Metal ion release and surface composition of the Cu-18Ni-20Zn nickel-silver during 30 days immersion in artificial sweat

In order to study nickel ion release associated with nickel allergy, Cu-18Ni-20Zn nickel-silver alloy was immersed in artificial sweat and Ringer physiological solution for 30 days. Dissolution of metal ions was measured as a function of time, and the characteristics of the solid surface layer formed after 30 days were studied by SEM/EDS and XPS. The dissolution of nickel prevails over dissolution of copper and zinc. Nickel release in artificial sweat is approximately 10 times higher than in Ringer physiological solution and in both solutions the nickel release exceeds 0.5 μg cm⁻² week⁻¹, the threshold above which the allergy is triggered. Evidence of selective nickel dissolution is reported. The composition of the surface layer formed in artificial sweat and in Ringer physiological solution differs in the content of nickel and chlorine. In artificial sweat, the major constituents of the surface layer are dominantly oxides, Cu₂O and ZnO, with traces of chlorine. In Ringer physiological solution, the composition of the surface layer changes to a mixture of oxides, chlorides and/or oxychlorides. Two components peaks were detected in the Cl 2p_3/2 peak; however, it was not possible to distinguish the exact nature of the chloride compound formed. The mechanism of nickel release is discussed as a function of the composition of the solution.     

Characterization of Schottky barrier diodes fabricated from electrochemical oxidation of α phase brass

By careful selection of chloride ion concentration in aqueous sodium chloride, electrochemical oxidation of α phase brass is shown to permit fabrication of either p-type copper (I) oxide/metal or n-type zinc oxide/metal Schottky barrier diodes. X-ray photoelectron and Auger electron spectroscopies provide evidence that barrier formation and rectifying qualities depend on the relative surface abundance of copper (I) oxide and zinc oxide. X-ray diffraction of the resulting diodes shows polycrystalline oxides embedded in amorphous oxidation products that have a lower relative abundance than the diode forming oxide. Conventional I/V characteristics of these diodes show good rectifying qualities. When neither of the oxides dominate, the semiconductor/metal junction displays an absence of rectification.     

苯并三氮唑对铜和铁缓蚀作用的拉曼光谱研究

本文利用现场拉曼光谱研究了中性含氯离子溶液中苯并三氮唑在铜和铁电极表面的吸附以及成膜行为,结果表明苯并三氮唑能强烈地化学吸附于铜电极和铁电极表面,形成类似［Ｍｎ（ＢＴＡ）ｐ］的配合物膜,一定程度上阻止了膜内外物质的交换,对金属起缓蚀作用。另一方面两种金属表面配合物膜均具有电位依赖性：在铜电极表面,当外加电位由－０．５Ｖ负移至－０．９Ｖ时,发生了由［Ｃｕ（Ⅰ）（ＢＴＡ）］ｎ向［Ｃｕ（Ⅰ）Ｃｌ（ＢＴＡＨ）］４的转变;而在铁电极表面当外加电位由－０．６Ｖ负移至－１．２Ｖ时,最初形成的表面配合物［Ｆｅｎ（ＢＴＡ）ｐ］则很可能转变成类似于［Ｆｅｎ（Ｃｌ）ｐ（ＢＴＡＨ）ｍ］的配合物,从而使得ＢＴＡＨ对铜、铁的缓蚀能力均有所下降。     

An electroactive co-polymer as corrosion inhibitor for steel in sulphuric acid medium

The corrosion behavior of mild steel in sulphuric acid solution containing various concentrations of a co-polymer formed between maleic anhydride and N-vinyl-2-pyrrolidone (VPMA) was investigated using weight-loss, polarization and electrochemical impedance techniques. The polymer acts as an effective corrosion inhibitor for steel in sulphuric acid medium. The inhibition process is attributed to the formation of an adsorbed film of co-polymer on the metal surface which protects the metal against corrosion. Scanning electron microscopy (SEM) studies of the metal surfaces confirmed the existence of an adsorbed film. The adsorption followed the Langmuir isotherm. The protection efficiency increased with increase in inhibitor concentration and decreased with increase in temperature and acid concentration. The thermodynamic functions of the adsorption and dissolution processes were evaluated.     

Study on electrical behaviour of copper and its alloys containing dispersed nanoparticles

Nanoparticles can be added to metals to tune their properties for numerous applications. Recently extensive research has been conducted to measure the mechanical properties of nanoparticle reinforced metals. However, few theories exist to understand how nanoparticles interact with metals to affect their electrical performance, partly due to the difficulty in producing bulk metal samples, containing dispersed nanoparticles. In this work, copper and copper alloys (Cu, Cu-40 wt% Zn, and Cu-60 wt% Ag) containing dispersed tungsten carbide (WC) nanoparticles of more than 20 vol% were successfully fabricated via solidification processing. The experimental results show that copper and its alloys with an increasing volume fraction of nanoparticles, the electrical conductivity of the samples decays exponentially. Therefore, a theoretical model, compatible with the Nordheim's rule was established to predict the electrical behaviour of metals containing dispersed nanoparticles. This new model on the electrical behaviour of copper nanocomposites is experimentally validated by low-temperature resistivity measurements and electronic heat capacity measurements above Debye temperature.     

苯并三氮唑缓蚀铜粉中含氧量的测定

研究了不同条件下苯并三氮唑的紫外吸收光谱,最大吸收峰为273 nm,常温下吸收强度不受温度影响,浓度线性范围为0～2.2 μg ·mL-1,检出限为0.02 μg ·mL-1,摩尔吸光系数为5.41×104 L·mol-1·cm-1;建立了苯并三氮唑缓蚀铜粉中含氧量的测定方法。鉴于缓蚀铜粉由金属铜、铜氧化物和苯并三氮唑保护膜组成,用盐酸-H₂O₂分解样品后,分别以EDTA配位滴定和紫外光谱法测定化学缓蚀铜粉中铜和苯并三氮唑含量,差减求出该铜粉含氧量。方法经济,仪器简单,操作方便,标准偏差=1.7%,变异系数为7.6%。结合国家标准方法,通过电解铜粉在成膜前后含氧量分析比较,提出的方法测定结果令人满意。     

Effect of sulfide pollution on the stability of the protective film of benzotriazole on copper

Benzotriazole (BTAH) is an excellent inhibitor for the corrosion of copper and many of its alloys in unpolluted media. Protection is attributed to the formation of a film of Cu(I)BTA. Injection of sulfide ions into a benzotriazole inhibited salt water damages the protective Cu(I)BTA film very rapidly, increases the corrosion rate and leads to the formation of copper sulfide. This effect is quite marked at a sulfide concentration as low as 10⁻⁵ M (about 0.3 ppm sulfur) in the presence of 10⁻² M BTAH, which is 1000-fold greater than that of the sulfide ion. The intensity of sulfide attack increases with its concentration.Prolonged pre-passivation of copper in the BTAH protected medium even at high concentration does not markedly improve the resistance of the protective film to sulfide attack. This finding is contrary to a well-documented phenomenon in unpolluted media where the inhibiting efficiency of BTAH increases with the time of immersion and the concentration of the inhibitor. X-ray photoelectron spectroscopy (XPS) reveals the presence of both sulfide and BTAH on the corroded surface indicating that sulfide attack is localized.     

可见吸收光谱法研究铜锌超氧化歧化酶活性中心金属离子与氯…

应用可见吸收光谱首次研究了铜锌超氧化酶（Ｃｕ２Ｚｎ２ＳＯＤ）活性中心金属离子在一定缓冲溶液中与无机氯化钴的直接相互作用，讨论了加入不同比例量的氯化钴，不同的ｐＨ值，不同酸盐及作用的平衡时间对这种相互作用的影响，结果发现，ＣｏＣｌ２中的Ｃｏ（Ⅱ）与Ｃｕ２Ｚｎ２ＳＯＤ中的Ｚｎ（Ⅱ）有交换作用，形成部分的Ｃｕ２中的Ｃｏ２ＳＯＤ，且上述四种因素对此均有不同程度的影响，本研究开创了金属酶活性中心金属离子与外     

Initial oxidation of brass induced by humidified air

Complementary surface and near-surface analytical techniques have been used to explore a brass (Cu-20Zn) surface before, during, and after exposure in air at 90% relative humidity. Volta potential variations along the unexposed surface are attributed to variations in surface composition and resulted in an accelerated localized growth of ZnO and a retarded more uniform growth of an amorphous Cu₂O-like oxide. After 3 days the duplex oxide has a total mass of 1.3 μg/cm², with improved corrosion protective properties compared to the oxides grown on pure Cu or Zn. A schematic model for the duplex oxide growth on brass is presented.     

X-ray photoelectron spectroscopy for surface film analysis in corrosion research

Surface films on metals and alloys often protect them from reaction with the environment, and hence a knowledge of their protective properties and composition could be invaluable for predicting their corrosion behaviour. XPS (x-ray photoelectron spectroscopy) could provide a quantitative analysis of the chemical composition, the nature of valence states and elemental distribution within the surface films. The present paper reviews the potential of this technique in corrosion studies. A brief review of the work done on the passivation of iron and iron-chromium alloys and on the inhibition studies on copper base alloys has been given. A few examples of investigations carried out at authors’ laboratory are also included. An attempt has been made to establish a correlation between the compositions of the films formed and corrosion behaviour of carbon steel in 10.5 pH lithium hydroxide solution and of Cu-Ni alloys and sacrificial Al-Zn-Sn alloys in synthetic sea-water.     

Structures of nanowires with Zn-ZnO:CuO junctions for detecting ethanol vapors

The synthesis of ZnO-ZnO:CuO structures in the form of overlapping layers of nanowires of pure and copper oxide-doped zinc oxide is described. These structures are tested as ethanol vapor sensors. The following two-stage method is used to form ZnO:CuO nanowires. At the first stage, ZnO nanowires are formed by chemical deposition from a solution. At the second stage, arrays of ZnO nanowires are coated with a copper-containing layer. The CuO content on the surface of ZnO nanowires is changed by varying the number of immersions in a Cu(NO₃)₂ solution. The formed structures are studied by scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis. The interaction of the grown sensor structures with ethanol vapors is analyzed by measuring the potential difference between the layers of pure zinc oxide and copper oxide-modified zinc oxide in the temperature range 190–300°C. The response of the sensor is investigated at various ethanol vapor concentrations and detection temperatures.     

X-ray absorption study of Cu,Zn SOD under high pressure

Abstract

We have investigated Cu, Zn Superoxide Dismutase (Cu, Zn SOD) metal sites at high pressure using X-ray absorption. XAS (X-ray Absorption Spectroscopy) gives information on local structure and it is particularly suited to metal site investigation. To the best of our knowledge, this is the first time that protein conformational states have been investigated using the high pressure XAS technique. Cu, Zn SOD catalyses the dismutation of toxic oxygen radicals produced in cells; this reaction occurs at the copper metal site. Structural changes around the copper, induced by pressure, can be directly related to protein substates. Their characterisation is thus important in the understanding of protein activity.

The high-pressure device was a Paris-Edinburgh large volume cell.

Experiments were performed on lyophilised Cu, Zn SOD between 0 and 48 kbar at the copper and zinc K-edges. The two metal local atomic environments have a different behaviour as pressure increases: copper exhibits a more flexible environment; on the contrary, zinc shows small structural modifications. We have identified a state, formed between 3 and 8 kbar, which is stable up to 48 kbar.     

Promoting effect of low concentration of benzotriazole on the corrosion of Cu10Ni alloy in sulfide polluted salt water

The interaction of benzotriazole (BTAH) with the surface of a corroding copper–nickel alloy in a sulfide polluted salt solution reveals a change in its role from an inhibitor to a promoter of localized corrosion as its concentration changes. A concentration of BTAH ≥5 × 10⁻⁴ M inhibits the corrosion reaction in both the polluted and the unpolluted media. On the other hand, a concentration of 10⁻⁴ M BTAH promotes the localized corrosion of the alloy in the polluted medium while it acts as an inhibitor in the unpolluted salt solution. This finding is substantiated by measurements of mass loss and current transients and examination of the surface by SEM microscopy.     

ZnO thin films deposition by spray pyrolysis: Influence of precursor solution properties

Zinc oxide (ZnO) thin films were deposited by spray pyrolysis technique using different precursors. Three starting solutions salts namely: zinc acetate, zinc chloride and zinc nitrate were used. The properties of these solutions and their influence upon ZnO films growth rate are investigated. The obtained results indicate that the dissociation energy of the starting solution plays an important role on films growth rate. A linear relationship between the solution dissociation energy and the growth rate activation energy was found. However, the surface tension of the used solution controls the droplet shape impact. Both solution surface tension and dissociation enthalpy alter the microstructure of the formed film. Films deposited with zinc acetate are characterized by a smooth surface, dense network and high transparency, while films deposited with zinc chloride have a better crystallinity and low optical transmittance.     

Surface characteristics of Zinc–TiO2 coatings prepared via micro-arc oxidation

Titanium (Ti) and its alloys are widely used as metallic biomaterials for fabrication of dental and orthopedic implants due to their favorable biocompatibility and corrosion resistance in a body environment. However, the thin oxide layer (TiO₂) on Ti substrate formed naturally in air or in many aqueous environments is bioinert and surrounded by fibrous tissues without producing any chemical or biological bond to bone when implanted. In the present work, Zinc-incorporated porous TiO₂ coatings (Zn–TiO₂) were prepared on Ti substrate by micro-arc oxidation (MAO) technique in the zinc gluconate-containing electrolyte. The surface morphology, cross-sectional morphology, composition, and phase of the coatings were analyzed using scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffractometry, respectively. Surface topography and roughness of the coatings were investigated by atomic force microscopy operated in tapping mode. The results showed that Zn was successfully incorporated into the porous TiO₂ coatings, which did not alter apparently its surface topography and phase composition. In conclusion, the formation of porous Zn–TiO₂ coatings endow Ti with potential bioactivity and antibacterial activity, and we believe that the porous Zn–TiO₂ coatings on Ti by MAO technique might be promising candidates for orthopedic and dental implants     

Piezoelectric film electro-deposition for optical fiber sensor with ZnO coating

The piezoelectric film electro-deposition for optical fiber sensor with ZnO coating is studied. The zinc oxide plating film is made on the copper surface directly by cathodic electro-deposition in the Zn(NO3)2 single salt aqueous solution systems. The influences of main experimental conditions on the properties of ZnO thin film in the electro-deposition processes are analyzed and a stable, practical and economic technique is obtained.     

Influence of zinc ion implantation on surface nanomechanical performance and corrosion resistance of biomedical magnesium-calcium alloys

It is believed that magnesium and its alloys may find applications in biomedical fields as implants, bone fixation devices, and tissue engineering scaffolds. However, their corrosion rate must be controlled. In this study, biomedical magnesium-calcium (Mg-Ca) alloys were ion-implanted with zinc. The surface nanomechanical performance and corrosion behavior of the ion-implanted Mg-Ca alloys are determined. The results show that zinc ion implantation at a dose of 0.9 × 10¹⁷ ions/cm² significantly improves the surface hardness and modulus. However, the results on corrosion resistance reveal that zinc ion implantation degrades the corrosion behavior of Mg-Ca alloys. Thus, zinc is not a favorable element for the ion implantation treatment of biomedical Mg-Ca alloys.     

Effect of the chemistry and structure of the native oxide surface film on the corrosion properties of commercial AZ31 and AZ61 alloys

The purpose of this study has been to advance in knowledge of the chemical composition, structure and thickness of the thin native oxide film formed spontaneously in contact with the laboratory atmosphere on the surface of freshly polished commercial AZ31 and AZ61 alloys with a view to furthering the understanding of protection mechanisms. For comparative purposes, and to more fully describe the behaviour of the native oxide film, the external oxide films formed as a result of the manufacturing process (as-received condition) have been characterised. The technique applied in this research to study the thin oxide films (thickness of just a few nanometres) present on the surface of the alloys has basically been XPS (X-ray photoelectron spectroscopy) in combination with ion sputtering. Corrosion properties of the alloys were studied in 0.6 M NaCl by measuring charge transfer resistance values, which are deduced from EIS (electrochemical impedance spectroscopy) measurements after 1 h of exposure. Alloy AZ61 generally showed better corrosion resistance than AZ31, and the freshly polished alloys showed better corrosion resistance than the alloys in as-received condition. This is attributed to a combination of (1) higher thickness of the native oxide film on the AZ61 alloy and (2) greater uniformity of the oxide film in the polished condition. The formation of an additional oxide layer composed by a mixture of spinel (MgAl₂O₄) and MgO seems to diminish the protective properties of the passive layer on the surface of the alloys in as-received condition.     

Effect of copper addition on some properties of rapidly solidified lead-free Sn–-10 wt% Zn alloys

This study aimed at investigating the effect of adding copper (Cu) on some properties of the lead-free alloys which rapidly solidified from melt. X-ray analysis, hardness, elastic modulus, electrical conductivity and resistivity were studied. The results indicated that the alloy hardness and elastic modulus improved by increasing the copper (Cu) content and decreasing the zinc (Zn) content. The electrical conductivity ranged from 0.250 to 0.847?×?10⁷ ohm^?1 m^?1 for the alloy under study. The electrical resistivity increases linearly with temperature until the melting point is reached. The residual resistivity results from disturbances in the lattice rather than caused by thermal vibration and the most drastic increases in the residual resistivity are caused by foreign atoms in solid solution with matrix metal. The electrical resistivity values ranged from 11.8 to 40?×?10^?8 ohm m, when the copper content changed from 0.0 to 2.0 wt% and zinc changed from 8.0 to 10.0 wt%.     

Highly adhesive metal plating on Zylon fiber via iodine pretreatment

Highly adhesive metal plating was performed on poly(p-phenylene-2,6-benzobisoxazole) fiber named Zylon^® via iodine pretreatment followed by electroless plating. First, iodine components were selectively doped into the inner part of the fiber near the surface through iodine vapor exposure. The doped iodine was converted to palladium iodide particles by treating with palladium chloride solution. After the reduction of the iodide to metal palladium particles, electroless copper plating was conducted on the fiber. A uniform copper layer was deposited on the fiber surface and exhibited high durability in durability tests such as ultrasonic exposure, tape peeling-off, and corrosion in NaCl solution. This durability was attributed to the palladium particles formed at the fiber surface that served as an anchor for the plated layer as well as an electroless plating catalyst. The plated fibers also possessed electrical conductivity. Although the tensile strength of the Zylon^® fiber decreased from 5.8 to 4.9 GPa after undergoing the pretreatment and plating processes, the light shielding effect improved the light resistance of the plated fibers in terms of tensile properties. After 18 days of xenon lamp exposure, the plated fibers retained 74% of its initial strength, whereas that of untreated fibers decreased to 43%.