bluuebunny/crossref_metadata_2025_split huggingface dataset:
ESTIMATION OF GAS-DYNAMIC PARAMETERS AT THE EXIT OF THE IMPELLER DURING MODERNIZATION OF MI-2MSB FAN INSTALLATION
Authors: Tatarchuk T. , Kravchuk Yu. , Pelukh V. 
Published: January 2023

Purpose. Analysis of methods to increase the efficiency of the cooling system of theAI-450M engine units of the Mi-2MSB helicopter and evaluation of gas-dynamic parameters at the impeller outlet, fan installation MI-2MSB
Research methods: finite element method (FEM).
Results. It was shown that the use of a centrifugal fan as the main element in the system of air injection, cabin air conditioning and cooling systems and engine units provide the following opportunities and improvements:
- at constant speeds and without changes in the transmission system to increase the amount of running air by 200…300 %;
- reduce the temperature of heated units to the values recommended by the operation manual;
- to increase the service life of complex-loaded elements of the system of connection of free turbine shafts with the shaft of the main gearbox;
- reduce the risk of accidents due to poor air conditioning in the cockpit and passenger seats.
The analysis of possible types of C.S modernization was carried out, the estimated estimation of gas-dynamic parameters at the exit of the impeller - to the sub-radiator space was carried out. The problem was solved by changing the type of impeller from axial to centrifugal.
Scientific novelty. The problem of creating an efficient and reliable cooling system for internal systems and units of the Mi-2MSB light multi-purpose aircraft, which has been modernized with the replacement of old GTD-350 engines with newer ones, AI-450 series - urgent, in the absence of similar light helicopters of domestic production. An important component of the safety and reliability of all components of the helicopter is to maintain the correct thermal regime of its components.
Practical value. The obtained results are important in the further process of production and modernization of the Mi-2 helicopter of all modifications with the latest engines, as well as for helicopter development projects in Ukraine - SME-2 “Hope”, SME-6 “Otaman”, SME-8 and others. The ability to increase cooling efficiency, air conditioning and reduce engine load increases the life, reliability of components and improves comfort and performance for pilots and passengers.
DETERMINATION OF ENERGY PARAMETERS OF Ni+Al2O3 POWDER PARTICLES IN A SUPERSONIC NOZZLE DURING COLD GAS-DYNAMIC SPRAYING USING THE ANALYTICAL METHOD
Authors: Shorinov О. , Polyvianyi S. 
Published: January 2023

Purpose. To calculate the temperature and velocity of nickel and aluminum oxide particles in the supersonic flow in the low-pressure cold gas-dynamic spraying nozzle. To investigate the effect of gas parameters at the nozzle inlet, in particular temperature and pressure, on the velocity and temperature of particles at the nozzle outlet.
Research methods. The calculation of the temperature-velocity characteristics of the powder particles is performed after determining the parameters of the gas flow in the supersonic nozzle channel using well known gas-dynamic dependencies. The initial data for the calculation are the following: the geometry of the nozzle, the temperature and pressure of the gas (air) at the nozzle inlet. The density of the material from which particles are obtained, as well as their diameter, were taken into account in the calculation of the energy parameters. Nickel particles with a diameter of 25 µm and aluminum oxide particles with a diameter of 22 µm were used.
Results. Based on the calculations results, graphs of changes in the velocities and temperatures of the particles of the investigated powders, as well as working gas, in the channel of the low-pressure cold gas-dynamic spraying supersonic nozzle were developed. The dependences of the temperature-velocity parameters of the particles at the nozzle exit in the range of initial values of temperature at the nozzle inlet from 300 to 600 C° and pressure from 0.6 to 1.0 MPa were also developed.
Scientific novelty. The influence of the initial parameters of the gas at the nozzle inlet in a wide range of values on the temperature and velocity of nickel and aluminum oxide particles during the low-pressure cold gas-dynamic spraying is shown.
Practical value. The obtained results can be used to determine rational spraying parameters in the development of technological processes of deposition of protective and restorative coatings from Ni+Al2O3 powder mixture.
INFLUENCE OF THE CHEMICAL COMPOSITION OF HIGH-CHROMIUM CAST IRON ON THE CONTENT OF CHROMIUM IN NEAR-CARBIDE ZONES AFTER ANNEALING AT 720 °С
Authors: Netrebko V. 
Published: January 2023

Purpose. Increasing the corrosion resistance of wear-resistant high-chromium materials operating in a liquid abrasive environment makes it possible to increase the service life of products made from these materials, which is an important task in materials science. One of the main reasons for the occurrence of damage during corrosion processes is the uneven distribution of chromium in the metal base, which leads to the formation of microgalvanic pairs on the surfaces of parts in an electrolytic environment. The creation alloys of wear-resistant high-chromium, in the metal base of which microgalvanic vapors are not formed, is a promising direction for increasing the corrosion resistance of such materials. Investigation of chromium distribution processes after heat treatment parts of high-chromium cast iron, namely the formation of metal base zones near carbides.
Research methods. Analytical review of publications. Metallographic, microstructural and local X-ray microanalysis. Mathematical modeling of processes.
Results. It was revealed that during the heat treatment in high-chromium cast irons, structures with significant segregation of chromium are formed. It has been established that after annealing of castings at 720 °C, the minimum chromium content in the metal base is observed in the zones near carbides, and the maximum in the central zones of the graids. The presence zones with a chromium content of more than 12 % (positive potential) and less than 12 % (negative potential) leads to the formation of microgalvanic couples, which is the main reason for the acceleration of corrosion damage in the metal base. The dependence of the chromium content in the zones near the carbides after annealing at 720 °C on the chemical composition of cast iron has been determined.
Scientific novelty. The mathematical model is proposed for determining the chromium content in the zones near carbides after annealing at 720 °C with an exposure of 9 hours from the chemical composition of cast iron in the Fe-C-Cr-Mn-Ni system. This makes it possible to predict the chromium content in the zones near the carbides and prevent the formation of microgalvanic pairs.
Practical value. The dependence (mathematical model) obtained can be used in the development of compositions of high-chromium wear-resistant cast irons with increased corrosion resistance and machinability.
ON THE INTERACTION OF ALLOYING ELEMENTS WITH GRAIN BOUNDARIES OF HIGH-PURITY NICKEL AND IRON
Authors: Ol’shanetskii V. , Stepanova L. , Kononenko Yu. , Skrebtsov А. 
Published: January 2023

Purpose. Proof of the reality of the effect of displacement of some microadditives from the internal boundaries of the grains into their internal volumes for reasons of purely thermodynamic concepts.
Research methods. The initial data were specially selected chemical compositions of model alloys based on high-purity nickel and iron, which are microalloyed with yttrium, lanthanum, zirconium and rhenium. The choice of nickel and iron as the basis for the alloys under study is due to the fact that they are the base for a large group of industrial alloys (heat-resistant nickel materials and a wide range of steels for various purposes).
The lattice parameters of nickel and iron were determined using an improved DRON-1 type diffractometer in copper (nickel alloys) and iron (iron alloys) X-ray radiation with monochromatization of diffracted beams. The lattice parameters were determined, respectively, using the (420)a and (220)a lines, respectively, for nickel and iron alloys.
Results. During recrystallization, migrating grain boundaries in nickel and iron retain impurity atoms and still partially “sweep” them out of the grain volume. The thickening of the boundary zones (that is, their "loosening") prevents the possibility of supersaturation of the interfaces with microalloying impurities.
The effect of significant displacement of some microalloying elements (zirconium and rhenium) deep into the grains of the matrix phases (nickel and iron) has been established.
It has been found that such microalloying elements as lanthanum (cerium) and yttrium have the most effective influence on the strength characteristics of the studied metallic materials.
Scientific novelty. Graphs of changes in the chemical composition of microalloyed basic solutions (nickel and iron) are plotted while maintaining the fine structure of grain boundaries. If they are loosened, this crowding out effect disappears.
Practical value. Since the effect of microalloying (as shown in the presented works) significantly affects the strength characteristics of materials, the results of the study showed which of the selected microalloying elements act most effectively in this direction.
RELATION BETWEEN DISCONTINUOUS PLASTIC FLOW AND STRAIN HARDENING OF THE LOW-CARBON STEEL
Authors: Vakulenko I. , Plitchenko S. , Bolotova D. , Perkov O. 
Published: January 2023

Purpose. Determination of the conditions for the disappearance of a section of intermittent flow and its effect on the strain hardening of low-carbon steel.
Actuality. The use of low carbon steels with intermittent flow for stamping has a significant limitation. Based on this, the issues of the effect of ferrite grain size on the occurrence of intermittent flow are relevant for determining the optimal structural state of steels intended for deep drawing.
Research methods. The structure of the samples was studied under a light microscope, the grain size of the ferrite was determined by the methods of quantitative metallography. The mechanical properties of steel were determined in tension at room temperature and a strain rate of 10-3 s-1. The characteristics of the initiation of plastic flow and the parameters of strain hardening were determined from the analysis of tension curves in logarithmic coordinates. In the region of uniform strain hardening, the deformation of the violation of the directly proportional relation lgσ-lgε was determined as the moment of formation of dislocation structures with a certain periodicity.
Results. An increase in the grain size of ferrite is accompanied by a decrease in the region of intermittent flow and a shift in the moment of formation of a dislocation cellular structure towards small plastic deformations. The strain hardening rate in the region of uniform work hardening and the Lüders strain are related by an inversely proportional relationship. With excessively large grain sizes of ferrite, the difficulty of maintaining conditions for a uniform distribution of slip lines is one of the reasons for the disappearance of the intermittent flow region on the deformation curves of low-carbon steel.
Scientific novelty. With an increase in the grain size of ferrite, the deformation of the beginning of the decay of a uniform distribution of dislocations into periodic structures is shifted to a decrease. At the same time, an increase in the ability of the metal to work hardening during the formation of a deformation band contributes to a decrease in the length of the intermittent flow section.
Practical value. Determining the nature of the influence of the grain size of low-carbon steel ferrite on the characteristics of work hardening and the formation of dislocation periodic structures can be useful in determining the optimal structural state of steel for deep drawing.
DETERMINATION OF THE OPTIMAL PARAMETERS OF LASER BORIDING TO IMPROVE THE WEAR RESISTANCE OF PISTON RINGS
Authors: Glushkova D. , Volchuk V. 
Published: January 2023

Purpose. The goal was to determine the effect of laser heating parameters on the structure and depth of the borated layer, since the properties of piston rings depend on the depth of the latter.
Research methods. Microstructural and X- ray phase analyzes were used to determine the structural state of piston rings.
Results. Application of traditional boriding methods associated with diffusion of boron into the solid phase leads to formation of the working layer having high brittleness. The conducted studies revealed that the increase in the speed of displacement of the part in the process of laser heating reduces the depth of the borated layer. Such a dependence is observed both at 0.15 mm thickness of coating and at a thickness of 0.30 mm. For all modes of workpiece displacement speed for the used boron containing envelope with the above-specified thickness a higher thickness of the borated layer and the heat affected area corresponds to a higher thickness of coating. Increase of the spot size leads to an increase in the depth of the layer. By X- ray and metallographic diffraction there were decoded the phases and structural constituents of the borated layer.
Scientific novelty. An approach to solving the problem of increasing the wear resistance of piston rings without crumbling is shown. The use of laser heating during drilling ensures the formation of a new layer with special properties. However, optimal properties can be achieved only after establishing a relationship between the parameters of the process and the depth of the boron layer. X-ray and metallographic analysis determined the relationship between the rate of irradiation and the proportion of high-boron structures in the layer. It is shown that the borated layer in high-strength cast iron contains such phases as FeB, Fe2B, α- phase, borocementite Fe3(B,C).
Practical value. Increased wear resistance of piston ring materials, which often limits the growth of machine productivity and their service life. Research results can be extended to other parts subject to intensive wear.
Influence of high-temperature treatment conditions on the structure and tribological properties of a nickel-based laser clad coating
Authors: Soboleva N. N. , Makarov A. V. 
Published: January 2023

Laser cladding featuring by a minimal thermal impact on the substrate is an advanced method of restoring the working dimensions of parts operated under wear conditions. Ni–Cr–B–Si system coatings can be used in parts operated at high temperatures. The research was aimed to study the influence of heating and subsequent cooling conditions during high-temperature treatment on the structural phase state formation features of the coating obtained by PG-SR2 powder laser cladding (chemical composition, wt.%: 14.8Cr; 2.1B; 2.9Si; 2.6Fe; 0.48C; the rest is Ni), and properties achieved in this process (hardness and tribological properties when sliding on the fixed corundum abrasive). Samples with the clad layer were heated at 1050 °С (holding for 1 h) with subsequent cooling in water (which made it possible to record structural transformations under high-temperature heating), in air, in a muffle furnace and in a vacuum furnace. It was shown that the cooling rate during the high-temperature treatment of the laser clad PG-SR2 coating has a significant effect on the formed structure and properties. High-temperature heating leads to a partial diffusive dissolution of Ni3B nickel borides and Cr23C6 chromium carbides in a solid solution and a corresponding decrease in hardness, an increase in abrasive wear intensity and friction coefficient. Cooling rate deceleration from 1050 °C when samples are cooled in air, muffle and vacuum furnaces leads to the release of CrB chromium borides and Ni3Si nickel silicides that were absent in the clad coating structure. High-strength CrB borides with hardness equal to or even higher than that of the corundum abrasive limit the development of the microcutting mechanism during abrasive wear. Large chromium carbides and borides formed during slow cooling in the furnace form wear-resistant frame-like structures. This leads to an increase in hardness and abrasive wear resistance to levels that exceed the features of the original clad coating.
Structure and properties of AL–Cu–Yb alloy with iron and silicon impurities
Authors: Barkov M. V. , Mamzurina O. I. , Glavatskikh M. V. , Barkov R. Yu. , Pozdniakov A. V. 
Published: January 2023

The effect of iron and silicon impurities on the phase composition and properties of the Al–4.3Cu–2.2Yb quasi-binary alloy was determined. In addition to the aluminum solid solution and dispersed eutectic ((Al) + Al8Cu4Yb) containing about 1 % of dissolved iron, Al3 Yb/(Al,Cu)17Yb2 and Al80Yb5Cu6 Si8 phases were identified in the cast alloy microstructure (the latter was not found in an alloy of a similar composition but without impurities). After homogenization annealing at t = 590 °C for 3 h, the structure is represented by compact fragmented and coagulated intermetallic compounds 1–2 μm in size, and a solid solution (Al) with a maximum copper content of 2.1 %. The hardness of deformed sheets significantly decreases after 30 min of annealing, and then changes slightly in the following 5.5 h of annealing at t = 150÷210 °C. After annealing at 180 °C (τ = 3 h), a substructure with a subgrain size of 200–400 nm is formed in the alloy structure. Rolled sheet softening occurs due to recovery and polygonization processes after annealing at temperatures up to 250 °C, and due to recrystallization after annealing at temperature above 300 °C. After annealing at 300 °C (τ = 1 h), the recrystallized grain size is 7 μm. The grain increases to 16 μm after annealing at t = 550 °C (τ = 1 h). The alloy under study has a high level of mechanical properties (conditional yield limit is 205–273 MPa, tensile strength is 215–302 MPa, relative elongation is 2.3–5.6 %) in the annealed state after rolling. Iron and silicon impurities do not lead to the formation of coarse lamellar intermetallic phases and do not reduce the ductility of the investigated alloy.
Features of SHS of multicomponent carbides
Authors: Kochetov N. A. , Kovalev I. D. 
Published: January 2023

Combustion of powders of transition metals of titanium PTS (average particle size 57 μm), zirconium PCRK-1 (12 μm), tantalum Ta PM-3 (8 μm), hafnium GFM-1 (4 μm), niobium NBP-1a (21 μm) with carbon black grade P-803 dispersion 1–2 μm was studied. The combustion process of the compressed samples (mass 2.5–6.9 g, height 1.2–1.7 cm, relative density 0.55–0.61) was performed in an inert argon medium at a pressure of 760 mmHg in the constant pressure chamber. Combinations were studied, Me1 + Me2 + Me3 + Me4 + 4C, Me1 + Me2 + Me3 + Me4 + Me5 + 5C. XRD patterns of the mixtures were recorded on a DRON-3М diffractometer (CuKα-radiation). Combustion product sections were studied using a LEO 1450 VP scanning electron microscope (Carl Zeiss, Germany). The fractional composition and particle size distribution of the mixture were determined according to standard procedure using a Microsizer-201C laser particle size analyzer. Combustion velocity, elongation of samples, phase composition of products were determined. The maximum combustion temperature of the mixture (Ti + Hf + Zr + Nb + Ta) + 5C was measured experimentally for the first time. The morphology and microstructure of the reaction products were also observed. Combustion products of mixtures (Ti + Zr + Nb + Ta) + 4C and (Ti + Zr + Nb + Hf) + 4C contain high entropy carbides, which are solid solutions with the same structural type B1 (space group Fm-3m) and having different cell parameters. Product samples of mixtures (Ti + Zr ++ Hf + Ta) + 4C and (Ti + Hf + Zr + Nb + Ta) + 5C contain high entropy and medium entropy carbides, also representing solid solutions with the same structural type B1 (space group Fm-3m). The results of this work can be used in the production of high-entropy and medium-entropy multicomponent carbides.
ERRO NA APRENDIZAGEM DE QUÍMICA: CONCEPÇÃO DOS PROFESSORES DE QUÍMICA DO ENSINO SECUNDÁRIO GERAL
Authors: Selemane Milagre Alberto , Gomundanhe Almeida Meque , Gueze Geraldo Alfredo 
Published: January 2023

O presente artigo tem como objetivo analisar as concepções que os professores de Química têm sobre o erro na aprendizagem desta disciplina. Para o alcance deste objetivo, optou-se pelo estudo de caso com uma abordagem qualitativa e com suporte bibliográfico. Foi aplicado um questionário como técnica de recolha de dados a cinco professores de Química do Ensino Secundário da cidade de Lichinga. O tratamento e a análise de dados foram baseados na análise de conteúdo. Dos resultados obtidos, constatou-se que os alunos cometem erros procedimentais ligados à sistematização e articulação de códigos e regras da linguagem química. De um modo geral, os professores apresentam uma concepção de erro desvinculada do saber que o aluno detém. Identificado o erro, o protagonismo do professor ou a autonomia do aluno é usada como estratégia para a sua correção. Constatou-se, também, que o erro pode ser utilizado como instrumento de diagnóstico na identificação de lacunas de aprendizagem e como instrumento de planificação e reorientação do processo de ensino e aprendizagem.
Palavras-chave: Erro. Aprendizagem. Química.
Semen parameters in male carriers of Robertsonian translocations (13;14)
Authors: Andreeva M. V. , Kurilo L. F. , Shtaut M. I. , Sedova A. O. , Sorokina T. M. , Chernykh V. B. 
Published: January 2023

Background.Robertsonian translocations (RTs) are the most common type of balanced chromosomal abnormalities. RT male carriers have an increased risk of reproductive disorders, but the causes of this still are not clear enough.Aim.To evaluate semen parameters in RT(13;14) male carriers.Materials and methods.24 men with 45,XY,der(13;14)(q10;q10) karyotype and infertility (n = 23) or recurrent pregnancy loss in spouse (n = 1).Results.Oligoasthenoteratozoospermia was detected in 18 (75 %) patients, asthenoteratozoospermia in 3 (13 %) patients, and azoospermia in 2 (8 %) patients. Normozoospermia was detected in 1 (4 %) patient, whose wife had a history of recurrent pregnancy loss.Conclusion.Infertility in the examined RT male carriers is associated with spermatogenesis disorders, in most cases resulted in oligozooasthenoteratozoospermia.
Resection of the inferior vena cava in patients with kidney tumor and tumor thrombus
Authors: Komarov R. N. , Rapoport L. M. , Ognev O. O. , Ismailbayev A. M. , Tlisov B. M. , Zavaruev A. V. , Antonov A. K. , Shao M. , Korolev D. O. , Ryabov K. Y. 
Published: January 2023

Renal cell carcinoma with inferior vena cava (IVC) thrombosis is a rare disease with a poor prognosis without surgical treatment. The presence of a tumor thrombus in the cavity of the main vessel in most cases is accompanied by massive bleeding during thrombectomy. To reduce the volume of blood loss, it is possible to use cardiopulmonary bypassto reduce the potential risks associated with blood loss and unstable hemodynamics. Sometimes tumor thrombosis can be growth into the vein wall or lead to occlusion IVC, we consider that it’s indication for resection of the IVC. Thrombectomy with laparotomy access can be performed even with type IV tumor thrombosis, if the thrombus is not fixed to the wall of the suprarenal IVC and surgeon have enough view of suprarenal segment.This article presents a variant of surgical treatment of patients with right kidney cancer, type IV IVC thrombosis, occlusion infrarenal IVC and ileofemoral thrombosis. In both cases we made resection IVC – infrarenal segment in first case and suprarenal segment in second case.