工业纯Al的缝隙腐蚀再钝化电位

工业纯Ａｌ的缝隙腐蚀再钝再钝化电位ＥＲ是缝隙结构的特征值，与缝隙腐蚀下限电位ＶＣＲＥＶ一致，比孔蚀电位负约１００ｍＶ，说明缝隙腐蚀最易发生。     

合金元素铁对钛缝隙腐蚀性能的影响

用浸泡腐蚀试验及电化学测试技术研究了合金元素铁对钛抗缝隙腐蚀性能的影响。试验结果表明,加入铁使缝隙腐蚀再钝化电位ＥＲ变负,缝隙腐蚀诱导期缩短,腐蚀率增大。通过电子探针分析和ＳＥＭ观察发现,铁以ＴｉＦｅ形式在晶界析出,腐蚀优先在ＴｉＦｅ析出物上发生,并且沿晶界向内部发展。由此得知,缝隙腐蚀起源于ＴｉＦｅ析出物,继而成长并促进了缝内活性溶解。     

防锈油膜失效之前的电位变化

采用丝束电极研究防锈油膜失效之前的电位变化,结果表明,防锈油膜失效之前,涂油丝束电极腐蚀电位在（－０．２￣０．３Ｖ ｖｓ ＳＣＥ）范围内分布,呈现一定程度的不均匀性,防锈油膜失效之前,涂油丝束电极腐蚀电位随着浸泡时间而发生变化,在浸泡初期,随着浸泡时间的延长,腐蚀电位分布发生一定程度的正移,当腐蚀电位分布达到最大值时,随着浸泡时间的延长,腐蚀电位开始发生负移。防锈油膜失效之前,涂油丝束电极腐蚀电位     

对45#钢管道的缝隙腐蚀模拟研究

目的预测埋地金属管道缝隙表面电位分布和腐蚀速度。方法造金属管道缝隙腐蚀的几何模型,对腐蚀管道采取阴极保护,推导腐蚀管道的电化学反应动力方程式。对几何仿真模型的初始条件及边界条件进行约束,采用MATLAB软件对阴极保护电位分布规律和表面缝隙腐蚀速度的几何模型进行了仿真,并且与实验测量结果进行对比,得出了仿真结果与实验结果的相对误差。结果采用阴极保护金属管道表面缝隙腐蚀的底部仿真电位随时间的增加而反向增大,在极化时间50 h内最大电位为-8.6 V。采用阴极保护金属管道表面缝隙腐蚀的仿真电位随缝隙深度的增加而反向减小,在距离缝隙表面10 cm内最小值为-0.78 V。采用阴极保护金属管道表面缝隙的仿真腐蚀速度随时间的增加而逐渐减小,在前5年内腐蚀速度最小值达到0.334 mm/a。同时,电位分布和腐蚀速度的仿真值与实验测量值的相对误差在5%以内,误差较小。结论采用矩形缝隙模型可以近似预测阴极保护的电位分布和缝隙表面腐蚀速度,从而降低了金属管道腐蚀速度,避免了金属管道发生灾难性的事故。     

C15不锈钢在3.5%NaCl溶液中的耐蚀性

用电化学方法研究了C15不锈钢的点蚀电位和缝隙腐蚀行为。结果表明:在30℃的3.5%NaCl溶液中,C15不锈钢的自腐蚀电位和点蚀电位均高于对比材料316L和1Cr18Ni9Ti不锈钢的;C15不锈钢缝隙试验用试样在施加0.8V(SCE)恒电位条件下不发生腐蚀。     

慢应变速率下0.8PVRe钢在10%NH4NO3溶液中应力腐蚀开裂的研究

用慢应变速率拉伸试验方法研究了０８ＰＶＲｅ钢在１０％ＮＨ３ＮＯ３溶液中几种外加极化电位下的应力腐蚀开裂敏感性，结果表明：０．８ＰＶＲｅ钢在１０％ＮＨ４ＮＯ３溶液中，在一定的电位范围内会发生沿晶应力腐蚀开裂，在＋１３４ｍＶ和＋１４５ｍＶ下的敏感性最强。用断裂力学，电化学以及金属物理的基本知识对材料发和沿晶应力腐蚀开裂的机理进行了分析讨论。     

夹层体的电偶腐蚀

对夹层体在腐蚀条件下的电偶腐蚀行为进行了研究。根据复变函数理论求出了夹层结构表面腐蚀电流和电位的分布的表达式。利用SMRE技术测定了带裂纹的夹层体表面的电位分布,讨论了夹层体表面腐蚀电位的不均匀分布现象,分析了夹层体电偶腐蚀和缝隙腐蚀之间的互作用。     

衣康酸介质中Cl^—和NO3^—对不锈钢点蚀电位的影响

利用动电位法测定３１６Ｌ奥氏体不锈钢和Ｒ１双相不锈钢在Ｃ５Ｈ６Ｏ４－Ｃｌ＾－－ＮＯ３＾－水溶液体系中的阳极极化曲线和点蚀电位,探讨了衣康酸（Ｃ５Ｈ６Ｏ４）介质中Ｃｌ＾－和ＮＯ３＾－对点蚀的影响。结果表明：（１）Ｃｌ＾－浓度［Ｃｌ＾－］的提高导致不锈钢点蚀电位Ｅｂ降低,其关系为Ｅｂ＝ａ－ｂｌｇ［Ｃｌ＾－］。同样条件下,Ｒ１不锈钢的点蚀电位比３１６Ｌ不锈钢高３００￣４００ｍＶ;（２）在含Ｃｌ＾－的衣康     

CREVICE CORROSION BEHAVIOR OF THE STEEL X70 UNDER CATHODIC POLARIZATION

采用矩形缝隙装置, 测量了模拟剥离涂层下不同位置X70钢的电位、溶液pH值及氧含量随时间的变化曲线. 研究了外加阴极极化电位、涂层破损尺寸和缝隙厚度对X70钢在Na2SO4溶液中的缝隙腐蚀行为的影响. 结果表明, 缝隙内氧气迅速耗尽并使溶液pH值升高, 氧耗尽与外加阴极极化电位无关. 随着缝口阴极极化程度加大, 缝隙内各点电位负移, 有效保护距离增加. 溶液介质电位(IR)降集中在缝口. 极化程度过高会导致氢气的析出. 减小缝隙厚度和破损点尺寸使缝隙内极化程度降低.     

阴极极化条件下X70钢的缝隙腐蚀行为

采用矩形缝隙装置,测量了模拟剥离涂层下不同位置X70钢的电位、溶液pH值及氧含量随时间的变化曲线．研究了外加阴极极化电位、涂层破损尺寸和缝隙厚度对X70钢在Nu2SO4溶液中的缝隙腐蚀行为的影响．结果表明,缝隙内氧气迅速耗尽并使溶液pH值升高,氧耗尽与外加阴极极化电位无关．随着缝口阴极极化程度加大,缝隙内各点电位负移,有效保护距离增加．溶液介质电位（IR）降集中在缝口．极化程度过高会导致氢气的析出．减小缝隙厚度和破损点尺寸使缝隙内极化程度降低．     

模拟体液中纯钛及Ti6A14V合金的腐蚀行为

采用电化学测试技术研究了人体医用金属材料工业纯钛和Ti6A14V合金在人工模拟体液中的腐蚀行为,结果表明,阳极极化后两种合金均未发现点蚀,工业纯钛的维钝电流密度小于于Ti6A14V合金,前者的阳极极化性能优于后者,Ti6A14V合金缝隙试样在阳极电位超过＋2000mV(vsSCE)后,电流开始急剧增大,发生了缝隙腐蚀;通过电子探针分析发现,在缝隙内Al和V两种元素发生活性溶解。工业纯钛在电位达到＋4000mV/(vsSCE）时仍没有发生缝隙腐蚀。     

钛的缝隙腐蚀行为研究

采用电化学测试技术，研究了工业纯钛和Ｔｉ－０．３％Ｍｏ－０．８％Ｎｉ合金在２５％ＮａＣｌ和ＨＣｌ沸腾溶液中的缝隙腐蚀行为。结果表明，由于合金元素Ｎｉ具有低的氢超电势，促进了阴极极化过程，从而提高了钝化能力，且缝内表面Ｎｉ的富集增强了膜的钝化稳定性，因此，Ｔｉ－０．３％Ｍｏ－０．８％Ｎｉ合金抗缝隙腐蚀性能优于工业纯钛。     

Rauschuntersuchungen zur Spaltkorrosion

Noise measurements on crevice corrosion The importance of Al‐Mg‐Si‐alloys as an alternative to Al‐Cu‐Mg‐alloys has continuously increased in aircraft industry over the recent years. Al‐Mg‐Si‐alloys are corrosion resistant under normal atmospheric conditions. However localised corrosion, especially crevice corrosion, can be very dangerous. Pitting or crevice corrosion can be divided into an initial state and a propagation state of corrosion. The transition of a corrosion system from the passive state into the initial state of localized corrosion is characterised by the small fluctuation of the current and the potential. The measurement of this fluctuation is the subject of the electrochemical noise analysis (ENA). Therefore ENA leads to extensive knowledge about the activity of the corrosion system already in the pre‐damaged state. With the help of ENA the influence of crevice condition, potential and time on the initial state of the crevice corrosion on AA 6013 can be demonstrated.     

离子注入Cr、Mo、Al对碳钢缝隙腐蚀行为的影响

采用电化学测试技术研究了离子注入Cr、Mo、Al对碳钢在海水中缝隙腐蚀行为的影响。结果表明,Cr、Mo复合离子注入表面降低缝隙腐蚀率,提高ER,显著改善了耐缝隙腐蚀性能,该效果优于Cr离子单独注入表面。Al离子注入表面使ER变负,耐缝隙腐蚀性能变劣。     

Numerical simulations study of the localized corrosion resistance of AISI 316L stainless steel and pure titanium in a simulated body fluid environment

The resistance of both AISI 316L stainless steel (AISI 316L SS) and commercially pure titanium (cpTi) to localized corrosion in a simulated body fluid solution was investigated using numerical simulations. The resulting model, based on transport equations in dilute solutions, is designed to predict the susceptibility of these two biomaterials to crevice corrosion initiation. The results show that cpTi and AISI 316L SS alloy are very resistant to the initiation of crevice corrosion in 0.9% NaCl solution and AISI 316L SS alloy is more susceptible to corrosion initiation over the long term than cpTi.     

The role of electrolyte concentration on crevice corrosion of pure nickel

In this work an artificial crevice electrode was used in conjunction with a fine microprobe assembly to measure the potential inside the crevice. Using this setup crevice corrosion of commercially pure nickel was investigated in sulfuric acid with concentrations: 0.5, 1 and 2N. The outer surface of the Ni was held at a passive potential of 530 mV(SCE) while the experiment was running. The results showed a steep potential decay observed in all concentrations. For 0.5, 1 and 2N H₂SO₄, the total potential drop inside the crevice was: 681, 619 and 593 mV, respectively. This indicates the higher the acid concentration is the lower the potential drop will be. On the other hand, the measured current was highest (4.09 mA) for 2N and lowest (1 mA) for 0.5N. On the crevice wall a boundary was found to exist between the passive and the active regions. These findings point toward the IR voltage drop mechanism operating for this system.     

SiCp/2024Al基复合材料的点蚀行为

采用动电位阳极极化法对17%SiCp/2024Al基复合材料及其基体合金在3.5%NaCl水溶液中的耐蚀性进行了研究.结果表明:SiC颗粒的加入并不影响SiCp/2024Al基复合材料的点蚀敏感性,但与基体相比,其耐蚀性有所下降.对极化后和长期浸泡试样的腐蚀形貌观察发现:与基体相比,SiCp/2024Al基复合材料表面上的蚀孔数量相对较多,蚀孔尺寸稍小,大小分布不均匀;最大蚀孔较深,并有严重的裂缝腐蚀;裂缝腐蚀的存在会使SiCp/2024Al基复合材料的点蚀抗力明显降低.能谱分析表明:SiCp/2024Al基复合材料的腐蚀机制为富Cu阴极相与贫Cu阳极相间的电偶腐蚀,另外,SiC与Al间也存在电偶腐蚀倾向.     

Crevice corrosion monitoring of titanium and its alloys using microelectrodes

Crevice corrosion of titanium and its alloys in 10% sodium chloride was investigated at 100°C with the aid of microelectrodes. Potential, pH and chloride ion concentration inside the crevice were monitored using an Ag/AgCl electrode, a tungsten microelectrode and a Ag/AgCl chloride ion selective microelectrode, respectively. The pH and Cl^? concentrations within the crevice were calculated from the standard potential‐pH and potential‐log[Cl^?] calibration curves. The effect of Mo on the crevice corrosion of titanium was also studied. The passivation behavior on the titanium and Ti‐15%Mo alloy was studied using electrochemical impedance studies. There was no apparent change in pH and Cl^? ion activity inside the crevice for the alloy at 100°C, whereas a marginal decrease in pH and increase in Cl^? ion concentration were observed for pure titanium. Thus pure titanium is susceptible to crevice corrosion in hot 10% NaCl solutions at 100°C. The chloride ion activity was found to be reduced for the alloy so that the pH inside the crevice increased. The corrosion reaction resistance (R_t) was found to increase with the addition of Mo as an alloying element. It also increases with externally applied anodic potential. Hence, Mo is an effective alloying element, which enhances the crevice corrosion resistance of titanium.     

用丝束电极研究SO_4~(2-)对纯铝缝隙腐蚀的影响

采用动电位极化和丝束电极技术测量了纯铝在2mol/L NaCl和2mol/L NaCl 0.8mol/L Na2SO4溶液中的极化曲线、缝隙内外的自腐蚀电位和电化学阻抗分布,研究了SO42-对铝缝隙腐蚀的影响。结果表明,在NaCl溶液中,缝隙内的铝为阳极、缝隙外为阴极;随浸泡时间增加,腐蚀不均匀性增加。加入Na2SO4后,减小了缝隙内外腐蚀电位差,显著降低了铝的腐蚀速度。Na2SO4是中性溶液中铝的吸附型缓蚀剂,延缓了缝隙腐蚀的发生。