电化学对循环冷却水系统碳钢的结垢与腐蚀影响

为探究电化学对循环冷却水系统碳钢材料结垢和腐蚀的影响,构建了以Ti/RuO₂阳极和Ti网阴极为核心的电化学处理系统,将其分别与旋转腐蚀速率仪和循环冷却水动态模拟系统进行联用。首先通过除垢效果和电流效率对电化学系统进行参数优化,实验结果显示,15V电压、120min处理时间为最优电化学处理参数。电化学联用旋转腐蚀速率仪实验结果显示,对于不同硬度的水质,电化学嵌入后均可降低碳钢表面垢沉积速率。XRD和SEM分析表明,碳钢表面水垢晶型以方解石为主转化为以文石为主。但当水质为软水时,电化学嵌入可明显加剧碳钢腐蚀速率;而当电化学嵌入硬水与高硬水水质时,挂片表面可形成均匀、致密的Fe₃O₄层,碳钢腐蚀速率由0.60mm/a、0.54mm/a分别降至0.47mm/a、0.32mm/a。电化学联用循环冷却水动态模拟装置实验结果显示,嵌入电化学模块后,循环冷却水模拟系统的污垢热阻均显著降低。经数据分析,当水质为软水时,嵌入电化学系统后碳钢腐蚀速率增大,而当水质为高硬水时,碳钢腐蚀速率分别由0.12mm/a、0.15mm/a降至0.10mm...     

地热水腐蚀结垢趋势的判断和计算

地热水供暖系统的运行会出现腐蚀结垢现象,对地热水腐蚀结垢趋势做出了计算和判断。工程实例表明,在地热水的Cl-物质的量分数大于25%时,用雷诺兹指数判断有局限性,此时,应结合拉申指数进行水质判断,才能使判断结果符合实际。     

pH、离子浓度、温度对20A碳钢在氯化钠溶液中电化学腐蚀行为的影响

报道通过电化学工作站、扫描电子显微镜、XRD衍射仪及原子分光光度仪研究pH、离子浓度、温度对20A碳钢腐蚀行为的影响。根据实验结果分析认为：室温（10℃C）,pH=8下,OH^-与Cl^-在材料表面发生竞争吸附,低浓度氯离子溶液中OH^-对材料的腐蚀起到了较好的抑制作用;在高浓度氯离子溶液中,Cl^-对OH^-的竞争取得优势,Cl^-的侵蚀作用破坏了OH对电极表面的保护,使得碳钢的腐蚀加剧;随着温度的升高,加速了溶液离子的扩散,使得OH^-对电极的保护遭受破坏,氯离子的迁入能力增强,导致碳钢的Rct递减,Icorr增大;在70℃、0．1mol／LCl^-溶液中挂片6h,试片表面可以看到明显的两层结构,外层为疏松的Fe3O4腐蚀产物,内层可能是Fe（OH）3。     

对煤化工生产过程中的防止腐蚀结垢的技术探讨

现阶段煤化工生产中,由于该生产工艺的不同,在设备生产阶段会出现一定的腐蚀与结垢现象.这种腐蚀结垢会对煤化工生产起到不同程度的负面影响.本文主要介绍了煤化工生产概述,详细论述了煤化工生产阶段防止腐蚀与结构的处理技术,从而提高煤炭资源的利用率,有效降低煤炭的损耗,以供相关工作人员借鉴分析.     

pH值和氯离子浓度对碳钢在酸溶液中的腐蚀电化学行为的影响

本文研究了溶液pH值和Cl~-浓度对碳钢在酸溶液中的腐蚀电化学行为的影响。结果表明,OH~-和Cl~-都参与了碳钢的阳极溶解过程,反应级数分别为0.3和0.5;b_α和b_κ分别为55mV和115mV。提出了碳钢在含Cl~-的酸溶液中阳极溶解反应的动力学式及阴极析氢反应的动力学式。实验结果还证明,在pH值与Cl~-浓度两者对碳钢的腐蚀电位φ_c和腐蚀电流密度i_c的影响之间没有交互效应。     

热轧碳钢SPHC在天津大气环境中的腐蚀行为

针对热轧钢SPHC的大气腐蚀问题,通过在天津自然环境下开展为期1年的SPHC钢大气暴露试验,依托腐蚀动力学分析、锈层形貌观察、腐蚀产物成分分析、电化学测试等研究了SPHC钢在天津大气环境中的腐蚀行为.结果表明,在暴晒6个月时,SPHC钢的腐蚀速率开始下降,腐蚀产物主要为γ-FeOOH、α-FeOOH和Fe3O4,随着暴露时间的增加γ-FeOOH逐渐向更稳定的腐蚀产物转化,表面较为致密的腐蚀产物含量增多,同时锈层不断增厚形成了双层结构,对基体的保护性逐渐增强,整体耐蚀性不断提高.     

饱和指数法在萨南油田结垢预测中的应用

采出井结垢是三元复合驱技术面临的主要问题之一,目前主要依据采出液pH值及成垢离子浓度进行判定,存在判别参数多、主观因素影响大、操作难度大的问题。因此,本文通过应用饱和指数结垢预测技术,不仅提高了工作效率和准确率,同时也实现了结垢状况的量化预测,为防垢措施实施提供准确依据。     

煤化工生产过程中的防止腐蚀结垢的技术措施

煤化工生产过程中,由于生产工艺的影响,会出现不同程度的腐蚀和结垢的现象,必须采取必要的处理措施,预防腐蚀和结垢现象的发生,提高煤化工生产设备的使用寿命,降低煤化工生产的成本,最大限度地提高煤化工生产的效率。     

蒸汽锅炉腐蚀与结垢机理研究及技术应用

本文深入研究石油石化工业中蒸汽锅炉烟管及炉膛腐蚀结垢的机理及危害,探讨了钠离子交换器软化、海绵铁除氧配套的炉外水处理技术,较好地解决了燃气蒸汽锅炉腐蚀结垢问题。     

Features of electrochemical noise generated during pitting of inhibited A516-70 carbon steel in chloride solutions

The features of electrochemical noise generated during pitting of A516-70 carbon steel in chloride solutions containing Na2CrO4 were investigated. Polarization curves showed that the threshold Cl– concentration in 0.01m Na2CrO4 solution to initiate pitting and the threshold CrO42– concentration in 0.1m NaCl solution to maintain passivation for A516-70 carbon steel were approximately 0.1m and 0.01m, respectively. Noise measurements indicated that above the critical Cl– concentration, the stochastic current fluctuations appeared after 5h of immersion, which was an indication of pit initiation. Increasing CrO42– concentration to 0.05m led to the production of symmetrical current spikes at the start of immersion. The noise pattern changed to frequent fluctuations with small amplitude during immersion. Noise analysis in the frequency domain showed that pitting initiation was characterized by the slope of the PSD plot approaching -2. Extending the immersion time decreased the pitting initiation rate, as indicated by the decreased PSD slope and increased PSD frequency.     

Corrosion of carbon steel in sodium methanoate solutions

The behaviour of steel electrodes in sodium methanoate solutions was studied by coupling electrochemical techniques (voltammetry, OCP vs. time) with in situ micro-Raman spectroscopy analyses of the corrosion products. The polarisation curves depended strongly on the methanoate concentration. For the smallest concentration (10⁻³ mol L⁻¹), the current density increased regularly with the applied potential. So the behaviour of the electrode was typical of an active material. In contrast, for the largest concentration (10⁻¹ mol L⁻¹), the curves obtained were typical of a passive material. Methanoate ions favoured growth and stability of a passive oxide film more likely by adsorbing on its surface. The polarisation curve obtained for the intermediate concentration (10⁻² mol L⁻¹) was unusual and testified of an imperfect passivation of the steel surface. Finally, steel electrodes were left at the open circuit potential in the methanoate solutions. In any case, the passivity was rapidly lost and a general corrosion of the surface took place. In situ Raman spectroscopy analyses at the early stage of the corrosion process demonstrated that the first product to form was a green rust, GR(HCOO⁻). It was oxidised later into γ-FeOOH (lepidocrocite) by dissolved O₂. The process is then typical of what is usually observed in neutral or alkaline media, whatever the anions present and responsible of the GR formation. A new and detailed characterisation of GR(HCOO⁻) by X-ray diffraction was performed and a crystal structure is proposed.     

Electrochemically induced self-assembly of alkanethiolate adlayers on carbon steel in aqueous solutions

The electrochemical behavior of carbon steel was studied in near neutral buffered aqueous solutions saturated with mercaptoundecanoic acid (MUA) and dodecanethiol (DT) by using electrochemical techniques combined with X-ray photoelectron spectroscopy (XPS). MUA and DT adsorb on the Fe surface by cathodization in the potential range corresponding to the hydrogen evolution reaction by forming thiolate bonds. The presence of the adsorbate layer in contact with an extremely low amount of thiols in the neutral solutions hinders the hydrogen evolution reaction and prevents the formation of the iron oxides in a wide potential range.     

Electrochemical corrosion behavior of hot-rolled steel under oxide scale in chloride solution

In this work, electrochemical corrosion behavior of a hot-rolled steel with oxide scale was investigated in chloride solution through electrochemical measurements and surface characterization. Results demonstrated that the presence of a layer of compact oxide scale would protect the underlying steel from corrosion attack. Upon immersion in chloride solution, oxide scale on the steel surface is reduced, resulting in increase of electrode activity and corrosion rate of the steel. With the further immersion, the insolvable corrosion product and/or new oxide form to accumulate on the electrode surface, enhancing the electrode resistance and decreasing the corrosion of the steel. The amount of dissolved oxygen affects the corrosion of steel. With the increasing concentration of oxygen, there is more compact corrosion product and/or new oxide generating on electrode surface.     

水质稳定剂TJ-401的合成及其缓蚀阻垢分散性能研究

以水为溶剂,采用过氧化物-次磷酸盐为引发体系,用马来酸酐(MA)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)、丙烯酸(AA)为单体在水相中合成了四元共聚物TJ-401水质稳定剂。讨论了单体配比、引发剂用量,反应温度等条件对产物缓蚀阻垢分散性能的影响．确定了TJ-401的合成工艺。结果表明：水质稳定剂TJ-401的性能较好,具有优异的阻碳酸钙垢、阻磷酸钙垢、分散三氧化二铁等阻垢分散性能及缓蚀性能,且阻碳酸钙垢性能和缓蚀性能优于TJ-301。     

Corrosion inhibition of mild steel by Calotropis procera leaves extract in a CO2 saturated sodium chloride solution

The Calotropis procera leaves extract (CPLE) was investigated as a corrosion inhibitor for mild steel in a CO₂-saturated 3.5 wt% NaCl solution using various electrochemical techniques. The results show that the CPLE is an effective inhibitor with inhibition efficiency of 80% using 50 ppm. Polarization studies show that the CPLE acts as a mixed inhibitor, and the adsorption of CPLE follows Langmuir adsorption isotherm. Molecular dynamics simulations reveal that the presence of N, O in the CPLE as well as π-electron systems coupled with high adsorption energies of interaction of the CPLE with steel are responsible for corrosion inhibition performance.     

模拟高矿化度矿井水阻垢缓蚀剂的研究

采用碳酸钙沉积法测定5种单一阻垢剂对CaCO3的阻垢效果,聚环氧琥珀酸（PESA）的最佳使用质量浓度为15mg／L时,其阻垢率达到75．3％;在含磷类阻垢剂中,2-膦酸基-1,2,4-三羧基丁烷（PBTCA）的最佳使用质量浓度为20mg／L时,其阻垢率达到76．1％。PESA与PBTCA的浓度比为10：15时,阻垢率可达94．2％。通过正交实验和平行实验,确定三元阻垢剂的最佳配比,即ρ（PESA）：ρ（PBTCA）：ρ（TS-623）（丙烯酸-AMPS三元共聚物）=8：12：8,阻垢率达到96．5％,阻垢效果最佳,且磷含量较低,价格合理,是较为理想的复配型阻垢剂。静态阻垢实验和中试规模的动态试验结果表明,本实验研究的阻垢缓蚀剂能完全适用于工业循环冷却水系统。     

磁处理器DAM防腐阻垢试验研究

上海石化股份有限公司环保中心湿式氧化装置的冷却塔和热交换器腐蚀结垢严重。为了解决此问题,作者对磁处理器DAM防腐阻垢的效果进行了研究,对DAM防腐阻垢机理进行初步探讨,并代替水处理剂进行了试验。试验结果表明：DAM除垢防腐效果明显,具有不增加水中其他离子,不引起二次污染和操作简便等优点。技术经济分析表明,循环流量为300t／h的小型循环冷却装置,用DAM处理,一年可节约14．1万元。磁处理的环境效益、经济效益和社会效益均显著。     

Effect of resistivity on the corrosion mechanism of mild steel in sodium sulfate solutions

Electrochemical impedance spectroscopy (EIS) was used to study the corrosion behavior of mild steel samples immersed in 1, 0.1, 0.01 and 0.001% Na₂SO₄ aqueous solutions at room temperature in order to analyze the corrosion mechanism and obtain representative values of corrosion rates in environments with different resistivity. The EIS technique was used to measure corrosion current densities in 1 to 0.01% Na₂SO₄ solutions, and the measurement corresponding to 0.001% concentration gave a scattered Nyquist plot, whereas in the Bode representation a response associated with solution resistance was obtained. Other electrochemical techniques such as linear polarization resistance, LPR, Tafel extrapolation method and electrochemical noise (EN) were used in order to compare the results obtained by EIS. The charge-transfer resistance (R _ct) parameters obtained in the EIS technique agree well with the corresponding values of polarization resistance (R _p) values obtained by the LPR technique, whereas the electrochemical noise resistance (R _n) parameters obtained by the EN technique gave the highest values for all concentrations. These parameters generally tended to increase as the concentration of the solution decreased.     

碳纤维在不同电解质体系下的电化学表面改性

使用电化学氧化法对PAN基碳纤维进行表面改性,通过扫描电子显微镜（SEM）、Raman光谱和X射线光电子能谱仪（XPS）表征了碳纤维表面物理化学结构,同时结合力学性能分析,评价了碳酸氢铵、硫酸铵和复合铵盐溶液3种电解质体系的改性效果。实验结果表明,碳酸氢铵溶液下的电化学改性有利于界面粘结强度的提高,而硫酸铵溶液下的电化学改性有利于降低抗拉伸强度的损失,当采用复合溶液改性时,则可以同时提高碳纤维的抗拉伸强度和其复合材料的抗层间剪切强度。