Том 29, № 3 (2025)
Mechanical Engineering
Effects of original microgeometry on the surface quality of AMg6 aluminum alloy parts following ultrasonic surface plastic straining
Аннотация
We study the effect of original surface microgeometry and the number of indenter passes on the microhardness and roughness of the surface layer of products treated by ultrasonic surface plastic straining. The study was conducted using cylindrical specimens made of AMg6 aluminum alloy. Ultrasonic surface plastic straining was performed according to a tangential input of ultrasonic vibrations for the number of indenter passes varying from 1 to 5. The original roughness of aluminum specimens ranged from Ra 0.44 to Ra 3 µm. The quality of the surface treated by ultrasonic surface plastic straining was assessed based on roughness and microhardness parameters. For the selected range of original surface roughness, the roughness and microhardness of the specimens reached stable values after 1-2 intender passes. The efficiency of ultrasonic surface plastic straining for products made of AMg6 aluminum alloy is largely determined by the microgeometric and physicomechanical characteristics of the original surface, as well as by the number of processing cycles. Thus, a significant decrease in roughness and increase in microhardness were observed in the formed specific cellular microgeometry of the surface. Increasing the number of passes above 1-2 appears ineffective in terms of further improving the quality of the surface layer. The obtained results can be used to optimize technological processes in mechanical engineering, aviation, automobile, and other industries, optimize the selection of finishing operations, ensure contemporary quality requirements for the processed surface of aluminum alloy products, and increase the economic efficiency of production.
iPolytech journal. 2025;29(3):308-321
308-321
Experimental study of different methods for post-processing plastic parts manufactured by 3D printing
Аннотация
The article aims to compare and evaluate methods for surface treatment of plastic products manufactured using 3D printing technology, namely by fused deposition modelling (layer-by-layer FDM). The experimental studies were conducted on ABS plastic samples using various tools for physical, thermal, and chemical processing. These included an electric engraver with coarse and fine grain grinding wheels, a felt polishing wheel and abrasive paste, burrs; acetone, dichloromethane (methylene chloride); a heat gun; a NEJE Master semiconductor laser engraver with adjustable laser power. The study was conducted utilizing portable optical and digital microscopes. The article focuses on the existing methods for surface treatment of ABS plastic products and highlights their advantages and disadvantages. In order to compare the methods of surface treatment of ABS plastic products, a visual assessment of the results of surface treatment by various methods was carried out according to several criteria. We compared the obtained types of surfaces, printer resolution (i. e., layer thickness and X-Y resolution), surface uniformity, degree of deformation, presence of scratches/cracks, cavities, buildups, and blisters employing the proposed criteria. The comparative analysis of various processing methods demonstrated that the best result in terms of quality was achieved with surface treatment using laser radiation. However, this method was shown to have a drawback which is the need for preliminary laser adjustment and the potential complexity of processing three-dimensional parts. The results of the present study can be applied in mechanical engineering when manufacturing parts using additive technologies to manage the surface quality of plastic products.
iPolytech journal. 2025;29(3):322-335
322-335
Improving the reliability of a ceramic plain bearing
Аннотация
In this study, we search for a design solution to ensure a reliable and long-term operation of a friction unit with a ceramic plain bearing. To that end, the stress-strain state of the ceramic insert is optimized with respect to actual loading conditions. The bearing unit is designed accounting for the properties of ceramic materials, which show low strength reliability under the action of tensile stresses. To improve the solution accuracy, we determine the actual contact area, taking into account the load unevenness in the bearing. In addition, since the insert surface is assumed to be complexly stressed, the calculation is based on equivalent stresses. The criterion is to minimize equivalent stresses, which corresponds to the optimal tension justifying the bearing application. The analysis involves the discrete-continuous option of the finite element method with the variational principle according to the Lagrange method. The calculation software provides for the values of equivalent stresses depending on tension and selects its optimal value. As a result of the performed analysis, the geometric shape of the ceramic insert is optimized. In the proposed design, the brittleness inherent in ceramic materials can almost be compensated by minimizing tensile stresses. Thus, the reliability and durability of the plain bearing increase. An original design of a plain bearing with a ceramic insert is proposed. This design allows advanced ceramic structural materials to be used in plain bearings, which extends the operational range of friction units. In order to overcome the fragility of ceramic materials, special design techniques should be developed to withstand tensile stresses through optimally selected tensions creating compressive stresses in the insert. Optimal tension parameters can be selected using numerical methods of stress-strain state analysis, in particular, the finite element method.
iPolytech journal. 2025;29(3):336-344
336-344
Study of solid carbide end mills for machining workpieces with hardness gradient
Аннотация
The present paper sets out to investigate the service life of solid carbide end mills for machining workpieces with an HRC 40 base hardness and a surface layer hardness of HRC 65 and greater. For machining, solid carbide end mills with four and nine teeth were used; control mills were uncoated. The studied mills were coated with 5 µm thick multilayer nanostructured coatings applied using the condensation method with ion bombardment in a Bulat unit. Three types of coatings were studied, including titanium carbonitride with titanium nitride layer (TiCN+TiN); a mixture of titanium and aluminum with aluminum oxide, mixed titanium and aluminum nitride, and aluminum oxide layers (TiAl+Al2O3+(TiAl)N+Al2O3); titanium carbonitride with mixed titanium and aluminum nitride, aluminum oxide, and titanium carbide layers (TiCN+(TiAl)N+Al2O3+TiC). The surface layer hardness of workpieces exceeded HRC 61. The surfacing was applied using a TST 350 arc welding machine equipped with a PDG0–527-4A semiautomatic welding device with a PP-AN167 flux-cored wire. The service life of a nine-tooth mill, both coated and uncoated, was found to exceed that of a four-tooth mill. Experimental results show that TiCN+(TiAl)N+Al2O3+TiC coating is more appropriate for a nine-tooth mill. This coating surpasses the (TiAl)N+Al2O3+(TiAl)N+Al2O3 coating for the resistance period in the entire range of milling speeds. The dependencies of the tool life on the milling speed were separately obtained for solid carbide nine- and four-tooth end mills with various multilayer nanostructured coatings. The identified dependencies can be used to establish the most appropriate operating conditions for these mills. The research results can be used to develop technologies for manufacturing parts with a surface layer hardness above HRC 65.
iPolytech journal. 2025;29(3):345-352
345-352
Power Engineering
Method for normalizing initial data of wind measurements in complex terrain areas
Аннотация
We set out to develop a method for normalizing the initial data of wind measurements obtained from meteorological stations for the terrain conditions of the wind turbine or power plant location. To solve the problem, we propose a numerical solution of a system of differential equations for the conditions of a turbulent environment in the lower surface layer of atmosphere at a height of 1000 m and less from the earth surface. The analogous object is a 300 kW Kamai wind turbine installed in Ust-Kamchatsk, Russian Federation. We use a simplified system of equations, which accounts for the terrain to determine the wind velocity at the wind power plant site. Satellite maps and well-known tables of reduced landscape roughness are used to determine the terrain. The feasibility of this method, as well as the effect of initial data accuracy on the forecast output of the wind power plant are assessed using the example of wind resources in Ossora, Kamchatka Peninsula, Russian Federation. The proposed approach reduces the error of the subsequent forecast for the wind power plant output to 15%. Moreover, the proposed method requires no long-term observations of daily and annual changes in wind velocity, which is of particular importance for newly built wind power plants. The meteorological network provides data relevant for the region and describes its characteristics as a whole, thus complicating the determination of the resource at a specific point of the region with a time interval of up to 3 h. The proposed solution concerns both the design and operation of a wind power plant by allowing the site distribution of wind velocity to be obtained even when data for a larger region are used.
iPolytech journal. 2025;29(3):353-362
353-362
Analysis of the effectiveness of relative methods for power cable fault detection
Аннотация
The aim is to evaluate the effectiveness of relative methods used to locate faults of 6–10 kV power cables operated at an industrial enterprise. To achieve this goal, the reflectograms obtained on damaged power lines were compared with the reference ones. The research object is represented by three 6–10 kV power cables with paper-oil insulation, 900–3000 m long, and with a service life of more than 30 years. The type of damage to all power lines was a single-phase creeping discharge. The study employed various methods (TDR, ARC, ICE/Decay) to locate faults in the lines and the test rigs. The equipment used to detect cable fault locations included a REIS-305 reflectometer, a GVI 24.3000IDM high-voltage pulse generator, and a SDC50 current sensor. Multiple soundings of the power lines under study were performed to obtain reflectograms containing information about the distance to the fault location. As a result of the conducted research, varying in informativeness reflectograms of power cables were taken. We managed to select the true ones from them. Serious discrepancies in the shape of the displayed sounding pulse in the reflectograms were identified in comparison with the reference ones given in relevant technical literature. The article highlights issues concerning the application of the ARC method. The challenges consist in the breakdown voltage limitation at the cable faults. Each cable fault is shown to have its own characteristics. However, their causes are difficult to identify since it is impossible to establish the process of and the prerequisites for electric current passage when a short circuit arises. Drawing on the results of the undertaken study, a recommended algorithm was developed to determine the distance to the location of a power cable fault. However, due to the small amount of scientific research on this subject matter, no absolutely universal approach to this problem exists at present; its creation requires further investigation.
iPolytech journal. 2025;29(3):363-375
363-375
Metallurgy
Lithium sorption from natural brine
Аннотация
The study aims to investigate the efficiency of lithium extraction from highly mineralized calcium chlo ride brine of the Siberian Craton using a synthesized sorbent based on layered aluminum-lithium hydroxide. The re search into the sorbent properties (swelling characteristics, mechanical strength) was conducted in accordance with GOST 51641-2000 using an ELMI S-3L.A20 orbital shaker and a high-precision analytical balance CAS CAUW-220D. The sorption kinetics was studied under static conditions. The total dynamic capacitance and dynamic exchange ca pacity (before “breakthrough”) at brine flow rates from 1 to 3 column volumes per hour were determined in dynamic experiments. 100 continuous sorption-desorption cycles were carried out. The analysis of solutions for the element content was performed by the ICP-AES method with an iCAP 7400 Radial inductively coupled plasma atomic emis sion spectrometer. According to the conducted research, the swelling capacity of the sorbent was 19%, grindability equaled 1.72%, and abrasion amounted to 0.27%. The time to reach semi-equilibrium during lithium sorption under static conditions was 3 minutes. The total static capacitance equaled 5.5 mg/g; the total dynamic exchange capacity amounted to 5.5–5.7 mg/g. At a brine flow rate of 2 column volumes per hour, 95% lithium extraction was achieved. For commercial lithium recovery at a level of 95% at a flow rate of 1–2 column volumes per hour, 2 columns are re quired (or 3 columns at a flow rate of 3 column volumes per hour). It is shown that the sorbent capacity is maintained at a level of 5.6 mg/g throughout 100 sorption-desorption cycles. The concentration ratio (Ca2++Mg2+)/Li⁺ in the eluate is reduced 682-fold compared to the original brine. Thus, the sorbent demonstrates high efficiency for lithium extraction from brines with extremely high calcium ion content. The high values of the rate of reaching semi-equilib rium, capacity, mechanical strength, as well as operational stability over 100 sorption-desorption cycles confirm the industrial potential of sorption extraction of lithium from highly mineralized calcium chloride brines.
iPolytech journal. 2025;29(3):376-388
376-388
Improved gold diagnostic leaching procedure for carbonaceous preg-robbing ores
Аннотация
The article presents an improved procedure for the diagnostic leaching of gold in carbonaceous preg-robbing mineral ores. When researching highly preg-robbing ores, classic diagnostic gold leaching approaches often lead to distorted results: the proportion of cyanidable gold is underestimated, while recoverable gold is er roneously attributed to refractory forms. This discrepancy arises from the high natural sorption activity of organic carbon, which interferes with artificial sorbents at all leaching stages to competitively adsorb gold from the liquid phase of cyanide pulp. An advanced diagnostic two-stage leaching procedure for highly preg-robbing materials has been developed: first, cyanidation is carried out under standard conditions with an increased sorbent load, then high-temperature sorption processing at a temperature of 80–95°C for 2 hours is carried out with fresh sorbent. Tests carried out on various carbonaceous mineral products demonstrated improved gold recovery efficiency during cyanidation. The 4.2–12.5 % increase in obtained cyanidable gold as compared to the conventional method enables more precise differentiation of gold forms and optimization of processing strategies for preg-robbing ores. This pro cedure is particularly valuable for ores having a high organic carbon content and strong preg-robbing capacity due to providing more reliable phase characterization of gold and supporting accurate selection of processing technolo gies. The protocol is recommended for implementation in both laboratory and industrial practice.
iPolytech journal. 2025;29(3):389-398
389-398
Software development for balance calculations of ilmenite concentrate processing
Аннотация
The aim is to develop dedicated software for automating the calculation of material flow balances in the process flow diagram of ilmenite concentrate processing in order to optimize titanium production, reduce raw material losses, and enhance the efficiency of process management. Material flow analysis is used to comprehensively monitor materials flow at all stages of titanium-containing raw material processing. The stages include reduction smelting, slag chlorination in the melt, titanium tetrachloride extraction and purification, magnesiothermic metal reduction, and vacuum separation. The software package developed in Python consists of four modules. Each module calculates the material balance for a specific technological process stage. Interaction with the user is implemented through MS Excel for the convenience of data entry and visualization of results. The software package ensured the calculation of com plete material balances with a deviation of less than 0.2%. The analysis revealed technology-related titanium losses at the level of 21.4% compared to the initial amount of metal in the concentrate. It was shown that the most substantial Tilosses occurred at the stages of reduction smelting (6.63%, mainly into dust and cast iron) and titanium tetrachloride (IV) purification (12.92%, into by-products). Smaller losses were recorded during slag chlorination (0.33%), titanium tetrachloride (IV) reduction (2.50%), and reaction mass separation (0.51%). The designed programs were published in the official Rospatent Bulletin Computer Programs. Databases. Topology of Integrated Circuits. The developed software package enables the automation of material balance calculations in titanium production from ilmenite concentrate. The key areas for improving the technological process include modernizing the reduction smelting and titanium tetra chloride purification stages where maximum losses of the target metal are observed.
iPolytech journal. 2025;29(3):399-411
399-411
Effect of the anode paste composition of a self-baking anode on the performance of electrolytic aluminum production
Аннотация
The present study aims to analyze the effect of the coke type (petroleum, pitch) in the composition of an anode paste for a self-baking anode on electrolysis indicators. We collected production data from operating S-8B(M) electrolytic cells with Soderberg anodes in the period from June to October 2024, including 172 and 186 electrolytic cells installed in Series 1 in Series 2, respectively. The yield of coal foam is higher in electrolytic cells with petroleum coke anodes: 15.9 kg per 1 electrolytic cell versus 8.4 kg in cells with anodes based on pitch coke paste. During the studied period, the specific power consumption for a series of cells operating with petroleum coke paste was 15,393 kWh/t Al versus 15,341 kWh/t Al. The consumption of petroleum coke anode paste per 1 electrolytic cell is 1.82 t higher than that of cells operating on pitch coke at an anode combustion rate of 1.5 and 1.47 cm/day, respectively. The anode pin rearrangement performed during the research period revealed 285 technological viola tions, e.g., pitch leaks and gassing, for petroleum coke anodes as compared to 121 violations for another coke type. A comparative analysis of the data collected during the maintenance of electrolytic cells with Soderberg anodes proved pitch coke anodes to have the lowest carbon foam yield, specific power and anode paste consumption, and anode combustion rate. Thus, using pitch coke in the anode paste for self-baking anodes of electrolytic cells can enhance the efficiency of aluminum production.
iPolytech journal. 2025;29(3):412-424
412-424