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copper (Cu) and stainless steel 316 L are widely used for biomedical applications, such as intrauterine devices and orthopedic/dental implants. Amino acids are abundantly present in biological environments. We investigated the influence of select amino acids on the corrosion of Cu under naturally aerated and deaerated conditions using a phosphate-free buffer. Amino acids increased the corrosion of Cu under both aeration conditions at pH 7.4. Cu release was also significantly (up to 18-fold) increased in the presence of amino acids, investigated at pH 7.4 and 37 °C for 24 h under naturally aerated conditions. Speciation modelling predicted a generally increased solubility of Cu in the presence of amino acids at pH 7.4. 316 L, investigated for metal release under similar conditions for comparison, released about 1,000-fold lower amounts of metals than did Cu and remained passive with no change in surface oxide composition or thickness. However, amino acids also increased the chromium release (up to 52-fold), significantly for lysine, and the iron release for cysteine, while nickel and molybdenum release remained unaffected. This was not predicted by solution speciation modelling. The surface analysis confirmed the adsorption of amino acids on 316 L and, to a lower extent, Cu coupons. [ABSTRACT FROM AUTHOR]

The properties of a liquidlike layer (LLL) at the gold/frozen electrolyte interface are studied by using the quartz crystal microbalance (QCM). It was found that at temperatures well below the melting point of the electrolyte, in the range of -2 to -7 degree C, the QCM immersed in a frozen electrolyte shows detectable resonance, the parameters of which depends strongly on temperature.

A study is conducted to examine premelting at the ice/gold and the frozen electrolyte/golf interfaces with the help of quartz-crystal microbalance. The findings indicate that in a certain range of temperature the resonance of the QCM is readily detectable and the parameters of the resonance depend on temperature as well as the shape of the resonance is very different from that observed for the QCM in contact with liquids.

The effect of surface roughness on the response of the QCM has been considered, both theoretically and experimentally. A new theoretical approach to the description of the effect of roughness on the response of the QCM is proposed that accounts for the multiscale nature of roughness. Performing experiments in liquids having a wide range of viscosity and density made it possible to understand, for the first time, what characteristics of roughness influence the QCM experiments. The most important conclusion of the current study is that, to understand the experimental data, one has to take into account at least two types of roughness: slight and strong. We found that measurements of the frequency shift observed are not sufficient for the interpretations of the experimental data observed, and a full analysis of the impedance spectrum is called for.

The strategy for the permanent disposal of high‐level nuclear waste in Canada involves sealing it in a copper‐coated steel container and burying it in a deep geologic repository. During the early emplacement period, the container could be exposed to warm humid air, which could result in the condensation of nitric acid, produced by the radiolysis of the humid air, on the copper surface. Previous studies have suggested that both nitrate and oxygen reduction will drive copper corrosion, with the nitrate reduction kinetics being dependent on the concentration of soluble copper(I) produced by the anodic dissolution of copper in the reaction with oxygen. This study focused on determining the kinetics of nitrate and oxygen reduction and elucidating the synergistic relationship between the two processes. This was investigated using corrosion potential and polarization measurements in conjunction with scanning electron microscopy and X‐ray photoelectron spectroscopy. Oxygen reduction was shown to be the dominant cathodic reaction with the oxidation of copper(I) to copper(II) by nitrate, promoting the catalytic cycle involving the reaction of copper(II) with copper to reproduce copper(I). [ABSTRACT FROM AUTHOR]

A device allowing direct optical measurement of the displacement was used to measure the thickness of the liquid-like layer. The results were correlated with the calculations of the thickness based on admittance data of quartz crystal microbalance, measured at the same time.

The kinetics of oxygen reduction have been studied electrochemically on the Ni-Cr-Mo(W) Alloy C-22 in 5 M NaCl at 70°C using potentiostatic and voltammetric techniques and electrochemical impedance spectroscopy. Oxygen reduction was observed to occur at low potentials on defective oxide films containing a high concentration of anion vacancies and appeared to proceed by a combination of 2-electron and 4-electron transfer processes. At more positive potentials a passive film comprising a CrIII-dominated barrier layer at the alloy/oxide interface and a Mo/W enriched outer layer at the oxide/solution interface was formed, and oxygen reduction was completely suppressed. Oxygen reduction could be revived after transpassive degradation of the oxide film at more positive potentials, and appeared to be catalyzed on the MoVI/WVI surface film. [ABSTRACT FROM AUTHOR]

The composition of anodically grown oxide films on Alloy 22, a Ni-Cr-Mo(W) alloy, has been investigated in 5 mol l−1 NaCl at room temperature using X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. For applied potentials up to 0.2 V (vs Ag/AgCl (saturated KCl solution)), a Cr(III) oxide barrier layer develops at the alloy/oxide interface accounting for the excellent passivity demonstrated to prevail in this potential region by previous electrochemical impedance spectroscopy measurements. At higher potentials, this layer is destroyed by defect injection as Cr(III) is oxidized to the more soluble Cr(VI). The overall oxide/hydroxide film thickness is, however, increased as Mo(VI)/W(VI) species accumulate at the oxide solution interface. The potential of 0.2 V at which the barrier layer switches from growth to destruction coincides with the previously demonstrated threshold potential for the initiation of crevice corrosion. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Four specimens of uranium dioxide doped with rare-earth oxide (Y2O3) and/or metal particles (Pd) i.e., UO2, UO2-Y2O3, UO2-Y2O3-Pd, UO2-Pd were surface and electrochemically characterized using scanning electron microscopy (SEM/EDX), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry. Surface analyses showed that the dopants are present as a separate phase in the UO2 matrix and all oxides are non-stoichiometric and contain a large number of defect clusters. Voltammetry shows anodic oxidation begins at sub-thermodynamic potentials and the presence of multiple cathodic reduction peaks indicates the presence of a number of structural domains with different electrochemical reactivities. Corrosion potential (ECORR) and polarization resistance measurements (Rp) in the presence of H2O2 suggests that the anodic reactivity of all the specimens is comparable and high compared to 1.5 at% SIMFUEL. The lower Rp values obtained on the doped specimens is consistent with the presence of readily oxidizable cuboctahedral clusters in the oxide matrix. [Copyright &y& Elsevier]