We investigated composite materials based on electrolytic copper powder containing 1 and 5 wt. % powder of colloidal graphite the addition of trace amounts of copper sulfate and acetate. The materials were obtained through double cold pressing in a mold at a pressure of 600 MPa, intermediate sintering (annealing) in hydrogen at a temperature of 870 °C, and final sintering in vacuum at the copper premelting temperature. To analyze the influence of copper salts on the density, porosity, electrical resistivity, and strength of copper–graphite composite materials, we employed X-ray phase analysis, scanning electron microscopy, conducted strength tests in three-point bending, and determined electrical resistivity. We established that higher graphite content results in increased porosity and electrical resistivity of composite materials, along with decreased strength. In the materials containing copper sulfate, copper is reduced from the salt in the form of nanodispersed particles on the surfaces and inside graphite flakes, leading to a decrease in electrical resistivity compared to copper–graphite composites without salt additives. When copper acetate was added to the composite material, copper is reduced from the salt mainly on the surfaces of graphite particles in the form of microdispersed particles and their aggregations, as the copper acetate solution does not wet the graphite. In this case, the electrical resistivity was somewhat higher than that of the composite with sulfate but lower than that of the material without salts. The bending strength of the studied materials decreased as salts were introduced due to increased porosity and emerging defects in the crystal structure of graphite during its intercalation with copper.

The paper presents the results of theoretical and experimental studies regarding the quality of diffusion welding of the beryllium–copper composite. Numerical investigations of the parameters of heterodiffusion of diffusants and the thickness of the Be–Cu pair welded joint under varying temperature-time conditions were conducted. The analytical examinations revealed that the thickness of the diffusion weld at the Be–Cu joint varies between 26 and 345 µm, with the temperature increasing from 800 to 1000 °C and the holding time ranging from 20 to 120 min. The calculated layer thickness during the diffusion welding of a Be–Cu pair at 800 °C for 2 h is 65 µm, with 15 µm on the beryllium side and 50 µm on the copper side. Notably, a CuBe₃ intermetallic compound zone can form in the diffusion weld, which should be considered an adverse factor that reduces the mechanical properties. To theoretically substantiate the modification of the structure and properties of the diffusion zone, a numerical study of welding was carried out using a 10 μm thick nickel foil spacer, which is readily soluble in beryllium. It was demonstrated that after exposure to temperature-time conditions at 900 °C for 20 min, a 50 µm wide diffusion-bonded joint is formed. Its structure includes two single-phase zones of solid solutions based on copper and beryllium, as well as two two-phase regions consisting of solid solutions hardened with intermetallic compounds. Since the weld lacks structural zones consisting solely of intermetallic compounds (unlike when welding the Be–Cu diffusion pair), there are grounds to anticipate a reduction in the embrittling effect on the weld.  The results obtained from the analytical studies can serve as the foundation for a theoretical prediction method for assessing the quality of diffusion welding of the beryllium–copper composite.

Composite ceramic materials based on B₄C with the addition of TiB₂ in amounts of 0, 10, 20, 25 and 30 mol. % have been studied. Titanium diboride was synthesized from TiO₂ powder and nanofibrous carbon using the boron carbide method in an induction furnace at 1650 °C in an argon atmosphere. The samples were produced by hot pressing at 2100 °C and 25 MPa in an argon environment. The phase composition was determined, and the apparent density and open porosity of the experimental materials were measured. The microstructure was assessed using optical and scanning electron microscopy. The investigations revealed that an increase in the TiB₂ content reduces the open porosity while concurrently enhancing the relative density of the boron carbide ceramics. For a sample containing 30 mol. % TiB₂, the open porosity and relative theoretical density were 1.6 and 99 %, respectively. Using XRD and XRS analyses established that the synthesized materials are comprised of two phases: B₄C and TiB₂. The average grain size of TiB₂ was 0.85 ± 0.02 µm for the sample with 10 mol. % TiB₂ and 8.90 ± 0.25 µm for the material with 30 mol. % TiB₂. It was found that at higher TiB₂ concentrations, large clusters of grains are formed. The destruction pattern of B₄C grains is intragranular, while TiB₂ grains are characterized by intergranular destruction. For a sample containing 30 mol. % TiB₂, the fracture toughness was 4.97 ± 0.23 MPa∙m^0.5, and the hardness was 3320 ± 120 HV_0.5. Therefore, the addition of TiB₂ at these specified concentrations facilitated a 30 % enhancement in fracture toughness relative to single-phase B₄C while preserving a high level of hardness.

Mining wastewater, characterized by elevated salt levels, necessitates effective treatment to prevent contamination of underground and surface water. Traditional methods for treating large volumes of mining wastewater with high total dissolved solids are expensive, and cost-effective alternatives are limited. In this study, we propose a solution to this challenge: the sorption of dissolved substances using a carbonaceous sorbent derived from waste, specifically rice husk biochar. To enhance the sorbent’s efficiency, we subjected it to electromagnetic activation, resulting in increased carbon content (from 43.3 to 78.5 % compared to the initial biochar), reduced impurities, and particle size reduction to the nanoscale (1–50 nm) with the formation of mesopores (mean diameter from the adsorption isotherm is 167 Å) and micropores (4.92 Å). This process contributes to improved compositional homogeneity. The effectiveness of the proposed sorbent was validated through the treatment of wastewater from Kirov Mine (Novoshakhtinsk, Rostov Region) under laboratory conditions. The removal rates for dissolved heavy metal ions (iron, zinc, manganese) were found to be 89, 84 and 26 %, respectively. A recommended two-stage sorption treatment involves: (1) static sorption using electromagnetically treated rice husk biochar at a concentration of 0.5 g/dm³; (2) subsequent reagent treatment of the suspension (SKiF-180 reagent, 1.0 mg/dm³), addition of potassium permanganate for manganese removal, settling for 30 min, and non-pressure filtration with a rice husk biochar filter.

In this study, we studied the effects of aluminum coating treatment temperature on the microstructure and phase composition when applied to a VT6 titanium alloy substrate within a low-pressure arc discharge plasma environment. The ion-plasma treatment was conducted at 450 and 500 °C, employing argon shielding, while the aluminum coating was deposited using the vacuum-arc process, resulting in a coating thickness of ~3 μm. Microstructural analysis was performed using a scanning electron microscope, and the structural and phase composition were examined using X-ray diffraction (XRD) imaging in symmetric imaging mode with CuK_α radiation. Our findings demonstrate that the application of the aluminum coating initiates the formation of a near-surface α-stabilized layer, extending up to 2.5 μm in thickness due to the heat generated during the ion cleaning process. Subsequent ion-plasma treatment further results in the development of a TiAl₃ intermetallide site, reaching thicknesses of up to 1.5 μm, while the α-stabilized region expands to 5.5 μm. Higher temperatures during the treatment process contribute to an increase in the thickness of these aforementioned layers and also lead to the emergence of an intermediate TiAl intermetallic layer.

This article presents the results of an experimental study on the physical and mechanical properties of the surface layer of the VAL10 aluminum alloy after pulsed laser treatment, conducted in a bath with an aqueous solution of polysilicates (PS) at various concentrations. Ceramic coatings were produced on specimens measuring 10×10×3 mm. The laser processing of aluminum alloy specimens was carried out using an Nd:YAG laser. The study demonstrates that the quality of the resulting surface and its properties can vary depending on the laser exposure parameters, the concentration of the polysilicate solution, and the overall processing technique. The scattering of radiation by the PS solution layer leads to a significant reduction in surface roughness. In specimens processed in ambient air, the crater sizes on the surface exceeded 400 μm, while for specimens processed in a PS solution, they did not exceed 100 μm. A comparative analysis of the impact of solution concentration on elemental composition was performed. The study also included an investigation of friction characteristics and the measurement of microhardness of the modified surface. The research revealed that surface hardening processes occur as a result of the treatment, associated with the filling of recesses with high-strength oxides. This enabled the creation of a mixture containing silicon carbide and aluminum oxide in the surface layer of the specimens. Furthermore, wear tests of the modified surface were conducted using a “ball–specimen” tribological coupling. Specimens subjected to laser irradiation in a PS solution demonstrated increased wear resistance (a 40 % reduction in wear) and a 30 % decrease in the friction coefficient. Additionally, an increase in microhardness was observed.

The presented paper experimentally demonstrates the potential expansion of stereolithographic prototype utilization. Two methods for manufacturing plastic prototypes are proposed, enabling the subsequent substitution of the polymer material with either metal or ceramics. The first method involves additional actions by the prototype designer during the modeling stage. The second method necessitates alterations in the technological processes of model preparation and prototype manufacturing using a stereolithography apparatus. Material substitution occurs in two stages. Initially, cavities in the prototype are filled with powder material or a mixture of powder and water. Although titanium powder was chosen as the test material, the proposed technology permits the utilization of a broad spectrum of powder materials, encompassing both metallic and ceramic options. The subsequent stage involves heat treatment, where the polymer is eliminated, and the metal powder is sintered while retaining the original shape and dimensions of the prototype. Heat treatment of the acquired prototypes was conducted in both argon and atmospheric air environments. The utilization of different gas media might induce chemical transformations in the material filling the prototype. The experiments lead to the conclusion that the proposed approaches show promise and merit further development. Additionally, we contemplate amalgamating the two methods in the future to attain an optimized final outcome. The data we have gathered could significantly contribute to broadening the scope of stereolithography applications, given that this technology presently represents one of the most precise, widespread, and accessible additive manufacturing methods.