氧化亚铁硫杆菌和氧化硫硫杆菌的协同作用对Q235钢腐蚀行为的影响

采用失重法、交流阻抗测试和扫描电镜等手段研究了氧化亚铁硫杆菌(T.f)和氧化硫硫杆菌(T.t)的协同作用对Q235钢腐蚀行为的影响。结果表明,T.f和T.t的协同作用加剧了Q235钢的均匀腐蚀速率,混合菌体系中Q235钢的腐蚀失重远大于两种微生物单独存在体系。显微分析结果表明,T.t体系中金属没有出现点蚀,混合菌体系中Q235钢的点蚀坑较T.f体系中的小而浅,T.t的存在降低了Q235钢的局部腐蚀。     

硫酸盐还原菌对H68黄铜点蚀的影响

本文通过自腐蚀电位技术、交流阻抗技术以及动电位极化技术等电化学技术,研究了H68黄铜在硫酸盐还原菌中的腐蚀行为,并分析了硫酸盐还原菌的腐蚀机理和腐蚀特性.由实验结果得出,随着硫酸盐还原菌代谢活动的加强,铜电极的点蚀电位和开路电位具有一定的规律,并且H68黄铜的转移电荷呈现升降升的规律.在硫酸盐还原菌中的腐蚀行为比在无菌介质中强烈.硫酸盐还原菌代谢活动能降低溶液的pH值,破坏了铜电极表面的CuO的氧化膜,加速了铜电极的腐蚀,促进了金属的点蚀发生,使铜金属点蚀敏感性增加.     

硫脲对非调质钢在HCl酸洗溶液中的缓蚀作用

目的 研究硫脲(TU)对非调质钢在HCl溶液中的缓蚀作用.方法 通过动电位极化曲线、电化学阻抗谱研究硫脲对非调质钢在HCl溶液中的缓蚀效应,采用KH-7700型三维视频显微镜观察非调质钢的腐蚀形貌.结果 非调质钢在不合缓蚀剂的HCl溶液中的自腐蚀电位(Ecorr)为-0.566V,自腐蚀电流密度(Jcorr)为12.57 mA/cm2.随着HCl溶液中硫脲浓度的增加,非调质钢的自腐蚀电流密度(Jcorr)逐渐减小,反应电阻(Rct)逐渐增大,界面双电层电容Cdl降低,缓蚀效率逐渐增加,阴极极化曲线几乎重合,而阳极极化曲线逐渐正移.当HCl溶液中加入5g/L硫脲时,缓蚀效率达91.17％,效果好于市售酸洗缓蚀剂AS-30,能够有效消除非调质钢在HCl酸洗液中的腐蚀麻点.结论 硫脲对非调质钢在HCl溶液中具有明显的缓蚀效应,能够有效消除非调质钢酸洗过程中的腐蚀麻点.     

Passivity and Pitting Corrosion of X80 Pipeline Steel in Carbonate/Bicarbonate Solution Studied by Electrochemical Measurements

This work investigated the effects of chloride ions and hydrogen-charging on the passivity and pitting corrosion behavior of X80 pipeline steel in a bicarbonate-carbonate solution by electrochemical and photo-electrochemical techniques. It was found that a stable passivity can be established on the steel in the absence and presence of chloride ions. The hydrogen-charging does not alter the transpassive potential, but increases the passive current density. When chloride ions are contained in the solution, pitting corrosion will be initiated. The pitting potential is independent of the hydrogen-charging. Hydrogen-charging would enhance the anodic dissolution and electrochemical activity of the steel, but does not affect the pitting potential, which indicates that the charged hydrogen is not involved in the pitting initiation. However, hydrogen may accelerate the pit growth. Photo illumination could enhance the activity of the steel electrode, resulting in an increase of photo-induced anodic current density.     

Hg和Ga元素对Mg阳极材料组织和电化学腐蚀性能的影响(英文)

采用动电位极化、恒电流和交流阻抗测试方法研究了Hg和Ga元素对Mg2%Hg,Mg2%Ga和Mg2%Hg2%Ga合金电化学腐蚀性能的影响,并用扫描电镜、X射线衍射和能谱分析了上述合金的显微组织和腐蚀表面形貌。结果表明:Mg2%Ga合金是固溶体,Mg-2%Hg和Mg-2%Hg2%Ga合金的晶界有白色第二相。Mg-2%Ga合金的平均电位为1.48V,腐蚀电流密度为0.15mA/cm2,电化学活性差,耐腐蚀性能好。Mg-2%Hg-2%Ga合金的平均电位1.848V,腐蚀电流密度为2.136mA/cm2,电化学活性好,耐腐蚀性能差。MgHgGa合金的活化机制是Hg和Ga原子的溶解沉积。     

表面粗糙度对304不锈钢早期点蚀行为影响的电化学方法

采用动电位扫描、电化学阻抗谱和电化学噪声等方法研究了4种不同表面粗糙度304不锈钢电极在质量分数为3％的NaCl溶液中的早期腐蚀行为.随着不锈钢电极表面粗糙度的下降,304不锈钢自腐蚀电位与点蚀电位均有所上升;电荷转移电阻噪声电阻明显升高,而电位标准偏差与电流标准偏差则有所降低;粗糙度0.25μm的电极在阻抗谱低频区出...     

核电厂水池覆面用不锈钢钢板在硼酸水溶液中的点蚀行为

采用电化学方法研究了温度、Cl~-以及SO_4~(2-)含量对不锈钢板S30403、S32101和S32205在硼酸溶液中点蚀行为的影响。结果表明:3种材料的点蚀电位(Eb)和再钝化电位(Er)均随Cl~-含量的升高而降低,S32205不锈钢的点蚀电位和再钝化电位普遍高于S32101和S30403不锈钢的;存在临界温度(约60℃),当温度高于临界温度,S32205不锈钢的点蚀电位大幅降低,再钝化电位的临界温度介于40~60℃;SO_4~(2-)含量对3种材料点蚀电位和再钝化电位的影响不明显。S32205不锈钢的耐点蚀性能优于S32101和S30403不锈钢的,而S32101和S30403不锈钢的耐点蚀性能相当。     

敏化对不锈钢孔蚀性能的影响

用电化学测试技术研究了不同敏化处理的304不锈钢的耐孔蚀性能,探讨了Cl-浓度、温度和pH值对孔蚀电位Eb的影响。结果表明,敏化热处理导致Eb值下降;随Cl-浓度增加,介质温度升高,pH下降,使Eb值变负;不锈钢的晶间腐蚀使耐孔蚀性能变劣     

Electrochemical behavior of chalcopyrite in presence of Thiobacillus ferrooxidans

1 Introduction The bioleaching research has a great progress in metallurgy industry. A significant number of commercial applications have emerged and are able to compete with conventional processing, especially the application for the copper recovery. Fur…     

Intergranular corrosion and stress corrosion cracking of an aged AlCu alloy in 1 N NaCl solution

The susceptibility of an aged pure AlCu alloy with 4 wt% Cu to intergranular corrosion (IGC) and to stress corrosion cracking (SCC) has been studied in 1 N NaCl solution. For this purpose the time to failure of thin flat tensile samples under constant load has been determined in dependence of the electrode potential and compared with the electrochemical behaviour of unstressed samples. Below the pitting potential of pure aluminum in 1 N NaCl solution the tensile specimens never failed. Above this potential, failure did occur, and time to failure decreased with increasing electrode potential. Unstressed samples showed intergranular attack at potentials at least 40 mV higher than the pitting potential of pure aluminum. Metallographic examinations showed that mechanical stress accelerates the intergranular attack by a factor 10 to 100. Current densities calculated from the velocity of penetration under stress are in good agreement with values known from the pitting of pure aluminum. From the results obtained in this work the conclusion is that SCC of the aged AlCu alloy can be regarded as stress accelerated IGC.     

Erosion-corrosion of stainless steel under impingement by a fluid jet

The localised corrosion of 304L stainless steel is described by electrochemical measurements made under impact of a fluid jet of sodium chloride solution, in the absence of the entrained solid particles. Impingement by the fluid jet causes the open-circuit potential of 304L stainless steel in 0.6 M NaCl solution to increase with time until it attains the pitting potential. This is due primarily to acceleration of the cathodic reaction because the mass transfer rate of oxygen is increased under impingement by the fluid jet. Once the pitting potential has been achieved, the open-circuit potential decreases because of growth of stable pits. Fluid flow can itself thereby initiate stable pitting corrosion in open circuit.     

Die Lochkorrosion austenitischer Chrom-Nickel- und Chrom-Nickel-Molybdän-Stähle in schwefelsaurer Bromidlösung und ihre Inhibition durch Nitrationen

Pitting corrosion of austenitic chromium nickel and chromium nickel molybdenum steels in sulfuric acid containing bromides, and its inhibition nitrate ions In acidified bromide solution CrNi steels are attacked under pitting when a certain critical potential has been exceeded; this potential is higher than in the case of chloride containing solutions. Bromides are, consequently, less active than chlorides, but the pit density is considerably higher under idential corrosion conditions. While the pitting corrosion in chloride solutions can be considerably reduced by molybdenum addition to the steel, this effect is but little pronounced in the case of bromide solutions (with Mo additions up to 4% the potential is displaced by 0.2 V toward positive values). Mo additions around 2% are even dangerous since the pitting density is considerably increased in that range. Similar to the conditions in chloride solutions corrosion in bromide solutions is inhibited by nitrate additions; the potential limit is considerably higher in the bromide solution; this phenomenon points to stronger adsorption of bromide ions at the metal surface.     

304 不锈钢在氯化钠介质中点蚀缓蚀剂的研究

目的研究钼酸钠、葡萄糖酸钠及其复配物在氯化钠介质中,对304不锈钢点蚀的缓蚀作用。方法对钼酸钠、葡萄糖酸钠按不同配比进行复配得到不同缓蚀剂,采用极化曲线法分别测试在这几种缓蚀剂存在的条件下,304不锈钢在3.5%(质量分数,后同)NaCl溶液中的点蚀电位。结果单组分的钼酸钠、葡萄糖酸钠对在3.5%NaCl介质中的304不锈钢点蚀有一定的抑制作用,且两种缓蚀剂有明显的协同缓蚀效应。结论当复配缓蚀剂配比为c(钼酸钠)∶c(葡萄糖酸钠)=2∶1时,其缓蚀效果达到最佳,点蚀电位为436 mV。     

Dynamics of anodic process of gold electrode in thiourea solution in the presence of sulfur dioxide

1　INTRODUCTIONCyanidefreetechnologyofgoldextractionisanimportantissueinhydrometallurgy[1,2 ] .Thioureawasusedasanimportantmetallurgicalreagentduetoitsgoodselectivity ,low poisonousnessandhigheffi ciency[3,4 ] .Refs .[5 7]showedthatanodedissolv ingofgoldwillbeacceleratedifsulfurousacidorsul furdioxide (H2 SO3)isaddedintothioureasystem .Themechanismwasconsideredthatsulfurousacidwasinvolvedintotheelectrochemistryreactionofthesystem ,mainlyacceleratingdeoxidizationreactionofformamidinedisul…     

Localized attack of copper and brass in tap water: the effect of Pseudomonas

The presence of Pseudomonas fluorescens in artificial tap water (ATW) affects the composition of the oxide layer and the susceptibility to pitting corrosion of copper and 70/30 brass. The surface layer was investigated by means of a combination of electrochemical and spectroelectrochemical techniques involving cyclic voltammograms, potentiodynamic reduction curves, anodic polarisation curves, weight-loss tests and reflectance spectroscopy.In the sterile conditions the mass loss is lower in brass than in copper while the presence of bacteria enhances the attack in brass. Dezincification in inoculated electrolyte was revealed by microscopic observation, as well as by potentiodynamic reduction curves. Zn dissolution was also supported by spectroscopic evidence.Slow-rate voltamperometric curves were used to determine potential values characteristic of localized corrosion. In the presence of bacteria, the pitting potential moves towards more positive values for both materials but the difference between the repassivation and the pitting potential increases. Bigger and deeper pits can be seen in the presence of microorganisms.     

激光电子散斑干涉技术监测奥氏体不锈钢在NaCl溶液中的点蚀敏感性

用动电位极化和电化学阻抗等方法检测1Cr18Ni9Ti、304和316三种奥氏体不锈钢在3.5%NaCl溶液中的点蚀敏感性;用恒电位下的计时电流法结合激光电子散斑干涉技术（ESPI）实时监测这三种材料在3.5%NaCl溶液中阳极极化过程的表面动态变化及点蚀感应时间(τ)。结果表明,当电极表面发生点蚀时,激光电子散斑干涉图上会出现由点蚀产物扩散引起的亮斑。1Cr18Ni9Ti和 304不锈钢的τ值分别是1 s和9 s,316不锈钢的τ值大于50 s。由此可以判断1Cr18Ni9Ti的点蚀敏感性最大,304居中,316的点蚀敏感性最小。此结果与动电位极化和电化学阻抗等电化学方法得出的结果一致。激光电子散斑干涉技术可以做为一种实验室方法监测金属早期点蚀敏感性。     

预渗氮处理对20CrMnTi钢真空渗碳层耐蚀性能的影响

在真空渗碳前预先对20CrMnTi钢进行真空渗氮处理,采用OM、SEM和XRD研究了预渗氮处理对渗碳层显微组织及腐蚀形貌的影响,通过电化学测试和浸泡腐蚀质量损失来评价其耐蚀性能。结果表明,经过预渗氮处理的渗碳试样的渗层马氏体更加细小并且有大量渗碳体析出,耐腐蚀性明显提高,自腐蚀电流密度从1.3608×10^-5 mA·cm^-2下降到2.9817×10^-6 mA·cm^-2,自腐蚀电位由-0.7741 V提高到了-0.6672 V,其腐蚀速率和发生腐蚀的倾向大大降低,并且由质量损失得出的腐蚀速率仅为渗碳试样的一半。这主要是由于预渗氮+渗碳处理试样渗层细小的马氏体组织和渗碳体在腐蚀时会阻碍孔蚀的扩展从而降低腐蚀速率,并且渗层的氮原子会与溶液发生化学反应生成NH⁺₄及NO^-₂或NO^-₃,降低Cl^-对材料的腐蚀作用。     

Interpretation of electrochemically and chemically investigated corrosion behaviors of 316L SS in acid chloride environments

The electrochemical behavior of 316L stainless steel was investigated in acid chloride environments, and pitting potentials were determined electrochemically and chemically. An increase in the anodic maximum current density was observed upon decreasing the cathodic potential from which the scan was initiated to determine the polarization curve. To determine the critical pitting potential through the chemical method, the potential was increased by increasing the concentration of ferric ions in ferric chloride while holding the chloride ion concentration constant with sodium chloride. When 316L stainless steel was immersed in 15 g/1 of FeCl₃6H₂O containing the same chloride ion concentration as 5% NaCl with pH=2 at 57°C, the corrosion potential increased to 0.47 V (SHE) within two minutes due to initial passivation. Immediately after reaching 0.47 V (SHE), which was just above the pitting potential of 0.45 V (SHE) determined electrochemically in 5% NaCl (pH=2, 57°C), the corrosion potential continuously decreased, indicating the onset and propagation of pitting corrosion. A correlation between the electrochemical and chemical methods can be verified if the proper measurements are made and the observations are properly interpreted.     

Cu含量对一种新型Al-Mg-Si合金晶间腐蚀的影响

采用浸泡腐蚀实验和电化学实验研究了Cu含量变化和热处理条件对一种新型舰载飞机用Al-Mg-Si合金的耐腐蚀性能的影响.结果表明,添加Cu后,实验合金的 腐蚀方式由点蚀转变为晶间腐蚀,且腐蚀程度随Cu含量的增加而严重;与欠时效和过时效状态相比,T6态对晶间腐蚀较敏感,与晶界析出相的连续分布有关.电化学实验表明,所有实验合金均较快进入钝态;随Cu含量的增加,实验合金的自腐蚀电位向正向变化,腐蚀电流密度增加;随时效时间的延长,点蚀电位、晶间腐蚀的临界点位和自腐蚀电位逐渐向负向变化.而点蚀电位和自腐蚀电位随时效时间呈抛物线变化,晶间腐蚀的临界电位则呈直线变化.        

小孔腐蚀保护电位物理意义的研究

通过对Cr13,1Cr18Ni9Ti及1Cr18Ni9不锈钢小孔腐蚀模型电池及“闭塞”阳极电化学行为的研究,实验证明了小孔腐蚀的保护电位E_p是小孔内再钝化状态的宏观反映,而不是“免蚀电位”或者“腐蚀小孔内的自腐蚀电位”,从而澄清了此前对小孔腐蚀保护电位E_p物理意义的种种推测。