运用材料学方法确定阴极保护下限电位值

运用材料学方法，结合电化学测量，确定１６Ｍｎ钢－３％ＮａＣｌ水溶液体系在受力作用时阴极保护下限电位值为－９００ｍＶ（ｖｓ．ＳＣＥ）。若阴极保护电位比该值更负时，将会产生氢脆的危险。     

无氰电镀镉-钛合金对钢基体氢脆性能的影响

研究了无氰电镀镉-钛合金工艺对A100钢基体氢脆性能的影响,分别采用测氢仪法、氢含量测定法、恒载荷持久拉伸及慢拉伸的方法对A100钢基体电镀镉-钛合金氢脆性进行评价.结果表明:A100钢具有较低的氢脆敏感性,电镀镉-钛合金后氢大部分存在于镀层中,基体中氢含量较低;采用慢拉伸试验可以评价A100钢电镀镉-钛合金工艺的氢脆...     

40Cr钢的氢脆断裂特征的研究

本文应用断裂力学试验和SSRT试验研究了40Cr钢的氢脆断裂特性,结果表明:40Cr钢的K_(IC)=115MPa.m~(1/2),K_(IH)=20.4MPa.m~(1/2);应变速率3.3×10~(-6)—5.5×10~(-8)·s~(-1)范围,40Cr钢具有最大的氢脆敏感性。     

阴极保护和缓蚀剂技术联合保护成膜的表面分析研究

本文用能量色散谱仪 ( EDS)测定在缓蚀剂溶液中受到阴极保护的 90 7A钢表面的成分和使用扫描电镜 ( SEM)分析其表面显微结构 ;利用俄歇电子能谱 ( AES)分析90 7A钢表面成膜后 ,膜层的成分及成分沿深度的变化。通过分析阴极保护对缓蚀剂膜层的成分沿深度变化的影响 ,推测其成膜机理 ,研究阴极保护对缓蚀剂成膜结构的影响及其缓蚀机理。结果表明缓蚀剂和阴极电位对表面成膜有协同作用 ,从而能够解释缓蚀剂和阴极保护联合保护比单独用阴极保护效果好。     

电沉积Zn-Fe合金的渗氢行为研究

用双电解池测氢法研究氯化物镀液体系中电沉积Zn-Fe合金过程中的渗氢行为.结果表明:在所考察的工艺参数中,镀液pH值对渗氢电流的影响最大.用慢应变速率拉伸试验法(SSRT)考察了电镀Zn-Fe合金试样的氢脆特性,并用扫描电子显微镜(SEM)对断口的微观形貌进行了表征.所有Zn-Fe合金镀层的试样均显示出不同程度的氢脆敏感性.     

铵明矾在NH_4Al(SO_4)_2·12H_2O+NaCl+H_2O体系中溶解度的测定及关联

以铵明矾结晶法从含有氯化钠的废水中同时回收Al~(3+),NH_4~+和SO_4~(2-)离子,需要铵明矾在不同浓度氯化钠水溶液中的溶解度数据。文中采用静态法测定了铵明矾在283.15—323.15 K范围、氯化钠浓度为0—1.71 mol/kg水溶液中的溶解度。用Apelblat方程和λh方程对铵明矾溶解度实验数据进行了关联。实验表明:铵明矾溶解度随着温度升高而增大;随氯化钠质量摩尔浓度的增加而增大,盐溶效应明显。Apelblat方程和λh方程对铵明矾在氯化钠水溶液中溶解度的关联效果良好,相关系数R~2均大于0.999。采用冷却结晶法可以从含有氯化钠的废水中回收得到铵明矾;Apelblat方程和λh方程可用于关联氯化钠浓度为0—1.71 mol/kg范围内铵明矾的溶解度。     

电化学法研究钼系缓蚀剂

本文用动电位慢扫描法研究了钼系缓蚀剂在去离子水中和含 5ppm Cl-的去离子水中对 A3 钢的缓蚀性能 ,并与 2 0 0 ppm K2 Cr O4 在去离子水中和含 5ppm Cl-的去离子水中对 A3 钢的缓蚀性能作了比较。     

316L钢在含H_2S、Cl~-水溶液中的慢应变速率腐蚀试验研究

通过慢应变速率法 (SSRT)应力腐蚀试验 ,得到了 31 6L钢的应力腐蚀敏感性指数 ,回归出计算应力腐蚀敏感性指数的方程 ,表明水溶液中Cl- 对 31 6L钢的应力腐蚀影响较大 ,而H2 S的影响小。     

甲基丙烯酸六氟异丙酯酸度测定方法的研究

甲基丙烯酸六氟异丙酯(HFIP-M)是一种无色透明液体,酸度对其质量有重要影响。通过实验探索了甲基丙烯酸六氟异丙酯酸度的测定方法,采用了3种常用的方法测定酸度:1)用电位法指示滴定终点,滴定中采用自动电位滴定仪;2)用指示剂目测滴定终点;3)先用水或饱和氯化钠水溶液将试样中的酸萃取入水相,然后用碱滴定法在水溶液中测定其酸度。对比上述3种方法,结果表明:方法 1其滴定曲线突跃明显,且很好地避免了手动滴定时终点判断误差;用方法 2试验的3种指示剂中甲基红在滴定终点有较明显的颜色变化,且结果与电位滴定法测定的结果吻合;方法 3经试验表明,采用饱和氯化钠溶液作萃取剂,能明显改善分离效果,但经分离后的测定结果偏低,且此方法操作过程长而繁琐。     

地下管道阴极保护效果判断方法的改进

消除管地电位测量时IR降的干扰,修正其引起的偏差是正确评价地下管道阴极保护效果的前提.选择有代表性的典型管段和土壤环境条件,用试片断电法测取在最大保护电位下的实际IR降,并合理增加一定的余量后,作为所有地面测取读数所含的偏差.以行标规定的管地电位边界值(-850mV)与这一偏差的代数和作为判断管段阴极保护状态的地面测取读数判据,判断管道的阴极保护效果,是满足生产管理和工程验收的简便可行的方法.     

An electrochemical study of cathodic protection of steel used for marine structures

Impressed current cathodic protection can result in hydrogen embrittlement, which can cause trouble with high-strength steels, particularly at welds. Therefore, the limiting potential for hydrogen embrittlement should be examined in detail as a function of the cathodic protection potential. This study investigated the effects of post-weld heat treatment (PWHT) on marine structural steels from an electrochemical viewpoint. In addition, the slow strain rate test (SSRT) was used to investigate both the electrochemical and mechanical effects of PWHT on impressed current cathodic protection. According to the SSRT, the optimum cathodic protection potential was −770 mV [with a saturated calomel electrode (SCE)]. SEM fractography analysis showed that the fracture morphology at an applied cathodic protection potential of −770–850 mV (SCE) was a dimpled pattern with ductile fractures, while a transgranular pattern was seen at potentials below −875 mV (SCE). Therefore, the cathodic protection potential range should be −770–850 mV (SCE).     

Corrosion inhibition of steel by thiourea and cations under incomplete cathodic protection in a 3.5% NaCl solution and seawater

This study investigates corrosion inhibition of steel using thiourea and cations such as aluminium, calcium and magnesium under cathodic control in a 3.5% NaCl solution and in seawater. Steel protection in a 3.5% NaCl solution is normally incomplete under a cathodic potential less electronegative than –1.100 V. However, the protection can be enhanced by nearly 50% by adding either 50 ppm aluminium ion or 75 ppm thiourea in solution, and by almost 90% by the combined use of these additions. This study also analyzes how combining inhibitors and cathodic control may be used to protect steel. Moreover, this investigation monitors pH in the solution, measures zero-resistance current between the graphite-steel couple, as well as analyses cathode reaction products. A mechanism is also proposed to interpret the combined effects of inhibitors and cathodic control on the protection of steel.     

16Mn钢的氢渗透(Ⅱ)——表观氢扩散系数积分微分算法的验证及氢渗透对氢脆敏感性的影响

用电化学方法研究16Mn钢的氢渗透行为。结果表明,表观氢扩散系数的积分微分算法简便易行,适用范围广;塑性变形既能捕获氢,又可将捕获的氢释放,但使表观氢扩散系数减小;正火加回火态16Mn钢的抗氢脆性能的改善与其氢扩散活化能的降低,表观氢扩散系数的增大相对应。     

阴极极化对局部腐蚀闭塞区化学和电化学状态的影响

采用恒电流模拟闭塞电池装置研究阴极保护对局部腐蚀扩展阶段闭塞区化学和电化学状态之影响。对lCr13和0Cr18Ni9不锈钢-0.5mol/L NaCl溶液体系,发现阴极极化均使闭塞区溶液的pH值从各自的临界pH以下上升到临界值以上;Cl~-闭塞区向外电迁移;闭塞区的电极电位负移,可从电位-pH图上的“腐蚀区”降至“免蚀区”。由此可解释阴极保护抑制蚀孔或裂纹扩展的机理。     

Behaviour of Al-Sn alloy on the negative side of the open-circuit potential

The influence of the addition of small quantities of tin to high-purity aluminium (99.999%) on its electrochemical behaviour at high cathodic potentials was investigated. Cathodic current-time transients were recorded on Al-Sn alloys immersed in neutral 2m NaCl, when subjected to a potential pulse from a potential around the open-circuit potential to different negative values. Hydration of the oxide layer occurs at potentials more negative than –1600 mV vs SCE (for alloys with 0.02% and 0.09% Sn), –1750 mV (Al–0.2% Sn) and –1900 mV (Al–0.4% Sn), whereupon hydrogen is evolved at the metal-hydrated oxide interface. Anodic current responses to the return of the potential to the rest values were also recorded, and the charges required for oxidation of the substances created during the cathodic processes are discussed.     

The influence of thin benzoate-doped polyaniline coatings on corrosion protection of mild steel in different environments

The corrosion process of mild steel in the presence of benzoate-doped polyaniline coatings exposed to different environments (3% NaCl, atmosphere, and the Sahara sand) has been investigated. This system was also tested for cathodic protection and it has proven more efficient comparing to mild steel alone. Possible mechanisms of the corrosion protection of mild steel in the presence of a polyaniline-based coating in different corrosion media were also proposed.     

Electrochemical noise analysis of cathodically polarised AISI 4140 steel. II. Identification of potential fluctuation sources for unstressed electrodes

In this second part of the study of electrochemical noise (EN) generated by hydrogen evolution on a vertical cylindrical AISI 4140 steel electrode under galvanostatic control in 0.5 M sulphuric acid, the potential fluctuations induced by the growth and detachment of hydrogen bubbles at the electrode surface were analysed. They could be related to fluctuations of various quantities: electrode active surface due to bubble screening effects, concentration of dissolved hydrogen in the electrolyte close to the electrode surface, and metal-hydrogen interactions (MHI) on or beneath the electrode surface. The existence of MHI and their influence on faradaic potential fluctuations could be revealed by comparing the noise features on steel and platinum. The influence on EN of the charging cathodic current density, the presence of dissolved oxygen in the solution, and the electrode rotation speed was investigated in the absence of stress applied to the electrode. In the third paper of this series, the effect of hydrogen embrittlement on potential fluctuations of stressed electrodes will be examined.     

钢样在磷酸钠溶液中氯离子存在的极化曲线与腐蚀曲线

<正> 分析极化曲线的特微成功地探测金属在溶液中进行的腐蚀过程.把阳极极化曲线的直线部分延长到对应静电位的电流密度以代表自发腐蚀的阳极电流密度,同样得到阴级电流密度.认为阴极极化曲线和阳极极化曲线的直线部分的延是线交点,在近似情况,可代表自发腐蚀的溶解初速度.     

Electrochemical and anticorrosion performances of zinc-rich and polyaniline powder coatings

In this work, hydrochloride polyaniline (PANI-Cl) powder was incorporated as a conductive pigment into powder zinc-rich primer (ZRP) formulations in order to enhance the electronic conduction paths between zinc particles inside the coating and the steel substrate (i.e. percolation). Coatings were applied onto steel substrates and immersed in a 3% NaCl solution at ambient temperature.The protective properties and electrochemical behaviour of coatings were investigated by monitoring the free corrosion potential versus time and by using EIS. It was found that corrosion potential remains cathodic and constant for a long time up to 100 days of immersion. From EIS results, it was shown that the coatings exhibit larger impedance values than those observed with liquid or other zinc-rich powder formulations containing carbon black. From Raman spectroscopy results, it may be proposed that zinc particles in contact with PANI-Cl pigments were passivated. Other zinc particles remain still active which ensures the cathodic protection of the substrate. Moreover, coatings exhibit good barrier properties.