含砂海水中环氧树脂/Q235钢体系的冲刷腐蚀行为研究

目的 研究环氧树脂/Q235钢体系在含砂流动海水中的耐冲刷腐蚀性能.方法 采用旋转冲刷腐蚀试验装置进行不同流速、不同含砂量下环氧树脂/Q235钢体系的冲刷腐蚀试验,利用表面观测、电化学测试以及扫描开尔文探针(SKP)技术研究冲刷腐蚀后体系的腐蚀规律.采用计算流体动力学(CFD)方法模拟计算冲刷流场和砂粒分布.结果 高流速下的砂粒不断冲击涂层表面,导致涂层破损,使基体与海水直接接触,造成基体腐蚀,基体腐蚀又导致涂层的进一步破损.当冲刷流速在5～6 m/s之间时,涂层发生破坏,涂层底部腐蚀连接成片,生成片状腐蚀产物,腐蚀产物表面有较长裂缝.当含砂量达到1.5％(质量分数)时,涂层也发生破坏,但是其以孤立的腐蚀坑为主.Q235钢基体发生点蚀后,点蚀周围的腐蚀敏感性增加.随着腐蚀时间的增加,阳极区逐渐变宽,阴极区逐渐向外移动.腐蚀区域逐渐扩大,形成腐蚀通道.最终,腐蚀通道相互连接,从而在涂层下引起更大范围的腐蚀.结论 与含砂量相比,环氧树脂涂层的冲刷腐蚀对流速敏感性更高.     

基于固结试验和接触理论分析的铁锈力学性能

选取自然锈蚀、电解锈蚀两种锈蚀产物颗粒作为研究对象,采用X射线衍射(XRD)、显微镜观测等方法研究两者物理性能上的差异。通过改进的固结试验方法,同时引入Hertz弹性接触理论,对不同粒径的不同锈蚀产物进行不同荷载作用下的模量分析计算,得到了不同荷载与铁锈模量之间的关系,表明铁锈不是线弹性物质,铁锈模量随荷载呈线性增加趋势。在试验结果基础上,还考虑尺寸效应影响,提出了自然锈蚀产物颗粒的内部损失表达式,并对自然锈蚀产物颗粒的内部损失进行定量分析,可描述理想无损自然锈蚀产物的力学性能。     

Electrochemical Characteristics in Seawater for Cold Thermal Spray-Coated Al-Mg Alloy Layer

For corrosion protection of carbon steel in a marine environment,cold arc thermal spray coating was applied to the surface with Al and Al-Mg alloy wires.The surface hardness of Al and Al-Mg thermal spray coatings increased with Mg content.And the various electrochemical experiments were carried out to evaluate corrosion damage characteristics of the thermal spray coating layers.The Al and Al-Mg thermal spray coating layers presented negative potentials compared to carbon steel in corrosion potential measurements.And an anodic polarization experiment revealed a tendency of activation polarization with no passivation.Furthermore,the corrosion damage of the thermal spray coating layer in galvanostatic experiment was observed mainly at the defect area,and the Al-3Mg thermal spray coating layer presented less surface damages than others.In addition,the Al-3Mg thermal spray coating layer showed the lowest corrosion rate while having a sufficient driving voltage for cathodic corrosion protection.Therefore,it is an optimal thermal spray material for sacrificial anode.     

Effect of Microstructures and Textures on Different Surfaces on Corrosion Behavior of an as-Extruded ATZ411 Magnesium Alloy Sheet

The effect of textures on different surfaces of an as-extruded Mg-4 Al-1 Sn-1 Zn(ATZ411) alloy sheet on its corrosion behavior was systematically investigated. The microstructure was examined by optical/scanning electron microscopy. The texture was characterized by X-ray diffraction and electron backscatter diffraction. The corrosion performance was evaluated by immersion tests, electrochemical measurements, and corrosion morphology observation. The results showed that there were obvious differences in the corrosion morphology and corrosion resistance on different surfaces. The surface perpendicular to extrusion direction had better corrosion resistance and more uniform corrosion damage than that perpendicular to the normal direction and that perpendicular to the transverse direction in 3.5 wt% NaCl solution. The corrosion morphology was mainly determined by the distribution of the second phase and fine-grained regions. The corrosion rate was more related to the overall texture.     

An efficient image-based damage detection for cable surface in cable-stayed bridges

Since cable members are the major structural components of cable bridges, they should be properly inspected for surface damage and inside defects such as corrosion and/or breakage of wires. This study introduces an efficient image-based damage detection system that can automatically identify damages to the cable surface through image processing techniques and pattern recognition. The damage detection algorithm combines image enhancement techniques with principal component analysis (PCA) algorithm. Images from three cameras attached to a cable climbing robot are wirelessly transmitted to a server computer located on a stationary cable support. To improve the overall quality of the images, this study utilizes an image enhancement method together with a noise removal technique. Next the input images are projected into PCA sub-space, the Mahalanobis square distance is used to determine the distances between the input images and sample patterns. The smallest distance is found to be a match for an input image. The proposed damage detection algorithm was verified through laboratory tests on three types of cables. Results of the tests showed that the proposed system could be used to detect damage to bridge cables.     

The Corrosion Rate of Sintered Nickel in Acidified Chloride Solution

The corrosion rate of powder-metallurgy nickel in a 3% HCl + 5% NaCl solution is measured by gravimetric, volumetric, analytical, and electrochemical (polarization and impedance measurements) methods. A method of measuring the corrosion rate of sintered materials per unit visible or true surface, based on the analysis of frequency dependence of electrochemical impedance, is described. Limitations on using the methods of measuring the corrosion rate for porous materials are discussed.     

Enhancement of Corrosion Resistance of Zinc Coatings Using Green Additives

In the present work, morphology, microstructure, and electrochemical behavior of Zn coatings containing non-toxic additives have been investigated. Zn coatings were electrodeposited over mild steel substrates using Zn sulphate baths containing four different organic additives: sodium gluconate, dextrose, dextrin, and saccharin. All these additives are “green” and can be derived from food contents. Morphological and structural characterization using electron microscopy, x-ray diffraction, and texture co-efficient analysis revealed an appreciable alteration in the morphology and texture of the deposit depending on the type of additive used in the Zn plating bath. All the Zn coatings, however, were nano-crystalline irrespective of the type of additive used. Polarization and electrochemical impedance spectroscopic analysis, used to investigate the effect of the change in microstructure and morphology on corrosion resistance behavior, illustrated an improved corrosion resistance for Zn deposits obtained from plating bath containing additives as compared to the pure Zn coatings.     

The corrosion behavior and mechanism of X65 steel induced by iron‐oxidizing bacteria in the seawater environment

The corrosion behavior and mechanism of iron‐oxidizing bacteria (IOB) on X65 steel in seawater are studied. This study uses the methods of weight loss, electrochemical measurements, and surface analysis. The results show that the IOB increases the corrosion damage degree of steel. Pittings are observed in the medium with IOB. The potentiodynamic polarization curves show that the anodic reaction rate is accelerated in the corrosion process of IOB. The synergies in corrosion between the metal surface, abiotic corrosion products, and bacterial cells, and the pitting corrosion mechanism of X65 steel are discussed.     

酸性介质中N,N′-双(2-亚甲基吡啶)-1,2-亚氨基乙烷对AZ91D镁合金的腐蚀抑制作用(英文)

采用电化学方法研究N,N′-双(2-亚甲基吡啶)-1,2-亚氨基乙烷(BPIE)Schiff碱在0.010 mol/L HCl溶液中对AZ91D镁合金的腐蚀抑制作用。动电位极化曲线表明,BPIE Schiff碱是一种混合型缓蚀剂。电化学阻抗谱(EIS)测量证实了BPIE的腐蚀抑制作用。随着缓蚀剂浓度的增加,由于有更多的缓蚀剂吸附在AZ91D镁合金表面,电荷转移阻力减小,双电层电容减小。电化学噪声(EN)分析获得的数据在时间和频率域与EIS和极化曲线所得结果表现出良好的一致性。采用扫描电子显微镜(SEM)、X射线衍射(XRD)和能量色散X射线(EDX),研究BPIE的缓蚀作用。SEM照片显示,在存在BPIE的情况下,AZ91D合金表面的腐蚀损伤得到减轻。XRD分析显示,在存在BPIE的情况下,对应于富镁α相的谱峰强度增大,表明合金样品的腐蚀程度低。EDX分析也证实了BPIE的缓蚀作用。此Schiff碱化合物通过物理吸附在合金表面,吸附行为遵循Langmuir等温吸附模型。     

Steel corrosion and corrosion-induced cracking in recycled aggregate concrete

This study investigated four reinforced concrete mixtures with different replacement percentages of recycled coarse aggregate (RA). The corrosion rate was measured using an electrochemical workstation, and the corrosion-induced cracks on the concrete surface were observed using digital microscopy. The results show that the use of RA introduces more interfaces in concrete, which accelerates the steel corrosion process and corrosion-induced crack propagation in concrete cover. However, steel corrosion and the corrosion-induced cracking process in concrete are not significantly influenced by replacing a small amount (33% in the study) of coarse aggregate with RA.     

原子力显微镜在有机缓蚀剂研究中的应用

有机缓蚀剂具有低毒性和高性价比等优点,在低浓度的注射剂量下可以实现优良的缓蚀效果,被广泛应用于石油化工（碳钢）、电子工业（铜）、车辆船舶和航空航天工业（铝）,保护合金材料免受腐蚀危害。现有的电化学测试技术已经在有机缓蚀剂领域得以广泛应用,这种传统的研究方法可以提供有关界面电化学反应的平均动力学信息,但是无法直接解析缓蚀剂的吸附及作用机制。随着金属腐蚀与缓蚀剂研究的微观化和系统化发展,电化学分析手段逐渐与其他分析技术（如扫描电镜、X射线光电子能谱、拉曼光谱等）紧密结合,开展了对缓蚀剂作用机制的深入研究。在这些分析技术中,原子力显微镜（AFM）由于空间分辨率成像能力高,受工作环境和样品性质的局限较少,在有机缓蚀剂于金属/溶液界面的直观研究中起到了重要作用。本文结合近年来原子力显微镜在有机缓蚀剂领域的研究进展,简述了原子力显微镜的工作原理和几种操作模式,详述了AFM的接触模式在有机缓蚀剂研究中的普遍应用和其局限性,总结了AFM的敲击模式在表面活性剂吸附研究中的重要作用和研究现状并延伸到有机缓蚀剂的吸附研究,综述了AFM几个衍生功能（包括纳米刮擦、力-距离曲线、摩擦力和电化学原子力显微镜）在有...     

The influence of crystallographic orientation distribution on 316LVM stainless steel pitting behavior

In this research, the influence of crystallographic orientation on pitting corrosion susceptibility of 316LVM stainless steel surface has been investigated using orientation imaging microscopy (OIM) technique. It has been shown that the susceptibility of the surface to pitting corrosion depends strongly on the crystallographic orientation of the planes parallel to the surface. This has revealed an anisotropic nature of pitting initiation on the surface, suggesting that controlling the texture of the material can be considered as a means of ameliorating the material’s pitting resistance. The generalized spherical harmonic functions have been used to express the pitting susceptibility of various crystallographic planes. Using the proposed formula and the texture inverse pole figure of the investigated material (obtained from orientation distribution function, ODF), the pitting susceptibility index (PSI) of the surface is predicted based on texture measurements. The results obtained thus demonstrate a novel method of improving pitting resistance of SS316LVM by designing the desired texture.     

Modelling of interaction between corrosion-induced concrete cover crack and steel corrosion rate

Chloride-induced corrosion of steel reinforcement in concrete may cause severe damage to RC structures. This paper examines the interaction between corrosion-induced cover crack growth and corrosion propagation. The coupled micro- and macro-cell corrosion process involved in a typical chloride-induced corrosion is numerically simulated. Both oxygen concentration and electrical potential distribution within concrete cover are considered in the electrochemical analysis. A uniform thick-walled cylinder model is formulated to simulate the cover surface crack width evolution. Results show that macrocell corrosion rate may not change so much while microcell corrosion rate increases a lot as oxygen permeability increases with corrosion-induced cover crack.     

热处理对牙用Ti-12Zr合金组织与性能的影响

为了对Ti-12Zr合金在牙科的临床使用提供实验及理论依据,借助维氏硬度测量、电化学性能测试和扫描电子显微镜镜(SEM)的观察及X-射线衍射(XRD)的分析,研究了牙用Ti-12Zr合金经200、400、500、600和800℃加热(氧化)处理后合金的表面维氏硬度、形貌、结构及电化学性能。结果表明:经不同热氧化温度处理的Ti-12Zr合金表面能够生成不同厚度的ZrO2和(Ti,Zr)O2陶瓷层,其硬度比Ti-12Zr合金基材高;在人工唾液环境中,在500℃以下,随热氧化温度的升高,Ti-12Zr合金表面生成的陶瓷层耐腐蚀性能随着温度的升高而增加,500℃时,腐蚀电位Ecorr达到最大值(-18mV),抗腐蚀性能最好,超过500℃时,Ecorr又降低,抗腐蚀性能变差。     

闪镀镍对冷轧板表面耐蚀性的影响

目的提供一种提高冷轧板(普冷板)表面耐蚀性的新方法。方法在冷轧板表面闪镀镍。利用扫描电镜观察表面形貌,利用EDS能谱测定表面沉积的镍元素含量,测试Tafel极化曲线和交流阻抗谱,研究闪镀镍对冷轧板表面状态和电化学性能的影响。采用点滴实验和湿热实验评价冷轧板表面的耐蚀性能。结果当闪镀温度为45~55℃,电流密度为3~6 A/dm2,闪镀时间为15~20 s时,沉积到基板表面的镍元素原子数分数达到40.1%以上。此时,冷轧板表面的点滴变色时间明显延长,在潮湿条件下的锈蚀面积明显减少。电化学测试也发现在冷轧板表面闪镀镍后,表面腐蚀电流明显降低,交流阻抗弧变大。结论闪镀镍可以改变冷轧板的表面状态和电化学性能,使冷轧板的表面活性和腐蚀倾向有所降低,从而提高冷轧板表面的耐蚀性能。该研究为冷轧板存储、运输、使用过程中的防锈提供了一种新方法,且方法简单有效、环保、实用。     

The role of different surface damages in corrosion process in alkaline sour media

By applying different electrochemical methodologies to 1018 carbon steel/different electrolytic media interfaces, surfaces with generalised and blistered damages, commonly present in the oil refinery catalytic plants, were obtained. Afterwards, a freshly polished carbon steel surface as well as the damaged surfaces were characterised by electrochemical impedance spectroscopy and scanning electronic microscopy (SEM). The SEM results reveal that the damaged surfaces present films with different physical properties.In spite of the surface modification, the corrosion mechanism of these interfaces in a medium simulating catalytic plants condensates of the refineries in Mexico (0.1 M (NH₄)₂S, 0.4 mM NaCN (10 ppm CN⁻), pH=8.8) turned out to be the same. It was also found that the corrosion process presents the following steps: charge transfer resistance of steel oxidation in the metal/corrosion product film interface and the diffusion processes of Fe²⁺ and H^o ions through the corrosion product film. It was demonstrated that when there was no damage on the surface (freshly polished surface), a homogeneous film was formed instantaneously upon introducing carbon steel into the sour media. The corrosion process in this film occurs in three stages. On the surface with generalised corrosion the three stages are favoured, particularly that of atomic hydrogen process (inducing blistering). Meanwhile, the blistered surface presents a higher charge resistance of steel oxidation and the Fe²⁺ and atomic hydrogen diffusions through the corrosion products are slower than those presented on the other surface states.     

Tribocorrosion behaviour of HVOF cermet coatings

The main purpose of this work is to analyze the degradation mechanisms induced on industrial HVOF cermet coatings by tribocorrosion. Tribocorrosion of cermet coatings is a subject that has not been widely analyzed in research studies: in fact, while many works dealing with wear or corrosion of HVOF cermet coatings are published, studies relevant to the combined processes (wear and corrosion) are relatively few.The tribocorrosion mechanisms of the cermet coatings were studied in a sodium chloride solution under sliding wear, trying to combine and integrate differently produced mechanical and electrochemical damage phenomena.Electrochemical techniques such as potentiodynamic polarization curves as well as potentiostatic (I vs t) or galvanostatic (E vs t) methods were used in order to stimulate and to interprete tribocorrosion degradation mechanisms.It was shown that coating post grinding, which is a mechanical operation usually performed after the deposition of conventional cermet coatings in order to obtain a desired roughness, could produce structural damages, which can greatly affect the mechano-chemical behaviour of the cermet coatings.Mainly abrasive-adhesive wear mechanisms were observed on the coating surface and sometimes, depending on coatings mechanical properties (fracture toughness), cracks developed during wear causing the coating continuity breaking. In the latter case, the degradation mechanism is no longer governed only by surface tribocorrosion, but undermining corrosion can occur, greatly affecting sample performances and promoting coating detachment.Cr₃C₂-NiCr coatings, under all the selected experimental conditions, showed good barrier properties and substrate corrosion was never observed. Moreover, when chromium was added to the metal matrix of WC-Co based systems, tribocorrosion behaviour was enhanced and the lower tribocorrosion rates were measured.Finally, it was shown that electrochemical techniques can be used to govern the coating corrosion processes and to interpret the main degradation mechanisms, even though they seem not to provide a precise quantitative analysis of tribocorrosion.     

铜合金表面超音速微粒沉积镍基涂层的耐蚀性能研究

目的研究铜合金表面镍基合金涂层的耐腐蚀性能,解决铜合金表面腐蚀损伤问题。方法采用超音速微粒沉积技术在黄铜表面制备镍基合金涂层,通过电化学方法和中性盐雾实验对黄铜基体及镍基合金涂层的耐腐蚀性能进行测试。结果涂层的腐蚀电流密度较基体降低了34倍。涂层表面生成的连续且致密的氧化膜阻止了腐蚀的进一步发生,在盐雾腐蚀时间进行到500 h时,腐蚀速度接近于零,涂层腐蚀缓慢。结论超音速微粒沉积技术可以制备耐腐蚀性能优异的镍基合金涂层,并且可以显著提高黄铜的基体耐蚀性。     

Influence of Twinning Texture on the Corrosion Fatigue Behavior of Extruded Magnesium Alloys

Bio-magnesium alloys have received great attention due to their degradability and biocompatibility.Corrosion fatigue failure is a huge challenge in vivo for bio-magnesium alloy implants.Understanding the eff ects of twinning textures on the corrosion fatigue of magnesium alloys is meaningful for the applications.In the current study,pre-compression strains of 2% and 4% were carried out on extruded rods.The effects of twinning texture on the corrosion performance and corrosion fatigue resistance were investigated.The hydrogen evolution tests indicated that twinning texture enhanced the corrosion resistance of longitudinal cross section by improving uniformity of surface energy.The results of corrosion fatigue tests indicated that the differences in mechanical damage caused by twinning texture dominated the corrosion fatigue behavior under high stress amplitude.The secondary cracks of surface deteriorated the corrosion fatigue resistance of the original specimens under low stress amplitude.The compact corrosion film and the re-passivation of matrix suppressed the hydrogen induced cracking,thereby improving the corrosion fatigue resistance of the pre-compression specimens.     

磷化处理对无铬钝化热镀锌板耐蚀性能的影响

研究了磷化处理工艺对无铬钝化热镀锌板耐腐蚀性能和表面形貌的影响。采用扫描电镜对其表面形貌进行分析，同时与未经过磷化处理的钝化板表面形貌进行对比；采用电化学阳极极化曲线方法和电化学阻抗法对磷化处理后钝化板的耐腐蚀性能进行了研究。在钝化板膜重为0.8 g/m²的情况下，经磷化处理的钝化板表面钝化膜完好，没有发现锈蚀或钝化膜剥落现象；经磷化处理的钝化板自腐蚀电位和阳极电流密度不变，阴极电流密度和自腐蚀电流密度有所提高；Nyquist图的高频部分在磷化处理前为容抗弧，磷化处理后出现具有Warburg阻抗的直线，说明磷化处理后钝化膜表面出现扩散过程。 研究表明，钝化板经过磷化处理后表面未形成磷化膜，耐腐蚀性能仍来自原钝化膜，经磷化处理的钝化板的耐腐蚀性能有所降低。因此，现有常规的磷化处理并没有增加钝化板的耐腐蚀性能，如果有需要提高钝化板耐腐蚀性能的要求，必须针对无铬钝化板研制专用的磷化液和磷化工艺。