卷 54, 编号 3 (2018)

The electrochemical doping of coatings with metals and nonmetals is discussed. Using the examples of the electrodeposition of zinc–chromium and nickel–phosphorus coatings, it has been shown that the presence of donors of the electrodeposited coating components in the inner sphere of a heteronuclear or heteroligand complex contributes to their coreduction and the formation of an alloy. The composition, morphology, and properties of the coatings have been characterized. It has been shown that the corrosion resistance of the zinc–chromium coatings is two times higher than that of the zinc coatings. After storage, the nickel–phosphorus coatings preserve their solderability with low-temperature solders.

The influence of orientation of a discharge channel in water and the length of a cylindrical discharge chamber on the kinematic characteristics of the maximum deflection of plates during molding into an open ring matrix have been studied experimentally. The optical method is used to measure the deflection of the plate deformed by pressure waves generated by an electric discharge in water. No significant effect of the discharge channel orientation and relative length of the cylindrical discharge chamber on the plate deflection is detected.

The thermoelectric properties and Shubnikov–de Haas (SdH) oscillations of monocrystalline layers of a topological insulator (ТI) of n-type bismuth telluride were investigated. The monocrystalline Bi₂Te₃ layers were fabricated by the mechanical exfoliations of layers from a monocrystalline ingot of the appropriate composition. The cyclotron effective masses, the Dingle temperature, and the quantum mobilities of charge carriers were calculated from the experimental data by SdH oscillations both in longitudinal (H ║ I) and in perpendicular (H ⊥ I) magnetic fields at temperatures in the range of 2.1–4.2 K. It was found that the phase shift of the Landau levels index is 0.5 both for the parallel and for the perpendicular magnetic fields associated with the Berry phase of surface states. The power factor in the temperature range of 2–300 K was calculated from the temperature dependences of resistance and thermal e.m.f. It was stated that the power factor α²σ has a maximum value in the temperature range of 100–250 K, which corresponds to the maximum values for perfect monocrystals described in the literature. Taking into account that the heat conductivity in the thin layers is essentially lower than in the bulk samples, it is reasonable to expect a considerable increase in the thermoelectric efficiency over a wide temperature range, which is of great importance for the development of new highly effective thermoelectric materials based on thinner Bi₂Te₃ ТI layers for practical applications in thermogenerators and coolers.

A new compound 2-(4-(diethylamino)-2-hydroxybenzyledene) hydrazinecarboamide (DHBHC) was prepared by the condensation of thiosemicarbazide and diethylaminosalicyaldehyde in ethanol–water mixture and its purity was confirmed with IR, H¹ and C¹³ NMR. Anticorrosion properties of this new compound were studied on the aluminium alloy AA2024-T3 in 0.5M HCl solution at 303 K by potentiodynamic polarization, electrochemical impedance spectroscopy and weight loss method. The inhibition efficiency of DHBHC was found to increase with an increase of its concentration. The inhibition efficiency obtained in this study was 96 ± 3% in the presence of 10 × 10^‒5 M of DHBHC. The surface morphology of the alloy was investigated both in the presence and in the absence of the inhibitor by field emission scanning electron microscopy, 3D profilometry and X-ray photoelectron spectroscopy.

The protection of carbon steel in the presence of three cationic Schiff bases and their copper and cobalt complexes in 0.5 M H₂SO₄ was investigated in terms of corrosion inhibition efficiency using weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The results showed high corrosion inhibition efficiency of the inhibitors and their metal complexes. The inhibition efficiency was raised by increasing the inhibitors concentration. From polarization curves, the inhibitors act as mixed type ones. The EIS spectra exhibit a large capacitive loop at high frequencies followed by a large inductive one at low frequencies.

The current−voltage characteristics and the resistivity of composite resistors (varistors) based on a nonpolar polyethylene and bentonite (a clay mineral) were investigated. It was found that the content of composite components influences to the current−voltage characteristics and the magnitude of resistivity. It was shown that when increasing the molar content of the filler, the magnitude of resistivity decreases exponentially.