Cu/Ni/Au multilayers by electrochemistry: A crucial system in electronics - A critical review

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Single-step electrodeposition of superhydrophobic black NiO thin films

International audienceBlack finished surfaces have extensive applications in many domains, such as optics, solar cells, and aerospace. The single step electrodeposition of superhydrophobic black NiO films from a dimethyl sulfoxide based electrolyte is described in this paper. The physicochemical properties of the obtained film were characterized using Scanning Electron Microscopy, X-ray Diffraction, and electrochemical tests (Electrochemical Impedance Spectroscopy and potentiodynamic polarization). A rough surface with a low reflection of light was formed after the deposition process that increased the contact angle of water from about 87º (for bare Cu) to 163º (in presence of the black coating), which improved the corrosion resistance of the Cu substrate by about 30%. The formed black NiO film revealed a notably high stability and kept its appearance even after corrosion tests

Sorption Properties of Chitosan in the Refining of Rough Indium

The degree of purity of cathode deposits during the electrochemical refining of rough indium depends on the content of impurity metals in the electrolyte. In this work, an additional sorption purification of the refining electrolyte was carried out in order to reduce the content of such impurity metals as cadmium, lead, copper. Chitosan was used as a sorbent due to high sorption properties with respect to heavy metal ions. The determination of the concentration of the studied metals before and after the sorption was carried out by the method of differential pulse anodic stripping voltammetry (DPASV). The experimental results allowed to calculate the amount of metal sorbed by chitosan and the efficiency of its removal. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and isotherm constants were determined. The Langmuir model agrees very well with experimental data. An inductively coupled plasma optical emission spectroscopy (ICP-OES) method was used to determine the presence of impurity metals and the degree of purity of electrorefined indium. The use of chitosan as a sorbent in the purification of rough indium allows to reduce the concentration of impurity metals in cathode deposits and to increase the content of the base metal to 99.9994%

Influence of composition, bonding characteristics and microstructure on the electrochemical and optical stability of AlOxNy thin films

Thin films of AlOxNy were deposited by magnetron sputtering in a wide composition range. Different structures and morphologies were observed, depending on the composition and bonding states, which opened the possibility to tailor the properties of this oxynitride system between those of pure Al and those of nitride and oxide films. In a wide range of stoichiometries, one can report the formation of nanocomposite porous films, where Al nanoparticles are dispersed in an amorphous matrix of AlOxNy. The electrochemical behaviour of the films was studied in isotonic NaCl solution. It was observed that the pitting 2 potential characteristic of aluminium disappears with the incorporation of oxygen and nitrogen in the films, being replaced by a smooth current increase. Electrochemical impedance spectroscopy performed during 35 days showed that the corrosion resistance of the films steadily increases. The unusual optical reflectance profile of some films is maintained after immersion for several months.Fundação para a Ciência e a TecnologiaPrograma Pessoa 2010/2011, Cooperação Portugal/França, Proc.º 441.00, Project“COLOURCLUSTER”

Amélioration des propriétés de corrosion de film minces de NiP par utilisation de différents additifs

International audienceNiP amorphous coatings are considered as important engineering alloys. In this paper, the effects of various additives on the properties of NiP thin films were investigated, including saccharine, glycine, pyridinium propyl sulfonate, coumarin, sodium citrate, and cerium sulfate. Potentiodynamic polarization and electrochemical impedance spectroscopy tests, scanning electron microscopy, X-ray fluorescence and diffraction, and atomic force microscopy were employed to study the properties of the samples. It was found that a proper concentration of these additives, except saccharine, noticeably improved the corrosion resistance, especially at high potentials (about 25% increase in instantaneous corrosion efficiency and about 300% in corrosion efficiency at high potentials) and decreased the surface roughness (by about 10 to 55 %) of NiP thin films. Thinner, more uniform, and less porous coatings were formed in the presence of additives. Except saccharine, all the additives enhanced the P content of NiP films, which thus kept their amorphous structure; saccharine highly suppressed the incorporation of P inside the Ni lattice and a mixed amorphous-crystalline structure was stabilized

Corrosion Performance of Lamellae nanostructured fluorinated organic coatings applied on steel.

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Sulfonated polyphenyl ether by electropolymerization

Electropolymerization of sulfonated phenol was for the first time achieved and studied by cyclic voltammetry (CV) and chronoamperometry on stainless steel substrates. The obtained sulfonated polyphenyl ether was characterized in terms of impedance spectroscopy, nuclear magnetic resonance (NMR), energy dispersive X-ray analysis (EDX). X-ray diffraction (XRD) and Fourier-Transform Infrared (FTIR) spectroscopy. Dense films of micrometer thickness can be obtained: the proton conductivity is about 3 mS/cm at room temperature

Tracking the fate of γ-aminopropyltriethoxysilane from the sol state to the dried film state

International audienceIn this work, 29Si nuclear magnetic resonance and Fourier-transformed infrared spectroscopy were combined to study the hydrolysis and polycondensation of γ-aminopropyltriethoxysilane (γ-APS), both in the liquid sol state and in the film state. γ-APS sols were prepared in methanol or ethanol solvent in the pH range from 5.7 to 11 and deposited. The aim of the present study was to get the most complete picture in regard to the chemical events and time scale of these events. Transesterification reactions between γ-APS and methanol result in faster kinetics in methanol compared to ethanol. γ-APS films were deposited on aluminium and dried at ambient conditions (23 °C, 55% relative humidity). The silane films reached a chemical equilibrium in a couple of minutes (natural pH of 11) to 1 h (pH 7) depending on the pH of the silane solution. From a practical perspective, the results obtained here might give some clues to define an optimized schedule for the application of γ-APS coupling agent to metals