Zinc alloy coatings electrochemically deposited on steel from electrolytes with different components differ in their composition, homogeneity, porosity, structure and other characteristics that affect their corrosion resistance. Manganese is characterized by a very negative electrochemical potential and very high strength, prompting many researchers to study Zn-Mn alloys for the anti-corrosion purposes in the industry, especially automotive. In this work it was examined the influence of the type of the electrolyte deposition on the current efficiency during electrodeposition of Zn-Mn alloys. Zn-Mn alloys were deposited on steel from chloride, sulphate and pyrophosphate plating baths at different current densities. We have examined the influence of deposition current density on the current efficiency during electrodeposition, appearance of alloy coatings, as well as their corrosion stability. It was shown that Zn-Mn alloys with the best corrosion properties, among all examined ones, were obtained from chloride plating bath at 2 A dm-2 .
Technological properties of powders depend on their granulometry and morphology. Very often one method is inadequate for characterization of powder particles. This article studied different methods intended for clear definition of the copper powder granulometric and morphological properties. Quantitative microstructural analysis, sieve analysis, and XRD analysis of copper powder as well as scanning electron microscopy analysis of the copper powder particles were performed. It was determined that selected stereological parameters, such as area, perimeter, and shape factor (roundness) show a linear decreasing dependence of current density, while the morphology was changed from massive to branched 3D dendrites. XRD analysis indicated that the crystallite sizes shows a linearly increasing dependence on current density. The shape factor could be a useful parameter for description of powder morphologies deposited by different regimes.
Electrochemically deposited Zn-Ni-Co alloys under various deposition conditions were investigated using atomic absorption spectroscopy for the determination of the chemical composition, atomic force microscopy for surface morphology analysis, and electrochemical impedance spectroscopy for determination of corrosion properties. The influence of the ratio of the alloying elements, [Co 2+ ]/[Ni 2+ ], in a chloride deposition solution, as well as the deposition current density, on the chemical content, morphology and corrosion properties of the ternary alloys was studied. The plating solutions used were with the same overall metal concentration, free of additives and the deposition was realized at room temperature. It was shown that the deposition of the ternary alloy coatings was of anomalous type and that the ratio of nickel to cobalt ions in the plating solution, as well as the deposition current density, had a significant influence on the chemical composition and corrosion stability of these coatings. The presence of both Ni and Co was beneficial for their corrosion stability. It was shown that morphology and porosity were important factors in the corrosion stability of these coatings. The coating deposited from the solution with higher [Co 2+ ]/[Ni 2+ ] ratio at 8 A dm -2 was made up of the smallest crystalline aggregates, had a small surface roughness and porosity, and was with quite uniform distribution of agglomerates and it exhibited the best corrosion stability.
The inhibiting action of a nonionic surfactant of the TRITON-X series (TRITON-X-405) on stainless steel type X4Cr13 in 1.0 M H 2 SO 4 solution within the temperature range of 25À45 °C was studied using the gravimetric and potentiodynamic technique. The inhibition efficiency was found to increase with the inhibitor concentration and decrease with temperature. The satisfactory inhibition efficiency of TRITON-X-405 on SS type X4Cr13 in 1.0 M H 2 SO 4 was limited to temperatures below 35 °C or at the surfactant concentration higher than c = 10 À5 M. The adsorption of TRITON-X-405 on stainless steel type X4Cr13 in one molar of sulphuric acid within the chosen temperature range follows the FloryÀHuggins adsorption model with very high negative values of the free energy of adsorption ΔG ads . The thermodynamic parameters, such as the heat of adsorption and adsorption entropy, were calculated by employing thermodynamic equations. Activation parameters such as apparent activation energy, activation enthalpy, and activation entropy were evaluated from the effect of temperature on corrosion and inhibition processes. Those entire apparent activation parameters show an increaseÀdecrease characteristic (a nonmonotonic function). They increased at concentrations lower than the cmc of added surfactant and decreased when the concentration of TRITON-X-405 was higher than c = 10 À5 M.
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