模拟混凝土孔溶液中钢筋钝化膜的光电化学方法研究

利用光电化学方法研究了钢筋在模拟混凝土孔溶液中钝化膜的电子性质，结果表明，钢筋在该溶液中形成的钝化膜是一种无定形的ｎ－型半导体成相膜，膜由多种铁氧化物组成，其组成受溶液中的离子、ＰＨ值、成膜电位影响，腐蚀抑制ＮａＮＯ２影响钝化膜的组成和生长过程，从而提高钢筋的抗氯离子点蚀能力。     

纤维素基磁性聚偕胺肟树脂研究：HAuCl4在树脂上的吸附与还原

研究了ＨＡｕＣｌ４在碱式纤维素基磁性聚偕胺肟树脂上的吸附动力学。吸附容量与吸附时间关系在初吸附的３０ｍｉｎ内可表示为Ｑ＝０．６４ｔ＾０．４。粒内扩散是吸附速度的控制阶段。在吸附过程中，同时发生氧化还原反应，Ａｕ（０）以不同聚集态附着在树脂表面。     

中性介质中铜缓蚀剂的成膜过程

使用光电化学与电化学石英晶体微天平联用（PECQCM）技术对中性介质铜缓蚀剂成膜过程进行了现场研究．结果表明，在中性Na2SO4溶液中钝化型缓蚀剂Na2OrO4对Cu成膜生长有抛物线规律，而由于Cl-的影响，在中性NaCl溶液中，该缓蚀剂膜生长曲线为折线型．沉淀型缓蚀剂Na2SiO3在Na2SO4溶液中的铜晶振电极上不成膜，而在NaCl溶液中可成膜．     

不锈钢上紫红色钼酸盐转化膜的研究

用阴极电沉积法从钼酸盐和磷酸盐混合溶液中获得了紫红色不锈钢转化膜，该膜具有良好的热稳定性。ＸＰＳ和ＡＥＳ分析表明，膜厚约９４．４ｎｍ。钼在膜表面以Ｍｏ（Ⅵ）存在，在膜内则以Ｍｏ（Ⅵ）和Ｍｏ（Ⅳ）共存。从ＡＥＳ深度剥蚀曲线的组成恒定区求得膜的组成为：Ｏ５４．８％，Ｍｏ３０．５％，Ｐ１１．２％和Ｆｅ３．５％，循环伏安的氧化峰也证明膜内存在Ｍｏ（Ⅳ）。     

钽在无水乙醇中的腐蚀

采用动电位极化、循环伏安、交流阻抗和扫描电镜等技术研究了钽在四乙基氯化铵（TEA）乙醇溶液中的腐蚀行为．在循环伏安曲线的扫描初期,电极表面因存在一薄层氧化物膜而使得电流密度缓慢增加．后来钝化膜因受到氯离子的攻击而被击穿,即点蚀．扫描电镜图很好地显示出蚀孔的生长过程．点蚀电位随着TEA浓度的增加而下降,随着水含量的增加而上升．在所研究的温度范围内,电化学反应的活化能为36kJ／mol．所有电极电位下的交流阻抗图谱都包含两个时间常数,钝化膜电阻和电荷传递电阻均随电极电位的增加而下降．     

在弱碱性及中性介质中AISI304不锈钢载波钝化膜光电化学研究

采用光电化学方法－恒电位光电流测量技术研究了ＡＩＳＩ３０４不锈钢在０．１ｍｏｌ／ＬＮａ２Ｂ４Ｏ７及０．５ｍｏｌ／ＬＮａ２ＳＯ４介质中载波钝化膜，光电流测量结果表明，光电流大小与电极电势、成膜条件及测量介质有关，载波钝化膜基本上是高度无序的非晶态膜。     

Keggin型杂多酸在镀锌钝化中的应用

比较了H_4SiMo_(12)O_(40)、H_3PW_(12)O_(40)、H_4SiW_(12)O_(40)、H_3PMo_(12)O_(40)及铬酸盐对镀锌层钝化效果。H_3PMo_(12)O_(40)钝化的最佳条件为:H_3PMo_(12)O_(40)5g/L,pH 1.1,钝化时间35秒,温度15℃,空留时间10秒,封闭温度100℃(水)。经扫描电镜、XPS、AES、IR和Raman光谱等测定,表明在锌表面形成了一种含有P、Mo、O及Zn的耐蚀性膜。其中钼以Mo(Ⅵ)、Mo(Ⅴ)和Mo(Ⅳ)存在,P/Mo比为1:3.0。推测锌表面形成了一种形如Zn_x(PMo_3)_rO_z/ZnO/Zn的复杂钝化膜。     

氧化铁电极的半导体性能和光电化学——Ⅳ、阳极形成及热形成氧化铁电极的光电化学实验研究

本文指出, 由于热形成氧化铁电极光电流响应的瞬态性质, 所以正用锁定放大器测量出的数值大大超过其代数平均值。阳极形成铁钝化膜的光电响应与热形成氧化铁的相类似, 但有一定差别。目前的实验水平尚不足以监测钝化膜形成过程中的结构性质。但实验证明膜基本形成后, 在理想情况下, 光电流与膜厚在一定范围内成正比。在膜基本形成前, 则光电流之值较大, 偏离正比关系。     

浸没凝胶相转化制备聚合物膜的孔结构及其形成机理

全面地综述了浸没凝胶相转化法制备的聚合物微孔膜的表面和膜中存在的各种孔的结构和形态,从制膜体系的热力学性质和成膜动力学角度解释了各种孔结构形态的形成和生长机理,即膜表面与膜中孔的结构形态由此时制膜体系发生的相分离类型决定,由此可推断出不同的膜层可能有不同的成膜机理。因此,只要掌握了各种膜孔结构形成的机理,通过改变膜的制备条件,控制体系的热力学性质与成膜时动力学扩散是可以实现相转化膜结构的控制。     

添加钇提高不锈钢耐蚀性能的AES研究

用俄歇能谱仪对比研究了添加０．２％Ｙ对高硅不锈钢在９３％Ｈ２ＳＯ４介质中所形成的钝化膜中各元素浓度分布的影响，添加０．２％Ｙ增大了ＳｉＯ２在不锈钢钝化膜中的比例，从而使合金中Ｓｉ可充分形成富ＳｉＯ２的钝化膜。     

The passivity of nickel in phosphate solutions: Part II. Effect of solufion pH

The passivity of nickel has been studied over a wide range of pH (1.5–12.6) in phosphate solutions. The results show that solution pH has a strong effect on the formation and the growth of the passive films. In basic solutions (pH 9.1 and 12.6) and in moderately acidic solution (pH 4.5), the passive film possess the came optical constants but exhibit different growth behaviors. The film formed in the basic solutions does not grow, but the film formed in the pH 4.5 solution increases in thickness with time. In an acidic solution of 1.5 pH, the passive film is composed of two layers: a base layer of partially dehydrated Ni(OH)₂, and an upper, potential-dependent film. The two-layer film evolves with time.     

Passivity of titanium,part 1: film growth model diagnostics

Diagnostic criteria for the growth of the anodic oxide film on titanium in H₂SO₄ are reported. The criteria apply to the generalized high field model, which postulates that the electric field within the film is dependent upon the film thickness, and the point defect model, which describes the electric field as being constant during film growth. The diagnostic criteria show that the PDM more realistically models film growth than does the HFM, and we conclude that in this system the electric field strength is invariant with applied voltage and film thickness. The constancy of the electric field in the passive film on titanium, as demonstrated in this work, is attributed to band-to-band Esaki tunneling, which buffers the electric field against changes in the applied voltage and film thickness.     

气体水合物膜生长动力学研究进展

由于大多数水合物客体不溶于水,水相与客体相界面首先形成一层气体水合物膜,气体水合物膜生长是水合物生长的主要形式,研究水合物膜生长规律对于理解水合物生长动力学及进一步开发促进和抑制水合物生长的应用技术具有重要意义.本文综述了近年来气体水合物膜生长形态、横向生长和增厚生长的理论和实验研究进展.首先介绍了不同客体-水体系(包括气/液界面、液/液界面和气-液-液体系)形成的水合物膜生长形态随实验条件的变化规律,然后分别从横向生长和增厚生长两方面总结了水合物膜生长的实验和模型方面的研究工作,阐述了常见的膜生长速率和膜厚度的测量方法,分析了水合物膜生长的传热和传质机理.同时展望了未来水合物膜生长研究的发展方向.     

Effect of oxygen vacancies in anodic titanium oxide films on the kinetics of the oxygen electrode reaction

The effect of oxygen vacancies in the anodic oxide film on passive titanium on the kinetics of the oxygen electrode reaction has been studied by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Oxide films of different donor density were prepared galvanostatically at various current densities until a potential of 20.0 V_SHE was achieved. The semiconductive properties of the oxide films were characterized using EIS and Mott-Schottky analysis, and the thickness was measured using ellipsometry. The film thickness was found to be almost constant at ∼44.7 ± 2.0 nm, but Mott-Schottky analysis of the measured high frequency interracial capacitance showed that the donor (oxygen vacancy) density in the n-type passive film decreased sharply with increasing oxide film formation rate (current density). Passive titanium surfaces covering a wide range of donor density were used as substrates for ascertaining relationships between the rates of oxygen reduction/evolution and the donor density. These studies show that the rates of both reactions are higher for passive films having higher donor densities. Possible explanations include enhancement of the conductivity of the film due to the vacancies facilitating charge transfer and the surface oxygen vacancies acting as catalytic sites for the reactions. The possible involvement of surface oxygen vacancies in the oxygen electrode reaction was explored by determining the kinetic order of the OER with respect to the donor concentration. The kinetic orders were found to be greater than zero, indicating that oxygen vacancies are involved as electrocatalytic reaction centers in both the oxygen evolution and reduction reactions. This paper was submitted in honor of the many contributions to electrochemistry that have been made by Professor Boris Grafov. The article is published in the original.     

Kinetics of film formation by interfacial polycondensation

An approximate analytical model of film formation by interfacial polycondensation is presented. The analysis requires knowledge of a minimal set of certain kinetic parameters (monomer diffusivities and reaction rate constants) and reaction conditions (monomer concentrations and thickness of the unstirred layer). The process proceeds as a succession of two or three markedly different kinetic regimes. Each regime (insipient film formation, slowdown, and diffusion-limited growth) sets a different pattern of local polymer accumulation, with important implications for the structure of the emerging film. At the incipient stage, a loose polymer film begins to emerge in a fixed narrow region inside the boundary layer, followed by gradual densification of the middle part of the film. A condition for film formation is thus formulated on the basis of our analysis. The model predicts that two different scenarios are possible, which depend on the permeability of the polymer: films with a low permeability to both monomers pass through an abrupt slowdown of film growth, whereas permeable films undergo a smooth transition between the incipient film formation and diffusion-limited regimes. The model incorporates the highly important effects of the accumulation of reactive end groups and the decrease of monomer diffusion with the polymer concentration on the kinetics of the process and film characteristics. In addition, the validity of the utilized mean-field approach is analyzed, and the analysis suggests a direct correlation between the roughness and the thickness of the film. The results are in good agreement with an earlier numerical study and the direct structural studies of polyamide membrane films.     

The passivity of nickel in phosphate solutions: Part I. Effect of temperature

The effect of temperature on the passivity of nickel in 0.1 M Na₂HPO₄ solution was studied by combined electrochemical-ellipsometric techniques. The optical constants for the passive films were found to be slightly dependent on temperature over the range 25–90°C. At all temperatures, the passive film forms instantaneously and does not grow during the 1 h experimental period. However, the thickness of the film is potential and temperature-dependent. The principal effect of temperature is to modify the thickness of the passive film formed on nickel in phosphate solution.     

Re-defining the kinetics of redox reactions on passive metal surfaces

It is known that the kinetics of redox reactions occurring on the surfaces of passive metals depend upon the properties of the passive film, ostensibly due to quantum mechanical tunnelling (QMT) of electrons and holes between the metal and the redox couple at the barrier layer/solution (bl/s) interface. In this paper, the tunnelling probability is used to inter-convert the exchange current densities for the redox reactions occurring at the bl/s interface and on the hypothetical bare metal surface. We review our previous work on combining QMT theory with the point defect model (PDM), which provides an analytical expression for the bl thickness as a function of voltage. By combining QMT theory and the PDM, we derive a modified form of the generalized Butler-Volmer equation that requires as input only the kinetic parameters for the redox reaction on the hypothetical bare surface and parameters contained in the PDM. The application of the theory is illustrated with reference to the corrosion of carbon steel in concrete pore solution, to calculating the corrosion potential of, and crack growth rate in, sensitized type 304 SS in boiling water reactor (BWR) coolant circuits, and the use of hydrogen oxidation on platinum to determine the thickness of the bl as a function of voltage and temperature. This illustrates a new, powerful technique for probing the formation of passive films on metal surfaces.

     

Fe基合金钝化膜点蚀敏感性的电化学研究

应用电位扫描、交流阻抗、电化学噪声等方法研究Fe及其合金在中性水溶液中钝化膜的形成过程、电子性质和点蚀敏感性以及不同微组织结构间的相互作用.结果表明:由Mott-Schot tky关系式确定钝化膜的电子性质仅限于较窄的低电位范围;在较高电位下,电容倒数与电位的线性关系当归因于钝化膜厚度的变化;反映钝化膜缺陷的电子性质与合金的点蚀敏感性有关,钝化膜电子供给体浓度越高,点蚀倾向越强。钝化膜的电子性质受钝化膜形成电位、钝化剂种类以及合金的微组织结构影响;不同微组织结构之间存在相互作用,这种相互作用能够诱导缺陷较大的一方发生点蚀。铁素体与珠光体和/或马素体相互作用时,点蚀在铁素体形成和发展.     

铜在甲胺介质铁氰化钾化学-机械抛光液中的电化学行为

二甲氧基苯胺;铜在甲胺介质铁氰化钾化学-机械抛光液中的电化学行为     

Real-Time Measurement of Thin Film Thickness During Plasma Processing

An in situ single point two-color laser interferometer is used to monitor in real-time the thickness of thin transparent films during processing. The instantaneous change of film thickness is determined by comparing the measured laser reflection interference to that calculated by a model. The etch or deposition rates of the film are determined within 1–2 seconds. The film thickness is also determined in real-time from the phase difference of the reflected laser intensity between the two laser colors. Use of two-color laser interferometry improves the accuracy of the calculated etch or growth rates of the film considerably. Moreover, the two colors provide a clear distinction between film etching and deposition, which may often occur during the same process, and can not be determined by a single color interferometer. The uniformity of the film's etch or deposition rates across the substrate is monitored by an in situ full-wafer image interferometer. The combined use of these two sensors provide instantaneous information of the film thickness, etch or growth rates, as well as time averaged uniformity of the process rates. This diagnostic setup is very useful for process development and monitoring, which is also suitable for manufacturing environment, and can be used for real-time process control.