ELEKTRONNAYA OBRABOTKA MATERIALOV

Increasing of Wear Resistance of Heat-Resistant Nickel Alloy Using Anodic Plasma Electrolytic Treatment

2025-07-02T14:45:55+03:00

UDC 544.558+66.088

DOI https://doi.org/10.52577/eom.2025.61.3.01

A possibility of the plasma electrolytic treatment of a heat-resistant nickel alloy ChN77TiAlB, which leads to the removal of edge cracks, a decrease in hardness and an increase in wear resistance, is shown. The volt-ampere and volt-temperature characteristics of the plasma electrolytic treatment, typical for anodic processes, are revealed. Changes in the morphology and roughness of the surface, the structure and microhardness of the surface layers are considered. It was established that the treatment in an electrolyte based on carbamide and ammonium chloride leads to the formation of nitrocarburized layers without the formation of compounds. The combined effect of both high-temperature oxidation and anodic dissolution on the morphology and roughness of the surface was determined. Tribological tests were conducted using the ball-on-disk scheme, which showed the best results after treatment at 900 °C (reduction in volumetric wear by 15.7 times), when a reduction in roughness (by 5 times) and the presence of thick oxide layers determine a uniform running-in period, reaching a lower value of the friction coefficient, and homogenization of the alloy, accompanied by the removal of cracks, determines a softer wear mechanism. Positive results were obtained in abrasive wear tests: after treatment at 600 and 900 °C, volumetric wear decreased by 2.6 and 2.2 times, respectively.

Keywords: heat-resistant nickel alloy, plasma electrolytic treatment, microhardness, surface roughness, wear resistance, friction coefficient.

Structure, Mechanical and Corrosion Properties of Coatings Based on ZrN Solid Solution

2025-07-02T16:29:35+03:00

UDC 67.017

DOI https://doi.org/10.52577/eom.2025.61.3.12

The structure, elemental composition, mechanical and corrosion properties of (Zr, Nb)N, (Zr, Hf)N and (Zr, Nb, Hf)N vacuum-arc coatings deposited on the titanium alloy Ti-6Al-4V were studied. The X-ray diffraction analysis, scanning electron microscopy, microhardness measurement, adhesion and corrosion tests were used as investigation techniques. It was found that the coatings were single-phase solid solutions based on ZrN. The highest microhardness value (17 GPa) was observed for the (Zr, Hf, Nb)N coating, and the lowest value (9 GPa) – for the (Zr, Nb)N coating. The (Zr, Hf)N coating also possessed the highest critical force Lc3 during scratch tests. Comparison with the data obtained earlier showed that a decrease of the Nb concentration in the (Zr, Nb)N coating and an increase of the Hf concentration in the (Zr, Hf)N coating led to the growth of the critical force Lc3. Corrosion tests carried out in a 3% NaCl solution in the galvanostatic mode showed that the (Zr, Nb)N coating maintained continuity over the entire surface of the alloy in contrast to the coatings containing Hf atoms.

Keywords: titanium alloy, biomedical implants, nitride coatings, adhesion, microhardness, corrosion.

Electrochemical and Corrosion Behavior of Ni-Re Alloys and Their Components

2025-07-02T16:52:52+03:00

UDC 621.9.047.7:669.018.8

DOI https://doi.org/10.52577/eom.2025.61.3.24

The comparative corrosion resistance and electrochemical behavior of the deformed and annealed Ni-Re alloys and their components in acidic, alkaline, and neutral media was investigated. Nickel alloying with rhenium leads to sharp strengthening of the solid solution both in the deformed and in the annealed state. However, at the same time, the corrosion resistance of an alloy in 48% H₂SO₄ decreases, but increases in the concentrated HCl and HNO₃. The diffusive-migration nature of limiting current of alloys at anode polarization in NaCl solutions was established (as well as at dissolution of Ni and Co). The deformed metals are less resistant than annealed ones in all media.

Keywords: corrosion resistance, nickel-rhenium alloys, deformed alloy, annealed alloy, tests in aggressive media.

Effect of Gamma Irradiation on the Electrophysical Parameters of Nickel-Doped Silicon Grown by the Czochralski Method

2025-07-02T17:04:23+03:00

UDC 621.315.592

DOI https://doi.org/10.52577/eom.2025.61.3.38

The effect of γ-irradiation on the electrophysical parameters of silicon doped with nickel during growth from melt according to the Czochralski method was studied. Experimental results obtained by the scanning electron microscopy showed that clusters of Ni atoms ~ 6÷8 μm in size with a surface density of ~ (5÷8) × 10³ cm^-2 were formed in nickel-doped silicon during cultivation. It was established that during irradiation with γ-quanta ⁶⁰Co of the control samples not doped with nickel, material compensation occurs due to the generation of deep centers of radiation origin. In silicon samples doped with nickel, when irradiated with γ-quanta, the size of the clusters decreased, and the concentration of free charge carriers changed slightly: when the fluence increased to Ф ≥ 3∙10⁸ rad, and the resistivity decreased by no more than 30%. Such a change in the parameters of Si < Ni > samples is due to the formation of acceptor centers because of an increase in the concentration of electrically active nickel atoms. It was shown that during irradiation nickel atoms diffuse from clusters into the silicon matrix, where upon interaction with radiation-generated vacancies interstitial nickel atoms Ni_i pass into electrically active position in the Ni_s crystal lattice unit. Those impurity defect centers (Ni_s) were thermally stable to at least an annealing temperature of 600 °C.

Keywords: γ-irradiation, clusters, nickel, doping, silicon.

Methodology for Designing an Ultrasonic System for Thermosonic Wire Ball Bonder

2025-07-02T17:17:30+03:00

UDC 621.791.16

DOI https://doi.org/10.52577/eom.2025.61.3.45

A methodology for designing an ultrasonic system is proposed, which provides the stability of thermosonic gold wire bonding with a diameter of 17.5–50 μm during the assembly of electronics devices in cermet. Modeling of the waveguide was carried out at the standard frequency of ultrasound of 66 kHz and an increased frequency of 136 kHz.

Keywords: wire bonding, cermet circuit packaging, ultrasonic/thermosonic micro bonding, ultrasonic transducer, transducer horn, sound speed, bonding capillary.

Control of Electron Localization in Pentameric Nanoclusters of Various Configurations in an External Electric Field

2025-07-02T17:24:44+03:00

UDC 538.9+539.1.01+539.189

DOI https://doi.org/10.52577/eom.2025.61.3.52

A minimal theoretical model for describing the dynamics of localization of a shared electron in a pentamer nanocluster in an external low-frequency electric field, taking into account the electron-vibrational interaction, is proposed. Based on the given model, the system of differential equations was obtained regarding the time dependences of amplitudes of the probability of finding an electron on different centers of a pentamer. This model was used to describe the pentamers of linear and square-planar configurations. For those two types of the pentamer configuration, the numerical calculations were performed at different values of model parameters. The proposed model is characterized by the fact that the centers of the nanocluster are considered as weakly tunnel-coupled, and the electron-vibrational coupling with the ligand environment on each of its centers plays a significant role. Moreover, tunneling is taken into account only between the nearest centers of the nanocluster while the cluster centers are considered equivalent. The control role of an external electric field was revealed so that the variations of its amplitude and frequency allowed to realize the various electron localization regimes in the pentamer nanocluster. By setting up the values of those electric field parameters, the duration of the full localization of an electron at a certain cluster center (or centers) was regulated, as well as the rate of switching the localization of an electron to another cluster center (or centers), and the overall distribution of electron density in the nanocluster.

Keywords: pentamer nanocluster, ligand environment, electron-vibrational interaction, low-frequency electric field, electron localization.

Synchronization and Symmetrization of the Main Voltages of Transformer-Based Power Electronic Converters in the Overmodulation Zone of Voltage Source Inverters

2025-07-02T17:31:57+03:00

UDC 621.314.572

DOI https://doi.org/10.52577/eom.2025.61.3.61

This article discusses the features of the synchronous regulation of inverter blocks of two topologies of the transformer-based photovoltaic installations based on two and three three-phase voltage source inverters operating in a specific over-modulation zone characterized by increased, close to maximum values, modulation indices of inverters. It is shown that, in the case of a two-range inverter control strategy in the over-modulation mode, the modified algorithms of a synchronous pulse-width modulation, including the use of specialized correction coefficients for each sub-range of the over-modulation zone, allowed for the continuous synchronization and symmetry of the basic voltage waveforms on the inverter-side windings of the power transformer of photovoltaic systems throughout the entire inverter over-modulation zone. The results of modeling the processes in the systems confirm the fact of the absence of harmonic components of even-order and subharmonics (of the fundamental frequency of photovoltaic stations) in the spectra of the basic voltages of the analyzed photovoltaic installations over the entire range of two-stage regulation of inverters in the over-modulation zone. Such an improvement in the harmonic composition of the basic voltages leads to a decrease in losses and an increase in the efficiency of the functioning of photovoltaic installations based on inverters with synchronous modulation, which is especially important for high-power systems characterized by a relatively low switching frequency of the power switches of the inverters.

Keywords: three-phase voltage inverter, synchronous pulse-width modulation, photoconverter installation, multi-winding power transformer, harmonic composition of voltage.