Anodic behaviour of Zn0.5Al doped with molybdenum in acidic, neutral and alkaline media

The paper presents the results of a potentiodynamic study of the anodic behaviour of Zn0.5Al doped with molybdenum in the acidic (0.1 M, pH = 1; 0.01 M, pH = 2; 0.001 M, pH = 3), neutral (0.03, 0.3, 3%, pH = 7) and alkaline (0.001 M, pH = 10; 0.01 M, pH = 11; 0.1 M, pH = 12) media of HCl, NaCl and NaOH electrolytes. In the potentiodynamic mode with an electrode potential sweep rate of 2 mV/s, all Zn0.5Al-Mo samples containing from 0.01 to 1.0 wt% of molybdenum demonstrated a shift in the potentials of corrosion, pitting formation and repassivation. These potentials shift towards negative values in acidic and alkaline media, while shifting to positive values in a neutral medium. It was established that an increase in the concentration of electrolytes led to a shift of all the considered potentials towards negative values in all media - acidic, neutral and alkaline. This dependence is associated with the specific features of the process of anodic dissolution of alloys during the formation of an oxide film on their surface. The significance of the dependence of the stationary potential of free corrosion of alloys on time for establishing the passivity of surfaces in acidic, neutral and alkaline media was shown. It was determined that zinc alloys doped with molybdenum are resistant to pitting corrosion in all the investigated media. This resistivity is particularly high in acidic (0.001 M), neutral (0.03%) and alkaline (0.001 M) media of HCl, NaCl and NaOH electrolytes. The favourable effect of molybdenum on both the anodic behaviour of Zn0.5Al and the overall increase in the corrosion resistance of alloys was demonstrated. In comparison with undoped Zn0.5Al alloys, the corrosion rate of alloys doped with molybdenum (0.01-1.0 wt%) is 2-2.5 times lower. The proposed compositions of Zn0.5Al-Mo alloys can be used as noncorrosive coatings for steel products.

Electrodeposition and Growth of Iron from an Ethylene Glycol Solution

The electrochemical reduction of iron (III) ions into zero-valent iron from a solution of ethylene glycol was accomplished. The kinetics and mechanism of the electroreduction process were investigated by cyclic and linear polarization techniques. The influence of temperature, potential sweep rate, and concentration of iron (III) ions on the electroreduction process was also studied. The observed values of effective activation energy revealed that the investigated electroreduction process is accompanied by mixed kinetics control. Moreover, the results of SEM and X-ray diffraction analysis confirmed the deposition of thin Fe films under the optimized conditions.

EFFECT OF CALCIUM ON THE ANODIC BEHAVIOR OF ALUMINUM CONDUCTOR ALLOY AlTi0.1 IN THE MEDIUM OF THE ELECTROLYTE NaCl

The article presents the results of an experimental study of the effect of calcium on the anodic behavior of the aluminum alloy AlTi0.1, in the medium of NaCl electrolyte. The study was carried out by the potentiostatic method in the potentiodynamic mode at the potential sweep rate of 2 mV / s. It is shown that the modification of the aluminum alloy AlTi0.1 with calcium promotes the displacement of the potentials of free corrosion, pitting formation, and repassivation to the positive range of values. The corrosion rate of the aluminum alloy AlTi0.1 when modified with 0.01-0.5 wt % calcium decreases by 10-17 %.

Development of the voltammetric method for the quantitative determination of bendazole hydrochloride

In connection with the wide field of application of bendazole hydrochloride in medicine and its use as a part of combined drugs, an assessment of the effectiveness of the novel dosage forms and the determination of pharmacokinetic parameters are required. For this purpose, it is necessary to obtain data on the concentration of the studied drug in biological fluids. The aim of this research is to develop a voltammetric method for the bendazole hydrochloride quantification. In the course of the study, the optimal electrolysis conditions were established: potential was –1.8 V, time 15 s, and potential sweep rate 50 mV/s. The opti-mum pH value for electrolysis of bendazole hydrochloride is 6–7. The proposed method is validated by tests: specificity and linearity, detection limit; the range of the procedure and its analytical precision were determined. Thus, the developed method can be used for the quantification of bendazole hydrochloride in pharmaceutical substances.

Anodic Dissolution of Non-Ferrous Metals in a Glycerate-Alkali Electrolyte

Studies have been conducted to assess the possibility of refining a lead collector containing precious metals, with the aim of obtaining lead using an economically viable technology. Studied the patterns of anodic oxidation of lead and impurities in alkaline-water-glycerate electrolytes, depending on the concentration of sodium hydroxide and glycerol in the electrolyte, the potential sweep rate.

Effects of Magnetic Field on Uneven Dissolution of Iron in Sulfuric Acid Solution with Chlorides

The effects of magnetic field on anodic dissolution and passivation of iron in a sulfuric acid solution with chlorides are investigated by electrochemical measurements and surface observations. In the anodic potentiodynamic polarization curve, the potential for the drastic current drop is not significantly affected by the potential sweep rate under 0 T, which moves in the negative direction with increasing potential sweep rate under 0.4 T magnetic field that is parallel to the working electrode surface. The uneven surface produced during the potentiodynamic polarization hinders the transition from active dissolution to passivation. The area fraction of the locally accelerated dissolution increases with prolonging polarization time at high potentials where the surface film precipitation-dissolution process is the rate-determining step for metal dissolution. Pretreatment under potentiostatic polarization at 0.4 T magnetic field produces an uneven surface that would result in unrecoverable electrochemical states after switching from 0.4 T to 0 T, depending on the applied potential. The positive-feedback mechanism for the magnetic field effect and the surface morphological effect is proposed. The results demonstrate the direct magnetohydrodynamic effect and its resultant uneven surface on the anodic behavior of iron.

Corrosion-electrochemical behavior of an aluminum conductive E-AlMgSi alloy (aldrey) with tin in the environment of NaCl electrolyte

The economic feasibility of using aluminum as a conductive material is explained by the favorable ratio of its cost to the cost of copper. In addition, one should take into account the factor that the cost of aluminum remains practically unchanged for many years. When using conductive aluminum alloys for the manufacture of thin wire, winding wire, etc. Certain difficulties may arise in connection with their insufficient strength and a small number of kinks before fracture. In recent years, aluminum alloys have been developed, which even in a soft state have strength characteristics that allow them to be used as a conductive material. One of the promising areas for the use of aluminum is the electrical industry. Conductive aluminum alloys type E-AlMgSi (aldrey) are representatives of this group of alloys and treats heat-strengthened alloys. They are distinguished by high strength and good ductility. These alloys with appropriate heat treatment acquires high electrical conductivity. The wires made from it are used almost exclusively for overhead power lines.In the work presents the results of the study of the anodic behavior of aluminum alloy E-AlMgSi (aldrey) with tin, in a medium electrolyte 0.03; 0.3 и 3.0% NaCl. A corrosion-electrochemical study of alloys was carried out using the potentiostatic method on a PI-50-1.1 potentiostat at a potential sweep rate of 2 mV/s. It is shown that alloying E-AlMgSi (aldrey) c with tin increases its corrosion resistance by 20%. The main electrochemical potentials of the alloys when doping with tin are shifted to the positive range of values, and from the concentration of sodium chloride in the negative direction of the ordinate axis.

INFLUENCE OF ALKALINE – EARTH METALS ON ANODIC BEHAVIOR OF ALLOY ССУЗ IN NEUTRAL ENVIRONMENT OF THE ELECTROLYTE NaCl

The anodic behavior of a lead-antimony alloy (3 wt% Sb) doped with alkaline-earth metals was investigated in potentiostatic method in the potentiodynamic mode at a potential sweep rate of 2 mV/s and it was shown that with an increase in the content of alkaline earth metals in the alloy (SSUZ), the potentials of free Corrosion and pitting are slightly shifted to the positive region. As the concentration of the chloride ion in the electrolyte increases, these potentials decrease. The current density of corrosion and, accordingly, the corrosion rate of alloys with an increase in the content of alkaline earth metals are reduced by 75–85%, and the concentration of chloride ion increases.In transition from alloys with calcium to alloys with strontium, the corrosion rate of alloys increases by 20–30%, and to alloys with barium it decreases by 25–30%.

Growth of Ultra-thin Titanium Dioxide Films by Complete Anodic Oxidation of Titanium Layers on Conductive Substrates

ABSTRACTThe growth of thin and ultra-thin titanium dioxide layers was investigated. Oxide films were grown by galvanostatic and potentiodynamic anodisation of evaporated titanium layers on conductive substrates. It is shown that thin-film oxidation differs significantly from anodic oxidation of solid foils or plates, due to the sudden stop of anodisation process before complete oxidation of the thick films. Depending on the pH value and the potential sweep rate, the effective defect density and the dielectric constant of the anodized layers vary from 3·1019 cm-3 to 1020 cm-3and from 16 to 27, respectively, whereas the electrolyte temperature plays only a minor role.