铁铬合金摩擦破损微电偶的形成及作用

本文分析，研究了１Ｃｒ１８合金材料在０．２ｍｏｌ．Ｌ＾１Ｈ２ＳＯ４溶液中的摩擦腐２蚀过程中产生微电偶腐蚀的可能性及原因，并研究了微电偶对摩擦电化学行为的影响，研究结果表明：由于摩擦过程造成材料表面的电化学不均一性是产生微电偶作用的真正原因。未摩擦表面与摩擦表面的面积比显著地影响了摩擦电偶电位和摩擦电偶电流的大小。     

钨的化学机械抛光过程中TiN-W电偶的腐蚀行为(英文)

化学机械抛光 (CMP)技术是同时利用化学和机械作用来获得固体表面亚微米尺度上平整性非常有效的方法 ,从 90年代初期起已成为制备高质量镜头和镜面及集成电路制造过程中硅片表面预处理工艺中最常用的技术之一 .钨的化学机械抛光是用钨坯获得硅片球面平整度的重要工艺 .其过程实际上是先将钨沉积到硅上已有的薄粘附层 -氮化钛上 ,然后进行化学机械抛光 .当抛光阶段接近终了时 ,氮化钛和钨表面将同时暴露在化学抛光液中形成电偶对 ,并在界面上发生腐蚀行为 ,从而影响硅片的球面平整度 ,降低半导体器件的性能与可靠性 .本文通过采用电化学直流极化技术 ,分别获得钨与氮化钛在 0 .0 1mol/LKNO3溶液中或含有三种典型的研磨剂 (H2 O2 ,KIO3,Fe(NO3) 3)溶液中的极化曲线 ,同时设计了一种特殊的电解槽以测量钨和氮化钛之间相互作用的电流 ,初步研究了 patterned硅片上钨和氮化钛界面形成电偶对时的腐蚀行为 .根据所测的钨和氮化钛电位可知 ,当钨和氮化钛表面同时暴露在抛光液中时将形成电偶对 ,氮化钛成为阴极 ,钨为阳极 ,并于界面发生电化学反应 ,表面的不均匀腐蚀将造成硅片平整度的降低 .结果表明 ,当溶液中含有H2 O2 时钨和氮化钛界面的腐蚀速度最大 ,而当溶液中含有Fe(NO3) 3时的钨和氮化钛界面则几乎不发     

丝束电极研究裂纹对混凝土中钢筋腐蚀的影响

应用丝束电极技术测量浸在10%NaC l溶液中的混凝土内铁丝束的自腐蚀电位和极化电阻分布,研究裂纹对混凝土中铁丝腐蚀的影响和乙醇胺的缓蚀作用.结果表明,裂纹加速了水、氧和氯离子向两侧混凝土中扩散,增加了铁丝腐蚀的不均匀性.乙醇胺扩散到混凝土中,吸附在铁丝表面,基本不改变铁丝的自腐蚀电位,但显著降低了铁丝腐蚀速率,有效抑制了裂纹引起的不均匀腐蚀.     

阵列微电极研究Nd~(3+)对金属铜在3.5% NaCl溶液中腐蚀电化学行为的影响

利用阵列微电极技术测量了金属铜的自腐蚀电位、阻抗及表面腐蚀产物膜层载流子密度,并结合扫描电子显微镜,研究了Nd3+对金属铜在3.5%(w)NaCl溶液中腐蚀电化学行为的影响.结果表明,加入Nd3+使得金属铜表面生成的腐蚀产物膜层的形貌及结构发生了变化,腐蚀产物膜层变薄,腐蚀产物由片状结构转变为粒状结构,颗粒均匀分散分布;Nd3+的存在使得金属铜表面各区域的电位方差由0.034下降为0.026,阻抗标准方差由32805下降为6940,电位及阻抗分布趋于均匀化,有利于抑制局部腐蚀的发生;并且加入Nd3+将造成金属铜表面绝大部分区域腐蚀产物膜层的半导体类型由n型转变为p型,表面腐蚀产物膜层载流子密度标准方差由1.89×1017上升为4.10×1017,载流子密度分布趋于不均匀.     

碳钢在NaNO_2-NaCl溶液中的电流波动

用动电位和恒电位极化法研究了A3碳钢在NaNO2＿NaCl溶液体系中的电流波动特征.A3钢在不含Cl-的0.1mol/LNaNO2溶液中能保持良好的钝态,当加入一定浓度的Cl-后,电流出现了明显的快速上升,再缓慢下降的波动特征,表明此时碳钢表面生成了溶解较快而再钝化相对较慢的亚稳态孔蚀.实验中可观察到因电流波动而产生的累积腐蚀损伤的蚀孔.实验表明,随着Cl-浓度的增加,出现亚稳态孔蚀的初始电位Em降低,相应的电流波动峰值增大,峰频增加;而升高电位,则电流波动的峰值和峰频也都增加,况且再钝化时间延长,由此可见电位的升高促进了亚稳态孔的溶解,并能激活更多的活性点使孔诱发速率增大.     

植入用Co—Cr—Mo合金与Ti—6Al—4V合金的电偶腐蚀研究

组件式设计常被用地人工髋关节，钴络钼合金（Ｃｏ－Ｃｒ－Ｍｏ）与钛合金（Ｔｉ－６Ａｌ－４Ｖ）的压配最常用，本文应用电化学方法研究了静态条件下两种合金的电偶腐蚀行为，浸泡实验表明，钴络钼合金为阳极，但电偶电流与其维钝电流相近，并无明显加速度腐蚀效应，钛合金为阴极，受到保护，失重及金相观察结果显示，在４５天的浸泡实验周期内，未发现腐蚀痕迹，混合电位理论和电位处于两种合金的钝化电位区，电偶电流为合金的维钝     

活性氯在316L不锈钢电极表面的阴极行为研究

利用电化学方法研究了活性氯在3.5%NaCl溶液中316L不锈钢电极表面的阴极还原反应及其反应机制.实验表明,随着溶液中活性氯浓度的增加,316L不锈钢的自腐蚀电位正移,阴极反应的极限扩散电流明显增大,说明活性氯对316L不锈钢电极表面的两个阴极反应,即HClO还原和ClO-还原具有明显的促进作用.本文的研究确定了产生这两个还原反应的电位范围,并进一步探索了该还原反应速度的控制步骤.     

硫酸根离子对铁在弱碱性溶液中阳极溶解和钝化行为的影响

采用浸泡实验, 电化学测试和表面分析技术研究了硫酸根离子浓度对铁在稀碳酸氢钠溶液中开路状态和阳极极化行为的影响. 在无硫酸根离子及含有少量硫酸根离子的碳酸氢钠溶液中, 铁的开路电位约为(-0.225±0.005) V, 并呈现钝化状态, 其电化学阻抗很大, 腐蚀速率较低. 在含有较高浓度硫酸根离子的碳酸氢钠溶液中, 铁的开路电位为(-0.790±0.010) V并呈现活性溶解状态, 其电化学阻抗较小, 腐蚀速率较高, 同时阳极极化曲线上能观察到活化-钝化转变现象. 由于铁在含有较高浓度硫酸根离子的碳酸氢钠溶液中处于活化状态, 阳极极化曲线上存在数个电流峰. 足够高的硫酸根离子浓度会导致铁表面预先形成或转变而成的氧化膜失效. 相比于自然曝氧状态, 在除氧条件下较低的硫酸根离子浓度即可引起铁在碳酸氢钠溶液中由钝态向活性溶解态的转变.     

超重力场电沉积NiW合金及其耐碱腐蚀性能

在超重力条件下电沉积NiW合金镀层,考察了超重力对NiW合金电沉积过程(各元素分电流、W含量和槽电压等)的影响规律;并利用扫描电子显微镜(SEM)、Tafel技术和电化学阻抗谱(EIS)技术研究了电沉积NiW合金镀层的表面形貌和在NaOH溶液中的抗腐蚀性能,同时通过浸泡实验考察了镀层的稳定性.结果发现,与常重力条件电沉积的NiW合金相比,超重力场电沉积的NiW合金中W含量增加,镀层表面无微裂纹产生;在10%(w)NaOH溶液中镀层自腐蚀电位正移,自腐蚀电流密度减小,腐蚀电阻也由常重力(重力系数G=1)时的865Ω·cm2增大至超重力(G=256)时的2305Ω·cm2;在10%NaOH溶液中浸泡144h后,超重力场电沉积的NiW合金表面无破碎和起皮现象发生.超重力技术在NiW合金电沉积过程中的应用,使镀层的耐碱腐蚀性能得到改善.     

扫描微电极法原位测量2024Al合金表面微区Cl~-浓度分布

应用自研制扫描微电极测量系统和扫描微Ag/AgCl复合电极 ,原位测量含Cl- 溶液中 ,2 0 2 4Al合金在其局部腐蚀发生发展过程中金属 /溶液界面微区Cl- 离子的浓度分布 ,考察金属 /溶液界面微区Cl- 浓度分布对Al合金表面局部腐蚀行为的影响 .结果表明 ,扫描Ag/AgCl探针可实时跟踪腐蚀过程中金属表面氯离子浓度分布的动态行为 .当 2 0 2 4Al合金浸渍于含Cl- 溶液中 ,Cl- 离子在Al合金 /溶液界面呈不均匀分布 ,Cl- 主要在第 2相颗粒和铝基交界区域发生优先吸附和累积 ,从而促进局部腐蚀的发生和发展     

碳钢缝隙内溶液化学和阳极极化行为研究

为研究缝隙腐蚀的溶液化学和缝中金属阳极极化行为,设计一种楔形缝隙模拟装置。以碳钢为研究对象,分别测试了在３．５％（ｗｔ）ＮａＣｌ溶液中缝内各位置的电极电位,Ｃｌ＾－浓度,ｐＨ值以及缝外阳极极化时电流密度的变化。     

应力对低合金钢焊接接头相电化学行为的影响

采用微区相电化学测试技术,测量和研究了１６Ｍｎ钢焊接接头上不同热经历区在硝酸盐溶液中的微区相电化学行为（包括自腐蚀电位、自腐蚀电流密度和极化曲线）以及外加载荷（应力）的影响。此外,还分别测量了各区中铁素体和珠光体的电化学行为,尤其是加载状态下的行为。结果表明,加载后各热经历区以及各区中铁素体和珠光体的自腐蚀电位均比未加载前负移,相应的自腐蚀电流密度增大,铁素体和珠光体之间电位差明显减小。加载后各热     

Low power electrocorrosion for sample preparation: identification of metals in alloys

Rapid surface oxidation of a metal was carried out using a low voltage (9-18 V dc) power supply to examine the feasibility of low power electrocorrosion as an alternative to current metal sampling techniques such as acid digestion. Potential was applied between a metal alloy and a cellulose electrode that was made conductive using an aqueous solution (NH₄NO₃, KCl). Metal ions diffuse into the cellulose as rapid surface oxidation of the metal occurs. The metal ions can then be extracted and analyzed using atomic spectroscopy (e.g. GFAAS). Steel (316L, SRM 663), brass and aluminum alloys were electro-corroded using constant potential. At short intervals (<2 min) the mass of corroded metal increased linearly with time. Corrosion rates for Cr, Ni, Cu and Mn ranged from 870 to 34 pg s⁻¹. The mass of metal corroded increased as applied potential/current increased and depends on the surface area of the cellulose-metal contact. Experiments showed that preferential metal corrosion does not occur in steel samples. SEM images show that there is a relatively large area (∼1 mm²) of homogenous corrosion and that the most damage occurs closest to the edge of filter paper/metal contact. Low power electrocorrosion was used to identify metals in a fork of unknown composition. Multiple techniques (GFAAS, FAAS and SN-ICP-MS) were used for analysis and it was found that Ag and Cu were the primary metals in the alloy, in a ratio of 3:1. Trace amounts of other metals (<1%) were found but not quantified.     

Electrodeposition of Zn–Mn alloys at high current densities from chloride electrolyte

The Zn–Mn alloy electrodeposition on a steel electrode in chloride electrolyte was investigated with the aim of obtaining deposits with as high as possible Mn percent. It was found that the deposition current density and concentration of Mn²⁺ ion in the chloride electrolyte significantly affect the Mn content in the alloy coating as well as the coating surface morphology. There was a transition from dendritic and spongy to smooth, bright, and amorphous structure of Zn–Mn deposits, when some critical deposition current density was reached, probably due to the metal oxyhydroxide inclusion in the coatings. Several plating additives were tested in order to decrease the hydroxide content and to improve surface appearance of the deposits. The 4-hydroxy-benzaldehyde was found to decrease oxygen and increase Mn percent in the coatings, and to significantly improve their surface morphology.     

聚吡咯/聚苯胺复合型导电聚合物防腐蚀性能

采用循环伏安法,在含吡咯和苯胺的0.3 mol/L草酸水溶液中制备了聚吡咯/聚苯胺(PPy/Pani)的复合型导电聚合膜。采用红外光谱、极化曲线、自腐蚀电位-时间曲线、扫描电子显微镜和电化学阻抗谱研究了共聚膜的防腐蚀性能。结果表明,在1 mol/L H2SO4中,PPy、Pani与不锈钢基体发生氧化还原反应,促进不锈钢表面发生钝化;当苯胺与吡咯浓度比为1∶3时,制备得到的复合型导电聚合膜所保护的不锈钢自腐蚀电流最小,自腐蚀电位最高,保护时间最长。PPy、Pani及其共聚膜在3.5%NaCl溶液中电化学阻抗谱表明,所制备的PPy、Pani及其共聚物膜与不锈钢基体发生氧化还原反应,使其表面钝化;当Cl-到达不锈钢表面时,破坏钝化膜导致不锈钢腐蚀。     

Electronic properties of Si surfaces and side reactions during electrochemical grafting of phenyl layers

The electrochemical grafting process of 4-nitrobenzene and 4-methoxybenzene (anisole) from diazonium salt solutions has been investigated in situ by monitoring the current density, the band bending, and the nonradiative surface recombination during grafting at different potentials and different concentrations of the diazonium salt in the solution. Ex situ infrared spectroscopic ellipsometry has been used to inspect the Si surface species before and after the grafting process. The band bending decreases with either increasing concentration of diazonium salt or when the redox potential of the diazonium compound (anisole) is nearer to the competing H+/H2 couple. The surface recombination increases at more cathodic potentials if an electron donor group is present at the phenyl ring (nitrobenzene) and vice versa for the electron acceptor group (anisole). The influence of side reactions can be reduced by use of moderate concentration and moderate or strong cathodic potential, depending on the redox potential of the diazonium compound.     

Uranium association with corroding carbon steel surfaces

We investigated the association of uranium with clean and corroded surfaces of 1010 carbon steel. Studying steel contaminated by uranium species will have an important effect on the development of methods used to clean radioactively contaminated metal waste. X‐ray photoelectron spectroscopy, synchrotron infrared microspectroscopy and laboratory‐based Fourier transform infrared analysis of steel surfaces exposed to uranyl nitrate showed the presence of crystallized hydrated uranyl oxides, uranyl hydroxides, iron oxyhydroxides and iron oxides. In general, heavily corroded areas physically shield the uranium species, which tended to associate spatially with hydroxyl groups and lepidocrocite. Lightly corroded areas contained uranium species with stronger axial U–O bonding. Infrared spectroscopy, Rutherford backscattering spectroscopy and energy‐dispersive spectroscopy mapping analysis revealed that the uranium species are well distributed within the upper micron of the thick corrosion layer and associated more with areas of high hydroxide content. Parameters such as the concentration of uranyl nitrate solution used to expose the carbon steel coupons, the method of contamination (dipped or sprayed with dilute uranyl nitrate solution) and the degree of corrosion (accelerated corrosion before and/or after contamination) played significant roles in the distribution and nature of the uranyl hydroxide/iron oxyhydroxide corrosion products found on the surface of all coupons. These factors must be considered in the development and optimization of decontamination processes for metal waste. Copyright © 2003 John Wiley & Sons, Ltd.     

Spectroscopic study of decontaminated corroded carbon steel surfaces

Removal of uranium from contaminated carbon steel surfaces by chelation with hydroxycarboxylic acid has been tested as a cleaning process for decommissioning and decontaminating contaminated surfaces. Comparison of contaminated surfaces prior to decontamination with subsequently cleaned surfaces was done in order to study the effectiveness of this cleaning technique. This was accomplished using various spectroscopic techniques, including x‐ray photoelectron spectroscopy, synchrotron infrared microspectroscopy, Rutherford backscattering spectroscopy and scanning electron microscopy/energy‐dispersive spectroscopy. Mild carbon steel (1010) coupons were exposed to uranyl nitrate solution, which led to the formation of a lightly corroded surface. Some contaminated samples underwent further cyclic humidity treatment, during which additional corrosion took place. In this study, it was found that a citric acid–hydrogen peroxide–citric acid cleaning method successfully removed uranium in lightly corroded areas. However, the method but incompletely decontaminated some heavily corroded areas where more highly crystallized corrosion products are found or where complex surface structure can occlude contaminants. Use of complementary analytical techniques is essential to provide an accurate model of surface chemistry before and after decontamination. Copyright © 2004 John Wiley & Sons, Ltd.     

Mn2+浓度对钒液流电池正极液的电化学性能影响

电解液中金属离子会影响钒液流电池的电化学性能。本文采用循环伏安法和电化学阻抗谱研究了正极液中Mn2+浓度对V髨/V(Ⅳ)电对的氧化还原过程影响规律,发现Mn2+在正极液中没有发生副反应,但严重影响V髨/V(Ⅳ)的反应活性、电极反应可逆性、离子扩散与电荷转移反应等电化学性能。循环伏安测试结果表明Mn2+浓度为0.04-0.13 g.L-1时,V髨/V(Ⅳ)电对电极反应可逆性和反应活性较高,钒离子扩散系数由参照溶液中的8.89×10-7-1.098×10-6增大至1.302×10-6-1.800×10-6 cm2.s-1,提高了-60%;电化学阻抗测试结果表明Mn2+浓度为0-0.04 g.L-1时,V髨/V(Ⅳ)电对电极反应阻抗和界面阻抗均较参照溶液中的增加不明显,但当Mn2+浓度增至0.07 g.L-1时,上述阻抗值较参照溶液增大了25%-28%。基于二者结果,Mn2+对电极反应有不同程度的负面影响,但是适当的Mn2+浓度有利于钒离子的扩散。     

Use of scanning reference electrode technique for characterizing pitting and general corrosion of carbon steel in neutral media

The scanning reference electrode technique (SRET) was used to characterize the corrosion behavior of carbon steel in the NaNO₂-containing chloride solution and tap water. In 10⁻³ MNaNO₂+10⁻³ MNaCl+10⁻³ MNa₂SO₄ solution, the passivated carbon steel surface suffered the pitting. In this case, the size of anodic and cathodic areas on the corroding surface varied with the exposed time, but anodic and cathodic sites did not change. On the contrary, the carbon steel was corroded generally in the tap water. The localized anodes and cathodes on the corroding surface were not fixed but movable with the exposed time during the whole corrosion process, and the “movable anodes” can be in situ monitored and momentarily identified by SRET measurements.