A. B. Shein

The effect of anions on the anodic dissolution of nickel silicide in sulfate electrolytes

Anodic dissolution of nickel and nickel silicide in a 0.5 M H2SO4 solution in the presence of halide and thiocyanate ions is studied with the use of cyclic voltammetry. Main regularities of the effect of anions on the mechanism and kinetics of the anodic dissolution of the metal and its silicide are found. The results obtained reveal different nature of the passivation processes and different compositions of the oxide films formed on Ni and NiSi.

Anodic Dissolution of Iron Silicides in Alkaline Electrolyte

Anodic dissolution of iron and its silicides (FeSi, FeSi2, as well as the eutectic alloy FeSi2-Si) and pure Si, in 0.1 to 5.0 N NaOH solutions is studied by cyclic voltammetry and x-ray photoelectron spectroscopy. Principal characteristic features of the silicide anodic dissolution are revealed and the composition of surface films investigated. It is shown that, despite an increase in Si solubility at higher pHs, the iron silicides are highly resistant to anodic dissolution due to especial protective properties of the complex oxide surface film.

Effect of the Metal Component on Anodic Dissolvability of Iron, Cobalt, and Nickel Silicides

The anodic dissolution of Fe, Co, Ni, and FeSi, CoSi, and NiSi monosilicides in 0.5 M H2SO4is studied by the methods of electrochemistry, electron microscopy, and atomic absorption analysis. The anodic behavior of individual metals does not unambuguously determine the anodic resistance of silicides. Silicide NiSi is considerably less resistant than CoSi and FeSi, though, under similar conditions, individual Ni dissolves slower than Fe and Co. Different anodic resistance of FeSi, CoSi, and NiSi is explained by different structures of their crystal lattices.

Effect of anodic surface treatment of cobalt silicides on the hydrogen evolution reaction

Effect of the anodic surfaces treatment of cobalt silicides with different content of the metal and silicon components on the mechanism and kinetics of hydrogen evolution in acid solutions is studied.

Environmental and inherent factors that affect hydrogen cathodic evolution on silicides of the iron family metals

Scientifically proven search for new electrode materials with different functions is an actual problem of applied electrochemistry. Promising are intermetallic and metal-like compounds of various composition, a lot of which exhibits extremely high corrosion resistance and low hydrogen overpotential.

Choice of effective corrosion inhibitors for acid treatment of wells

Protective effects of some commercial corrosion inhibitors (VNPP-2V, KI-1, and IKU) in fluids used for acid treatments of oil wells were studied by gravimetric and electrochemical measurements. The inhibitors were tested in the presence of Fe3+ ions and in “aged” inhibited fluids.

Peculiarities of the Anodic Dissolution of a Powder NiSi Electrode

The dissolution of solid and powder NiSi electrodes in a 0.5 M H2SO4containing 0–50 mM sodium fluoride is studied by methods of quasi-steady-state and cyclic voltammetry. The powder electrodes are inferior to solid ones in corrosion resistance and are less readily passivated compared to smooth NiSi and even Ni electrodes. The anodic dissolution rate of NiSi considerably increases in the presence of fluoride; the effect being more pronounced in the case of smooth electrode.

Electrochemical behavior of Co2Si in acids

The dissolution of Co2Si in 0.5 M H2SO4 containing 0–100 mM fluoride was studied electrochemically, by electron microscopy, and X-ray microanalysis. In the base solution, the anodic corrosion resistance of Co2Si silicide was two to four exponents higher than that of cobalt. During the anodic polarization of Co2Si, the selective dissolution of cobalt takes place concurrently with the oxidation of silicon to SiO2. The process is controlled by the diffusion of Co in the intermetallic compound and the diffusion of oxidized Co in the superficial layer of hydrated SiO2.

Effects of arylthio-and arylseleno(methoxy)methanes on acid corrosion of CT3 steel

The effects of various arylthio-and arylseleno(methoxy)methanes on corrosion of CT3 steel in sulfuric and hydrochloric acid solutions were studied by gravimetric and voltammetric methods. Some compounds of theses classes were found to be effective inhibitors of the acid corrosion of CT3 steel. The presence of the-X-CH2-O-CH3 groups (X = S or Se) in aromatic amines and their derivatives enhanced their inhibitive properties. However, because these groups are highly hydrophobic, the molecules of inhibitors should contain other fragments that ensure sufficient solubility.

Examination of trialkyl-substituted sulfonium, selenonium, and telluronium salts as inhibitors of acid corrosion of iron and steel

The effect of a number of trialkyl-substituted sulfonates, selenates, and tellurates on free corrosion and its partial processes on iron and steels in sulfuric and hydrochloric acid solutions was examined with the use of gravimetric, voltammetric, and capacitance methods. The considered onium compounds of the elements of 6A group, especially with aromatic substituents, were, shown to be inhibitors of acid corrosion. The higher the effective charge on the heteroatom, the more effective the inhibitors; the effectiveness increases in the presence of specifically adsorbing iodine ions.