Corrosion behavior of Ti‐xNb‐13Zr alloys in Ringer's solution

Ti‐6Al‐4V alloy has been widely used in restorative surgery due to its high corrosion resistance and biocompatibility. Nevertheless, some studies showed that V and Al release in the organism might induce cytotoxic effects and neurological disorders, which led to the development of V‐free alloys and both V‐ and Al‐free alloys containing Nb, Zr, Ta, or Mo. Among these alloys, Ti‐13Nb‐13Zr alloy is promising due to its better biomechanical compatibility than Ti‐6Al‐4V. In this work, the corrosion behavior of Ti, Ti‐6Al‐4V, and Ti‐xNb‐13Zr alloys (x = 5, 13, and 20) was evaluated in Ringer's solution (pH 7.5) at 37 °C through open‐circuit potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. Spontaneous passivity was observed for all materials in this medium. Low corrosion current densities (in the order of 10^?7 A/cm²) and high impedance values (in the order of 10⁵ Ωcm² at low frequencies) indicated their high corrosion resistance. EIS results showed that the passivating films were constituted of an outer porous layer (very low resistance) and an inner compact layer (high resistance), the latter providing the corrosion resistance of the materials. There was evidence that the Ti‐xNb‐13Zr alloys were more corrosion resistant than both Ti and Ti‐6Al‐4V in Ringer's solution.     

海水拌和混凝土中不锈钢筋早期腐蚀电化学行为研究

目的 研究海水拌和混凝土中不锈钢筋早期腐蚀电化学行为,从而有效解决海水海砂混凝土中的钢筋腐蚀问题。方法 采用压滤法提取了海水拌和水泥浆体孔溶液,监测了孔溶液pH值和氯离子浓度随时间的变化,采用开路电位(OCP)、交流阻抗(EIS)等电化学方法,结合扫描电子显微镜SEM(EDS)、背散射(BSE)形貌观测手段研究了不锈钢筋腐蚀电化学行为,深入分析了不锈钢筋在海水拌合水泥浆体中的钝化动力学过程。结果 尽管在早期304和316L不锈钢筋电位降至负值,均低于−0.35 V,氯离子浓度达到0.7 mol/L,但并未发生活化腐蚀,均可以发生正常钝化现象,海水拌和水泥浆体中316L不锈钢极化阻抗相比对照组(非海水拌合样品)有提升,腐蚀速率更低。随着水泥水化过程的发展,腐蚀电流密度逐渐降低至较低水平,304不锈钢腐蚀电流密度约为0.014 μA/cm²,316L不锈钢电流密度低于0.006 μA/cm²,展现出较高的耐腐蚀性能。海水拌和水泥浆体的电阻率与对照组浆体有一定差异,但整体相差较小。结论 304和316L不锈钢尽管在早期可以发生正常钝化现象,电化学结果体现出较高的耐蚀性能,但其在服役期的氯离子临界浓度值及脱钝机理需要进一步研究。     

Corrosion behavior of Mg-Zn-Ca amorphous alloys with Nd addition in simulated body fluids

The effects of Nd addition on corrosion behavior of Mg66Zn30Ca4 amorphous alloys in simulated body fluids （SBF） were studied in this paper. Electrochemical properties of the samples before and after corrosion were determined. Surface morphologies of samples after immersion in SBF at 37 ℃ for different times were observed under scanning electron microscope （SEM）. Results show that the corrosion resistance of Mg-based alloys in SBF is improved with the addition of Nd element. The electrochemical properties indicate that microalloying Nd element to the alloys leads to an ennoblement in the open circuit potentials of the alloys and a decrease in the anodic current density in SBF, especially for the Mgee66-xZn30Ca4Ndx alloys with Nd content of 1.0at.%-1.5at.%. It was observed that the surface morphologies of the alloys immersed in SBF change with the Nd addition. A flake- like structure parallel to the alloy substrate formed on the surface of 1.0at.% Nd-containing alloy immersed in SBF for 7 days improves the corrosion resistance of the amorphous alloys by blocking the corrosion liquid from attacking the alloys.     

碳钢在混凝土模拟溶液中的腐蚀测试研究

采用失重法、电阻法和方阻法测试碳钢在混凝土模拟溶液中的腐蚀深度,并利用极化曲线、交流阻抗测试探讨腐蚀电化学特征。在腐蚀深度为0.08 mm范围内,电阻法、方阻法与失重法测量的腐蚀深度最大差值分别为6.30μm和0.98μm,测量结果有较好的一致性。碳钢在浸泡开始时,表面有一层钝化膜,阻抗谱为单容抗弧;继续腐蚀,碳钢从钝化转变为活化,表面钝化膜遭到破坏,腐蚀溶解不断进行。     

Electrochemical behavior of AISI 302 austenitic stainless steel in coal chemical high-salt wastewater

In this study, the effect of grain size and grain boundary characteristic distribution on the corrosion resistance of AISI 302 austenitic stainless steel in simulated coal chemical high-salt wastewater was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The grain size of the heat-treated sample is significantly increased and contains a greater fraction of high-angle grain boundaries (HAGBs) and twin content. As the heat treatment temperature and time increase, the passivation current density increases, which makes the passive film more susceptible to attack. The coarse-grained microstructure has exhibited worse pitting resistance due to its higher fraction of the HAGBs.     

304不锈钢晶间腐蚀发展过程的阻抗谱分析

研究了敏化态304不锈钢在10%草酸溶液中电解浸蚀不同时间的腐蚀形貌及产生晶间腐蚀后的电化学阻抗谱特征并拟合了电化学阻抗谱。结果表明：钝化膜表面界面电容Cc及晶间腐蚀活性区界面电容Cd随敏化态不锈钢晶间腐蚀程度的加剧呈上升趋势,电荷传递电阻Rt呈现下降趋势,与晶间腐蚀的发生和发展有一定的对应关系。研究结果为运用电化学阻抗谱技术检测不锈钢晶间腐蚀提供了必要的依据。     

湿法磷酸中不锈钢腐蚀的电化学分析

试验以湿法磷酸为体系，以316L和904L不锈钢为研究对象，采用动电位扫描测试了不同杂质组成和温度对两种不锈钢的影响，并对两种材料不同电位下的Nyquist图谱进行了测试。试验从电化学特征参数致钝电流密度ic、维钝电流密度ip、膜的破裂电位Eb和自腐蚀电位Ecorr以及交流阻抗阻力对两种材料的耐蚀性差异进行了分析。     

Stainless steel crevice corrosion testing in natural and synthetic seawater

Susceptibility of stainless steel to crevice corrosion in natural and synthetic seawater was investigated by a new test method, developed by a research group, CrevCorr, of the Marine Working Party of the European Federation of Corrosion. The method was defined on the basis of a Round Robin test performed by twenty laboratories over the world [1, 2]. Among them was our Institute at the Adriatic coast. Geometry of the crevice model, gasket materials, finishing of metal surface and the electrochemical potential increase rate were strictly defined. The monitoring of the free corrosion potential of two austenitic steels and a duplex steel, in the constant flowing conditions, as well as the redox potential, temperature, chloride and oxygen content, have been carried out during six months in the natural seawater from the Adriatic Sea at the location in Dubrovnik, Croatia. Sharp drop of the corrosion potential was used as an indication of the crevice corrosion initiation. After exposure to the seawater eventual crevice damage on a steel specimen was detected by visual and microscopic inspections. In the synthetic seawater the organic component was simulated by glucose and glucose oxidase [3, 4]. The monitoring of the free corrosion potential and the redox potential was performed at 20, 30 and 40°C during five days, and results compared with those obtained in the natural seawater at same temperatures.     

镀锡薄钢板在NaCl溶液中的腐蚀行为(英文)

应用电化学阻抗谱技术研究镀锡薄钢板在0.5mol/LNaCl溶液中的腐蚀过程,结合SEM、SPM、XRD、XPS技术表征腐蚀产物的形貌和腐蚀产物的结构。结果表明:腐蚀过程中镀锡层的电阻Rc值基本不变而电荷转移电阻Rct值下降了2个数量级,表明镀锡层基本没有发生腐蚀而基底金属碳钢则不断遭到腐蚀。镀锡薄钢板在0.5mol/LNaCl溶液中的腐蚀类型主要是对镀锡层缺陷处暴露的基底金属碳钢的腐蚀,其腐蚀产物主要是γ-FeOOH。     

Corrosion resistance of different steel grades in the geothermal fluid of Molasse Basin

Long‐term corrosion resistance of carbon steels grade API L80 and API Q125 has been evaluated by means of electrochemical measurements and exposure tests in the Molasse Basin, one of the most important geothermal fluids in Europe. In addition, the localized corrosion resistance of the duplex stainless steel alloy 2205 and the austenitic stainless steel grade 316L was determined at 100 and 150 °C. In general, investigated materials showed a remarkable resistance to uniform and localized corrosion. Their corrosion behaviour at service conditions is discussed in this paper.     

电化学测量技术在不锈钢点蚀研究中的应用与进展

不锈钢在含有侵蚀性离子的介质中极易发生点蚀,点蚀的存在不仅降低了不锈钢件的整体强度,严重时甚至会导致设备穿孔,造成严重的经济损失。因此,关于不锈钢点蚀行为的研究技术在防腐蚀、建筑、以及石油化工等领域备受关注。以各种技术及相关化学原理为依据,着重综述了近十年国内外电化学测量技术(包括极化曲线测量技术、电化学阻抗谱技术以及扫描电化学显微镜技术等)的研究进展,评述了其在腐蚀研究领域中的应用现状、前景以及不足。     

Localized corrosion of (lean) duplex stainless steels in immersion units of urban wastewater treatment plants

With lower alloying cost and higher mechanical properties, lean duplex stainless steels can be an alternative to the more commonly used austenitic stainless steels. However, these alloys are still not the preferred choice, probably due to a lack of field experience. A study was thus initiated in view of defining the limits of use of selected (lean) duplexes for urban wastewater treatment units. The present paper shows the localized corrosion performance of selected lean duplexes in chloride contaminated solutions. The results are compared with austenitic S30403 and S31603 and with the more standard duplexes S82441 and S32205. The effect of welding was also investigated. Exposures in field municipal wastewater plants were conducted for 1 year in low and high chloride content units. The results show that lean duplexes S32101 and S32202 can be used as alternatives to S30403 and S31603 in low chloride electrolytes. At 500 ppm of chloride content, duplex stainless steel S32304 showed better corrosion resistance than S30403 and S31603. For higher chloride contents (1000 ppm and above) the standard duplexes S82441 and S32205 shall be preferred.     

Corrosion behavior of 3C magnesium alloys in simulated sweat solution

AZ series Mg alloys AZ31, AZ61, and AZ80 are widely applied in 3C (computer, communication, and consumer electronic) industry. Their corrosion characters in simulated sweat solution have been investigated by electrochemical technology, surface analysis, and pH measurements. Electrochemical test results showed that the three magnesium alloys revealed different corrosion resistance (R_t) in simulated sweat solution, R_t(AZ31) < R_t(AZ61) < R_t(AZ80). Three major components of simulated sweat solution played different roles during corrosion processes. Lactic acid was a kind of strong erosive medium for the magnesium alloys, and NaCl can induce pitting corrosion on alloys surface, while urea acted as a corrosion inhibitor. The corroded surface morphology of the three magnesium alloys was observed using scanning electron microscopy (SEM) and corrosion products were analyzed by X‐ray diffraction (XRD). Result of pH measurement tests showed that there were differences in climbing speed and final values of pH for the three magnesium alloys in simulated sweat solution.     

Corrosion behaviors of carbon steel induced by life activities of Phaeodactylum tricornutum in a marine environment

Microbiologically influenced corrosion induced by bacteria has been studied for many years. Corrosion is known to be sensitive to the presence of microalgae, such as Phaeodactylum tricornutum. However, the life activity of P. tricornutum that influences the general and localized corrosion of carbon steel is not fully understood. The current study uses a combination of immersion tests and electrochemical experiments with a detailed surface characterization to reveal the naturally formed corrosion products with/without the presence of P. tricornutum. The results show that samples suffer from pitting corrosion and the averaged pit depths are approximately 15 μm under a light–dark cycle condition or a 24-h constant light condition. Meanwhile, the corrosion products are mainly comprised of γ-FeOOH and Fe₃O₄ in a constant light condition. However, γ-FeOOH, Fe₃O₄, and FeCO₃ are found in a light–dark cycle. This study proposes the fundamental mechanisms of the effect of P. tricornutum life activities on the corrosion performance of Q235 carbon steel, to fulfill the knowledge gaps of the presence of microalgae inducing the general and pitting corrosion of carbon steel.     

Localized corrosion of lean duplex stainless steels in H2S-containing wet atmosphere from urban wastewater treatment units

With lower alloying costs and higher mechanical properties, lean duplex stainless steels can be a good alternative to the more commonly used austenitic stainless steels. A study was initiated to define the limits of the use of lean duplex stainless steels for urban wastewater treatment (WWT) units. This paper gives and discusses the corrosion results in an aerated wet atmosphere containing H₂S at different levels. Exposures were performed both at laboratory scale and in the field WWT plant for 1 year. A specific probe was also designed to study the corrosion process below water condensate film contaminated with H₂S. Under such conditions, the properties of stainless steel were strongly modified with an enhanced risk of localized corrosion. The results obtained on lean duplex materials (UNS S32101, S32202, and S32304) are compared with austenitic UNS S30403 and UNS S31603 and with the more standard duplexes UNS S82441 and UNS S32205. The results show that lean duplexes can be used in aerated wet atmospheres in case of moderate contamination of H₂S (<10 ppm) and chloride (<200 ppm). For higher contaminations (e.g., H₂S around 100 ppm/chloride around 1000 ppm) the duplex S32205 should be preferred.     

加速腐蚀实验研究碳钢的大气腐蚀行为

目的快速研究大气环境对钢制输电铁塔腐蚀的影响。方法采用室内加速腐蚀实验,研究碳钢试样在湿度和SO2浓度不同的气氛中的腐蚀行为。结果用极化曲线法测得的金属腐蚀速率与失重法测得的结果具有很高的一致性。相对湿度较低时,改变腐蚀性气体的浓度,对碳钢的腐蚀影响不显著;碳钢在高湿度的含SO2气氛中会发生严重腐蚀。结论降低湿度是防止或减缓碳钢在含SO2气氛中腐蚀的有效途径。     

Corrosion behavior of a superduplex stainless steel in chloride aqueous solution

Super duplex stainless steels (SDSS) have been widely used as structural materials for chemical plants (especially in those engaged in phosphoric acid production), in the hydrometallurgy industries, and as materials for offshore applications due to their excellent corrosion resistance in chloride environments, compared with other commercial types of ferritic stainless steels. These alloys also possess superior weldability and better mechanical properties than austenitic stainless steels. However, due to their two-phase structure, the nature of which is very dependent on their composition and thermal history, the behavior of SDSS regarding localized corrosion appears difficult to predict, especially in chloride environments. To improve their final properties, the effect of the partition of the alloying elements between the two phases, and the composition and microstructure of each phase are the key to understanding the localized corrosion phenomena of SDSS. This paper concerns the effects of the SDSS microstructure and heat treatment on the SDSS corrosion resistance in aqueous solutions, containing different amounts of NaCl at room temperature.     

水轮机用不锈钢的电化学腐蚀性能研究

对含沙水域水轮机用 1Cr18Ni9Ti和 0Cr13Ni5Mo材料静态失重率、含沙自然水中电化学腐蚀性能进行了测试 ,研究了不同冲蚀速度、不同浆料含沙量条件下试验材料的腐蚀性能 ,结果表明 :含沙自然水或其它酸性介质中 ,该材料的腐蚀不容忽视 ;随着冲蚀速度和浆料含沙量的增加 ,试验材料的腐蚀失重率都增加 ,且因磨损与腐蚀的促进作用的不同而不同