International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Galvanized steel pipes have long been widely used in drinking water supply systems due to the zinc coating that protects the steel from corrosion. However, during operation, especially when hot water is supplied, the zinc protective layer gradually breaks down, especially if there are galvanic pores in the pipeline or stray electric currents are generated in the pipeline. If the zinc coating is damaged, the steel base begins to corrode, rust forms, the pipe wall thickness decreases and the water quality deteriorate.
In addition to internal corrosion, a significant problem is external pipe corrosion caused by condensation forming on the surface of cold-water pipes. When the pipe surface temperature is below the dew point of the ambient air, moisture accumulates on it. Long-term wetting of the surface, especially if the zinc coating or protective paint layer is damaged, creates favorable conditions for the development of atmospheric corrosion. The corrosion process is further accelerated by poor indoor ventilation, high relative humidity or incorrectly calculated insulation layer thickness.
The article will examine two corrosion situations of steel pipes for drinking water supply using metallographic, water parameter studies, and stray current measurements.

Titanium matrix composites reinforced with titanium borides (TiB) represent a promising class of advanced structural materials due to their high specific strength, hardness, wear resistance, and thermal stability. The combination of titanium alloys with ceramic TiB reinforcing phases enables the development of lightweight materials with improved mechanical and эксплуатаційними characteristics for aerospace, biomedical, and engineering applications.
This study investigates the fabrication of Ti/TiB titanium matrix composites using X-Beam 3D printing technology. The process is based on electron-beam additive manufacturing under vacuum conditions, which ensures stable melting conditions, reduced oxidation, and controlled heat input during layer-by-layer deposition. Special attention was focused on the in situ formation of TiB reinforcing phases and their influence on the microstructure evolution of the composite material.
Microstructural analysis was carried out using scanning electron microscopy and metallographic techniques. The obtained results demonstrated the formation of dense composite structures with relatively low porosity and homogeneous distribution of reinforcing phases within the titanium matrix. TiB particles and whisker-like precipitates were observed to form during solidification, contributing to microstructure refinement and strengthening effects.
The fabricated Ti/TiB composites exhibited improved structural uniformity and enhanced hardness compared with unreinforced titanium materials. The morphology and distribution of TiB phases were found to depend on the thermal conditions and processing parameters of X-Beam printing. The results confirm the potential of X-Beam additive manufacturing for producing advanced titanium matrix composites with tailored microstructure and improved performance characteristics.

The industrial processing of peppers and eggplants yields substantial quantities of byproduct materials, including peels, seeds, and stems. These secondary raw materials are concentrated sources of bioactive compounds, notably phenolic acids and flavonoids, which possess significant potential for repurposing due to their inherent biological activities. This study aimed to quantify the phenolic acid profiles of aqueous-alcoholic extracts derived from red sweet pepper, red hot pepper, and eggplant waste, and to evaluate their inhibitory efficacy specifically against saprophytic microorganisms responsible for food spoilage. Extracts were prepared using varying concentrations of ethanol (20%, 40%, and 70%). High-Performance Liquid Chromatography (HPLC) was employed for the identification of phenolic acids. The antimicrobial potential was assessed using the agar well diffusion method, while the Minimum Inhibitory Concentration (MIC) was established via serial dilutions. The extracts demonstrated robust antifungal and anti-yeast activity against key spoilage organisms, including Saccharomyces cerevisiae, Candida utilis, Aspergillus niger, Penicillium chrysogenum, and Fusarium moniliforme. Inhibition zones ranged from 9 mm to 20 mm, with MIC values spanning 60 ppm to 600 ppm. A direct correlation was observed between the concentration of specific bioactive phenolics and the degree of microbial suppression. Given their high phenolic content and proven effectiveness in inhibiting common spoilage fungi and yeasts, these materials—and the flours derived from them—offer a viable, bioactive alternative for extending shelf life in food industry applications.

Pepper and eggplant processing generates significant amounts of waste raw materials, such as peels, seeds, stems and residual pulp. These waste products are rich in bioactive components, such as phenolic acids, flavonoids, anthocyanins, capsaicinoids and glycoalkaloids, which determine their antimicrobial and antioxidant activities. Therefore, waste raw materials from peppers and eggplants represent a potential for industrial application. The aim of the present study was to determine the phenolic acid content in aqueous-alcoholic extracts of red sweet peppers, red hot peppers and eggplants as well as their antimicrobial activity against pathogenic microorganisms, causing food-borne toxicoinfections and toxicoses. Aqueous-alcoholic (20%, 40%, 70%) extracts of waste raw materials of red sweet peppers, red hot peppers and eggplants were used in the present study. Phenolic acids were determined by HPLC, and the antimicrobial activity – by agar diffusion method with wells. The minimum inhibitory concentration (MIC) was determined by the serial dilution method. The aqueous-alcoholic extracts from waste raw materials of red sweet peppers, red hot peppers and eggplants exhibited bactericidal activity against the pathogenic bacteria Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25293, Salmonella enteritidis ATCC 13076, Salmonella abony NTCC 6017, Listeria monocytogenes ATCC 19111, Pseudomonas aeruginosa NBIMCC 1390, Enterococcus faecalis ATCC 19433, with inhibition zones of 9 mm to 20 mm and MIC ranging from 60 ppm to 600 ppm. The relationship between the antimicrobial activity of the aqueous-alcoholic extracts and the presence of bioactive components with an inhibitory effect in them has been revealed. Their water-alcoholic extracts are rich in phenolic acids, which also determine their antimicrobial activity against pathogenic and saprophytic microorganisms. The flours obtained from them are carriers of bioactive components and have antimicrobial action. This makes them suitable for use in the food industry

This work is devoted to the development and research of a new technology for processing bar scrap from 40X steel to obtain high-quality finished metal products in the form of a screw reinforcement profile. The developed technology included two stages. At the first stage, the round-section bar scrap is formed on a radial-shear rolling mill to obtain conventional bars of the desired diameter and create initial conditions for the formation of an ultrafine grained gradient structure in the resulting screw profile. The second stage is the direct production of a screw profile with a gradient ultrafine-grained structure on a combined installation. Metallographic studies have shown that after the implementation of the second stage of obtaining a screw reinforcement profile, a gradient structure is observed in 40X steel, with equiaxed grains, the size of which lies within 1.2-1.4 μm in the peripheral region and to a greater extent with elongated, directional-oriented grains in the central region of the resulting reinforcement.

The work is dedicated to the study of the properties of detonation coatings AlB12-30 wt.% Al (AB70) applied to Steel 45 using the DNEPR-5M installation. The coatings have the following characteristics: thickness h ~ 170-200 μm, Hμ = 27-29 GPa, HV = 4.35 GPa. Changes in the tribological characteristics of the composite depending on the friction mode are analyzed. The AB70 coating is found to have stable tribological characteristics: f = 0.21-0.38, wear rate I = 3.3-8.6 μm/km. Samples with coatings exceed uncoated Steel 45 in wear resistance. Changes in the surface structure after friction depending on the sliding speed and load are shown. Two wear mechanisms – oxidative and adhesive-abrasive – are established. A conclusion was drawn regarding the possibility of using the AlB12-Al system to apply detonation coatings.

This study investigates the mechanisms of liquid-phase assisted sintering in high-entropy ceramics (HECs) using a nickel binder. The research focuses on the densification process of (Ti, Zr, Hf, Nb, Ta)C-based cermets with 10 vol% Ni, and how pressure influence liquid-phase extraction. Results show that eutectic reactions between Ni and carbide phases was observed during liquid formation below 1400°C. Microstructural analysis reveals a nickel-rich matrix, solid solutions, and NbC-based carbide inclusions in the extracted drop. These findings provide insights into optimizing processing parameters for advanced HEC-based composites.

The work aimed to evaluate the effect of microalloying titanium in proportions of 1 to 5 wt.% on the microstructure and microhardness of a precipitation-hardenable martensitic stainless steel. The standard chemical composition of martensitic steel 17-4PH was used, to which 1; 2; 3; 4 and 5 wt.% Ti was added, respectively. Microstructural analyses revealed changes in the crystal grains and precipitation effects from the solid solution of the alloy. Microhardness measurements were also performed, which demonstrated that withincreasing Ti content in the alloy the metallic matrix becomes harder. The study confirms that microalloying with Ti is beneficial for the development of martensitic stainless steels to increase mechanical properties, even without the application of subsequent heat treatments.
The results obtained in this work represent a starting point for the development of new customized alloy recipes, adapted to specific applications, where a high value of hardness, as well as microstructural stability or wear resistance are required.

The contact interaction between the metal matrix composite based on Ti64 and the B4C-based composite was investigated. It is shown that the interaction process is influenced by the annealing temperature and holding time. The phase that formed independently of the contact pair is TiB. However, the thickness of the products formed at the boundary depends on the contact pair. In case of the Ti64-B4C pair the thickness is 70 μm, while for (Ti64-40 wt% TiC)-B4C it becomes 10 μm. This significant difference in the thickness is due to the presence of refractory particles (TiC) in (Ti64-40 wt% TiC)-B4C couple, because the TiC phse reduce the diffusion of Ti into the contact zone.

Titanium–titanium boride (Ti/TiC) metal matrix composites have been widely identified as promising materials for various applications. The traditional ingot metallurgy processing strategies used to fabricate these materials are energy intensive and have fallen short of their perceived mass production potentials. Powder metallurgy processing of Ti/TiC composites from titanium and TiC powder blends, is currently widely used for the cost-efficient production of such composites. Additional processing by the method of hot pressing improves the structure and mechanical properties of this class of materials. The composites have the heterogenous microstructure with areas high hardness area over 1173 HV. While matrix and inclusions had the value of 700 HV.

The article presents the results of research aimed at assessing the quality of forgings depending on the forging parameters used. The forging and subsequent heat treatment processes revealed the occurrence of cracks in the forgings. The article examines the possible causes of cracks, which can be caused by carburizing annealing and loss of plasticity during stress relaxation. Tool wear and damage during forging also affect the formation of cracks. These factors were identified as key factors contributing to the formation of non-metallic oxide inclusions, the transfer of surface defects and the formation of lamellar propagation during subsequent heat treatment. The findings highlight the influence of tool conditions and process parameters on the quality and reliability of steel forgings..

This work is devoted to the study of a new technology for processing bar scrap – a precision shaft made of Cf53 structural steel (DIN 17212) that has proven its service life and produces high-quality finished metal products in the form of a screw reinforcement profile. The precision shaft used for recycling of its proven service life included two stages: preliminary deformation of the shaft on a radial shear rolling mill to obtain rods of the required diameter and create initial conditions for the formation of a gradient ultrafine-grained structure in the resulting screw profile; direct production of a screw profile with a gradient ultrafine-grained structure on a combined installation. The conducted research has shown that the new combined technological process of rolling bar scrap is feasible in practice and makes it possible to obtain a high-quality finished product from this scrap in the form of a screw reinforcement profile with a gradient ultrafine-grained structure.