro‐pits on Al alloy with the photon rupture method and the localized corrosion behavior of the formed pits

An in situ artificial micro‐pit fabrication method with an area selective electrochemical measurement technique was applied to investigate the effect of the geometry of artificially formed pits on their localized corrosion behavior in anodized 1000 series aluminum. This technique enables the fabrication of artificial micro‐pits with different aspect ratios (pit depth/pit diameter) in solutions. The aspect ratios of the fabricated artificial micro‐pits in this experiment could be varied from 0.13 to 1.83 by controlling the irradiation time of the focused pulsed YAG laser beam. By applying a constant potential to the final laser‐beam‐irradiated spot in chloride environments, localized dissolution occurred only at the laser beam irradiated area, because the anodic oxide film acted as an insulator. The corrosion current and charge increase with increasing aspect ratio at any applied potential. Copyright © 2010 John Wiley & Sons, Ltd.     

深海静水压力环境下低合金高强度钢腐蚀行为研究

通过自行设计的深海环境模拟装置,采用静态挂片失重、动电位极化曲线及电化学阻抗谱（EIS）等方法系统研究了深海静水压力环境下低合金高强度钢（HSLA钢）在3.5% NaCl溶液中的腐蚀行为,并与常压下的结果对比,探讨了静水压力下HSLA钢在深海环境中的腐蚀行为. 结果显示,静水压力并没有改变HSLA钢在3.5% NaCl溶液中的腐蚀历程,不甚影响其阴极过程,而主要提高了其阳极腐蚀速率,这可能与高静水压下Cl-活性的增加有关.     

苯并三唑对水泥砂浆中钢筋的阻锈作用

应用腐蚀电位(E_corr)、极化电阻(R_p)和砂浆保护层电阻率(ρ_c)研究了苯并三唑(BTA)对钢筋电极腐蚀电化学行为的影响. 通过电化学阻抗谱(EIS)、循环极化(CP)和循环伏安(CV)结果对比了BTA与NaNO₂ (SN)对钢筋电极在未处理、预锈蚀和内掺氯盐3种状态下3.5% (w)氯盐浸泡360 d后的阻锈效率. 利用环境扫描电镜(ESEM)与能谱分析(EDS)解释了BTA对水泥基材料中钢筋的阻锈机理. 结果表明: 3种状态下BTA均能明显降低砂浆中钢筋的均匀腐蚀速率, 且其阻锈效率高于SN. 在未处理与预锈状态下, BTA抑制点蚀的能力稍弱于SN; 但在内掺氯盐的状态下, BTA表现出了较大的点蚀阻力. BTA除了能在钢筋表面形成复杂的保护膜, 从而有效抑制氯盐的破钝化作用. ESEM/EDS结果表明BTA还能与砂浆基体形成较多富钙C-S-H凝胶, 可能优化了钢筋/砂浆界面区的孔结构, 形成更致密的微观结构, 显著延缓了氯盐向钢筋表面的传输进程, 较好地保护了钢筋. 适量的BTA对砂浆360 d的基本力学性能无明显影响.     

A zirconia-polyester glycol coating on differently pretreated AISI 316L stainless steel: corrosion behavior in chloride solution

The effect of zirconia and zirconia-polyester glycol hybrid coatings on the corrosion resistance of mechanically polished or anodized AISI 316 stainless steel (316L), was studied by potentiodynamic polarization and electrochemical impedance spectroscopy in 0.1 M NaCl and scanning electron microscope and atomic force microscopy examinations. The deposition of zirconia coatings was achieved by the sol–gel technique by immersing the samples in either the inorganic polymer or the organic–inorganic polymer mixture. From potentiodynamic and impedance measurements, the grade of protection is reduced with the exposure time to the electrolyte, which is mainly associated with lost of film adhesion and, consequently, detachment from the metal substrate. However, the uncoated anodized sample revealed an unexpected corrosion behavior; the anodic film formed during anodizing readily increased the corrosion resistance of the 316L stainless steel in 0.1 M NaCl, revealing a considerable reduction in the corrosion current density and an increase in the pitting potential.     

Structural and electrochemical characterization of sputter-deposited nitrided NiCr alloys

Nickel-based coatings are potential candidates for the protection of electrochemical dissolution of steel surfaces. Such coatings, elaborated by magnetron sputtering in a nitrogen atmosphere, offer good corrosion protection, good adherence as well as stability for metallic structures. NiCr alloys with almost constant composition have been deposited with different nitrogen contents on stainless steel and carbon steel surfaces. The coating uniformity, homogeneity, composition and crystallinity have been studied by scanning electron microscopy, energy-dispersive X-ray spectrometry, atomic force microscopy and X-ray diffraction techniques. The corrosion degradation behavior of all the samples was tested in NaCl and NaCl and CO₂ mixture exposures using electrochemical impedance spectroscopy measurements. Nitrided NiCr alloys on a stainless steel substrate resulted with better adhesion than carbon steel, by delaying the corrosion mechanism when exposed to NaCl and CO₂ solution. A comparison of the corrosion resistive behavior of the substrates (stainless steel, carbon steel) and the coatings is made by using the electrical capacitance concept from a double-layer model for the coating–metal interface.     

模拟混凝土孔隙液中D-葡萄糖酸钠复合缓蚀剂对钢筋的阻锈作用

应用电化学技术, 结合扫描电子显微镜(SEM)观测, 研究D-葡萄糖酸钠、钼酸钠和硫脲三组分复合缓蚀剂对模拟混凝土孔隙液中钢筋腐蚀行为的影响及其阻锈作用. 结果表明: 在含3.5% (w) NaCl的模拟混凝土孔隙液中, 复合缓蚀剂具有协同效应, 对钢筋有良好的阻锈作用. 当D-葡萄糖酸钠、钼酸钠和硫脲浓度分别为750、250和500 mg·L^-1时, 对钢筋的缓蚀效率可达到94.5%. 应用软硬酸碱(HSAB)理论分析缓蚀机理, 可认为三组分复合缓蚀剂在钢筋表面共同形成保护膜而阻止钢筋的腐蚀.     

Role of hydroxyl group in cerium hydroxycinnamate on corrosion inhibition of mild steel in 0.6 M NaCl solution

The corrosion inhibition mechanism of cerium hydroxycinnamate compounds has been studied and compared as an effective corrosion inhibitor for steel in an aqueous 0.6?M NaCl solution. Surface analysis results showed that the surface of steel coupons exposed to solutions containing cerium hydroxycinnamate compounds has less signs of corrosion attack due to a formation of the protective film, while the surface of mild steel coupons exposed to 0.6?M chloride solution without inhibitor additions was severely corroded due to pitting. Electrochemical results performed a good inhibition performance and information of the formed protective deposit that hinders the electrochemical corrosion reactions with a dominance of anodic inhibition mechanism. The results also indicated that the addition of cerium hydroxycinnamate compounds to 0.6?M NaCl solution could mitigate electrochemical corrosion reactions, reduce protective and double layer CPE magnitudes, and improve protective and charge transfer resistances. Furthermore, cerium 2-hydroxycinnamate showed better efficient corrosion inhibitor in comparison with cerium 4-hydroxycinnamate for steel in aqueous media containing 0.6?M chloride ion.     

水性环氧铝粉涂层/碳钢体系的腐蚀电化学行为

应用电化学阻抗谱(EIS)和扫描振动电极技术(SVET)研究了碳钢基体上含人造缺陷的水性环氧铝粉涂层浸泡在3.5%NaCl溶液中的腐蚀电化学行为.结果表明,浸泡初期,涂层缺陷处为阳极活性区,涂层阻抗随时间延长逐渐降低,活性区逐渐扩展;之后,由于腐蚀产物的自修复作用使整个涂层/金属界面电化学反应活性降低,导致涂层阻抗快速增加.浸泡后期,由于腐蚀介质渗入到涂层/基体界面,出现了更多的阳极活性区,涂层产生破坏剥离.     

Incorporation of Reactive Corrosion Inhibitor in Waterborne Acrylic Polyurethane Coatings and Evaluation of its Corrosion Performance

Hydroxyl-epoxy phosphate (HEP) as a reactive corrosion inhibitor was innovatively synthesized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crosslinked with waterborne isocyanate curing agent, which was used to form waterborne HEP/acrylic polyurethane composite (HEP-APU) coatings on Q235 steel surfaces. Electrochemical impedance spectroscopy and polarization curves were applied to analyze the corrosion behavior of the HEP-APU coatings in 3.5wt% NaCl solutions. The results indicated that the HEP-APU coatings show a superior passivation property and efficient corrosion protection of Q235 steel. The waterborne acrylic polyurethane coating containing 0.5wt% HEP exhibited the best corrosion performance among all the coating specimens. The improved flash-rust resistance can be attributed to the introduction of the phosphate group which could form phosphate film on the steel substrate.