Technical Physics Letters

Belova, O. S.; Bolotov, D. V.; Kazantsev, S. Yu.; Kivshar, T. K.; Lysov, N. Yu.; Miloserdov, A. I.; Temnikov, A. G.

doi: 10.1134/s1063785025600048pmid: N/A

The effect of atmospheric electricity on the operation of fiber-optic communication lines has been studied on an electrophysical installation designed to simulate lightning in laboratory conditions. The change in the polarization state of the linearly polarized radiation transmitted over a fiber-optic cable has been measured using a high-speed polarimeter. During the experiments with a frequency of 100 MHz, a change in the polarization state has been monitored. For the first time, rapid rotations of the plane of polarization, the formation of elliptical polarization, and changes in the angle of ellipticity when exposed to atmospheric discharges on an optical cable have been recorded with precise reference. The effect of maintaining the radiation polarization state when the high voltage is turned off at an electrophysical installation has been discovered.

Grishin, Yu. M.; Khandramay, N. A.

doi: 10.1134/s1063785025600231pmid: N/A

The results of numerical 3D modeling of freely convective heat-exchange processes in the channels of one of the main variants of a panel-radiant room-heating system with a ribbon finning system have been presented. The spatial distributions of the thermophysical parameters of free-convective air flows have been determined both in the internal and external regions of the system in wide ranges of changes in the basic operating and geometric parameters of the BS. The features of the behavior of the heat-transfer coefficients from the BS heating surfaces to the updraft have been calculated and established. The criterion dependences for calculating the Nusselt numbers on the modified Rayleigh number and other parameters of the vertical channels of the baseboard system have been proposed. A formula for calculating the specific heat removal capacity from the heating surfaces of the system’s internal elements has been obtained. It has been shown that the specific heat-removal capacity nonmonotonously depends on the ratio of the lengths of intercostal gaps in adjacent channels, at certain values of which there is an extremum. The relations between the capacities of convective and radiative heat fluxes generated in the considered heat-exchange system have been established. Recommendations on the choice of basic geometric and operating parameters that can provide an increase in heat removal by 20–30% compared to the practical BSs with a belt finning system have been given.

Kravchenko, I. N.; Kuznetsov, S. N.; Velichko, S. A.; Temasova, G. N.; Martynov, A. V.

doi: 10.1134/s1063785025600401pmid: N/A

The possibility of use of air plasma spraying for depositing thick wear-resistant coatings when restoring brass parts in heavily loaded friction units is demonstrated. Recommendations for reducing the consumption of nonferrous metals and the coefficient of friction and increasing the service life of restored products are given.

Kuznetsov, Yu. A.; Dobychin, A. V.; Yakovlev, D. D.; Gribakin, A. A.; Pichev, V. S.; Kravchenko, I. N.

doi: 10.1134/s1063785025600498pmid: N/A

The results of study of the adhesive strength of coatings formed by supersonic flame spraying from different powder materials are reported. The adhesive strength of the coatings has been evaluated by the adhesive method. It has been found that, in most cases, the experimental samples have been destroyed along the adhesive layer. The maximum adhesive strength of the investigated coatings is 72.8–101 MPa, depending on the type of a sprayed powder. The proposed powder materials are recommended for use in repair works for restoring operating surfaces of worn machine parts.

Uvarov, K. F.; Molchanov, A. M.

doi: 10.1134/s1063785025600097pmid: N/A

Optimization parameters of a cyclic thermal de-icing system (DIS) are formulated. A method of optimization multiparametric calculation has been developed. The use of this technique is proposed in the conditions of the most intense icing of the structure in question to determine the best operating parameters of the de-icing system. The use of the obtained parameters reduces the DIS’ energy consumption, which can reduce the weight of the batteries powering it and increase the efficiency of both aircraft and wind turbines in icing conditions.

Paizullakhanov, M. S.; Parpiev, O. R.; Nodirmatov, E. Z.; Bazarova, M. Kh.; Shosaitov, Sh. Sh.

doi: 10.1134/s1063785025600061pmid: N/A

It has been shown that a material based on sodium ferrate NaFeO2 can be obtained by synthesis from a melt in a solar furnace. The crystal structure is tetragonal with the lattice parameters of a = 5.638 Å, b = 5.672 Å, and c = 7.279 Å. The average particle size of the material is 1.2 μm. It has been found that the NaFeO2 material sample provides the oxidation–reduction activity of Na+/Na and the oxidation–reduction activity of Fe2+/Fe3+. Therefore, NaFeO2 can be a potential material for the cathode of a sodium-ion battery with a specific capacity of 110 mAh/g. It has been found that sodium ferrate NaFeO2 exhibits sufficiently good resistance to water. That is, sodium ferrate does not decompose in water at 80–100°C.

Sitnikov, S. A.; Butusova, O. A.; Bulychev, N. A.

doi: 10.1134/s1063785025600279pmid: N/A

The work is aimed at creating new scientifically proven technical and technological solutions for the development and implementation of additive manufacturing of products from heat-resistant reinforced composites allowing samples to be created of new equipment and structural products for the aerospace industry surpassing existing analogues in their properties. Samples of the binder used to obtain composites were studied. Studies were carried out using IR spectroscopy with Fourier transform, and a comparison of the bands of stretching and deformation vibrations of the studied sample and classical polydimethylsiloxane was carried out. The dry residue after combustion of the sample was studied using transmission electron microscopy. It was shown that the sample is polydimethylsiloxane filled with silicon dioxide. Chromatograms and molecular-weight characteristics of polydimethylsiloxane were obtained. The soluble part of the sample was no more than 35% in the case of using benzene and tetrahydrofuran as solvents.