High-entropy alloys (HEAs) and compounds, first studied in 2004, represent a new class of materials with promising applications across various technologies and industries. Currently, they include metallic alloys based on disordered solid solutions, ceramic materials based on multicomponent oxides, borides, carbides, silicides, nitrides, and their combinations, as well as ceramic-metal composites. Among the methods for producing high-entropy materials, such as the crystallization of multicomponent melts, mechanical alloying in ball mills, and others, self-propagating high-temperature synthesis (SHS) holds a special place. This review presents the current state of research and development on high-temperature materials produced using the SHS method. It has been shown that the synthesis of metallic high-entropy alloys via SHS is only possible when thermally coupled reactions are employed. This is realized in metallothermic processes and in the synthesis of ceramic-metal composites from elements. The SHS of refractory high-entropy carbides, nitrides, borides, and other compounds can also be performed following the classical element-based synthesis approach. At the same time, the combination of SHS with pre-mechanical alloying of metallic components proves to be effective. For the consolidation of SHS-produced powder products, spark plasma sintering is most commonly used. Additionally, the method of solution combustion synthesis for producing high-entropy ceramics based on oxides is discussed. It has been demonstrated that SHS technology, combined with mechanical activation, mechanical alloying, electric spark plasma sintering, and hot pressing, allows for solving many practical problems in the production of a variety of ceramic, ceramic-metal, and metallic materials based on high-entropy phases.

Natural opoka from the Taskalin deposit in the Republic of Kazakhstan was used as a support for Co–Mn catalysts in the deep oxidation of CO and hydrocarbons. After preliminary preparation of the opoka samples by water washing (opoka I), calcination at 500 °C (opoka II), HCl treatment (opoka III), or combined HCl treatment and calcination at 500 °C (opoka IV), an active phase (AP) consisting of 5 wt. % Co + 5 wt. % Mn (based on metals) was applied via low-temperature combustion of a metal nitrates and urea mixture. The support and catalyst samples were analyzed using XRD and SEM/EDS, and their specific surface area was measured by the BET method. The primary phases identified in the support and catalyst compositions were various modifications of SiO₂, as well as Na-, Ca-, and Mg-aluminosilicates. Due to their low content, AP components in the form of cobalt oxyhydroxide and potassium manganite were detected only on two of the catalyst samples. According to SEM/EDS data, the original nanoscale honeycomb structures on the opoka surface were almost completely destroyed during opoka processing and after AP application. Elemental composition showed notable variability across different granules of both the support and the catalyst, likely due to the natural structural heterogeneity of opoka. It was established that as the complexity of opoka treatment increased, its specific surface area tripled, from 21.0 to 64.1 m²/g. In contrast, the specific surface area of catalysts based on these opoka samples varied irregularly. Testing of the resulting catalysts in the deep oxidation of CO and propane over a temperature range of 150–540 °C revealed substantial activity, with the best performance observed in the catalyst based on water-washed opoka without further treatment. This sample achieved 100 % CO conversion at T = 500 °C and 97 % propane conversion at 540 °C. Thus, natural opoka with minimal processing can serve as an effective support for deep oxidation catalysts for CO and hydrocarbons.

Composite ceramics from aluminum nitride with silicon carbide (AlN–SiC) is promising for applications in both metallurgy and mechanical engineering as a refractory and structural material with enhanced properties, as well as in electronics and photonics as an advanced material for creating various high-performance devices. To fabricate products with optimal properties, compositions (mixtures) of highly dispersed AlN and SiC powders with particle sizes of less than 1 μm must be used. This study is dedicated to improving a simple, energy-efficient method of azide self-propagating high-temperature synthesis (SHS) for such powder compositions, using mixtures of sodium azide (NaN₃) powder and elemental powders of aluminum, silicon, and carbon with the addition of polytetrafluoroethylene (PTFE) powder as an activating and carbidizing additive. During the combustion of these mixtures in a bulk or pressed form in a reactor under 3 MPa of nitrogen gas pressure, the temperature, pressure, and yield of solid combustion products were evaluated. Scanning electron microscopy and X-ray phase analysis were employed to determine the microstructure and phase composition of the combustion products. The addition of PTFE helped to eliminate, in most cases, the drawbacks of the traditional azide SHS approach using halide salts such as (NH₄)₂SiF₆, AlF₃, and NH4_F. While maintaining the high dispersity of the synthesized AlN–SiC powder compositions, their phase composition, particularly in pressed charges, became significantly closer to the targeted theoretical composition, with a substantial increase in SiC phase content and the elimination of undesirable by-products such as silicon nitride and the water-insoluble cryolite salt Na₃AlF₆.

The main properties of the highly dispersed Si₃N₄–TiC composition are presented, demonstrating the potential for using nitride-carbide composite materials across various industries. An in-situ process was employed to synthesize composite ceramics by chemically producing nitride and carbide nanoparticles directly within the composite volume. The study details the development of the technology for synthesizing the highly dispersed Si₃N₄–TiC composition using the azide SHS method during the combustion of mixtures of Ti, C, and sodium azide (NaN₃) powders with polytetrafluoroethylene (PTFE, (C₂F₄)_n) serving as an activating and carbiding additive. Thermodynamic calculations of these reactions showed that the adiabatic temperatures were sufficiently high to sustain a self-propagating combustion mode. Experimental investigations into the microstructure and phase composition of the combustion products are also presented. The synthesized compositions consist of highly dispersed equiaxed particles, which include a mixture of nanosized (less than 100 nm) and submicron (100–500 nm) particles of titanium carbide and nitride, as well as silicon nitride fibers with diame­ters of 50–200 nm and lengths of up to 5 μm. The use of PTFE as a partial replacement for carbon in the mixture during azide SHS eliminated, in most cases, the limitations of traditional approaches for achieving various ratios of target phases of Si₃N₄ and TiC. This enabled the synthesis of highly dispersed Si₃N₄–TiC powder compositions with a phase composition closely aligned with theoretical calculations. Thus, the application of the azide SHS method proved effective for obtaining highly dispersed ceramic powder compositions, including Si₃N₄–TiC and Si₃N₄–TiN–TiC.

The study investigates the structure, porosity, and permeability of highly porous materials based on nickel nanopowders, which were synthesized using ammonium carbonate as a porogen. The process of sample fabrication involves three technological steps: preparation of the initial mixtures of metal nanopowder with a porogen, compaction of the green samples, and subsequent sintering. The average particle size of the nickel powder was less than 100 nm. Ammonium carbonate powders with particle sizes of 40–63, 100–160, 200–250, and 315–400 µm, obtained by sieving, were selected for the experiments. The porogen’s volume fraction in the initial mixtures with nickel nanopowder was 60, 80, 85, and 88 %, with a compaction pressure of 300 MPa. The stages of sintering the nickel nanopowder were preceded by the removal of ammonium carbonate from the green sample by heating it in an argon flow to 100 °C at a rate not exceeding 1 °C/min. The optimal sintering temperature and time for the nickel nanopowder were determined to be 550 °C for 120 min. The research aimed to establish the influence of the porogen’s particle size, its size distribution, and volume fraction on the material’s porosity and permeability. The results showed that increasing the particle size and volume fraction of the porogen leads to higher porosity and permeability of the material. The maximum permeability value achieved was 8.4·10^–12 m² from a sample with 88.5 % porosity, produced using a porogen with a particle size of 315–400 µm. When using porogen powders with two different particle size ranges: 40–50 µm and 315–400 µm (or 100–125 µm and 315–400 µm), the permeability was limited to values obtained from samples using only one of these fractions. In this case, the permeability changed nonlinearly depending on the ratio of each fraction component.

The study focused on titanium-based alloys for medical applications, including commercially available grades VT1-0 and VT6, and a newly developed alloy with the composition (wt. %): Ti–23Nb–5Zr. The surfaces of all samples underwent sandblasting using six different sand fractions, mechanical grinding, polishing by tumbling, tumbling polishing, and, in the case of the Ti–Nb–Zr alloy, electro­lytic plasma polishing. The effects of surface treatment methods and the chemical composition of medical-grade titanium alloys on surface roughness, microhardness, wettability, and interaction with mesenchymal stem cells (MSCs) was investigated. Surface microhardness was measured using the micro-Vickers method with a diamond indenter under varying loads, while surface roughness was determined using a contact profilometer. It was found that electrolytic plasma polishing enhanced both the microhardness and roughness of the alloy compared to tumbling polishing. Wettability was characterized by the contact angle of deionized water, measured using a specialized setup, with the droplet shape described by a 5-point ellipse model. All treated surfaces exhibited wettability; the contact angle increased as surface roughness decreased. However, sandblasting with mixtures containing a wide particle size distribution increased the contact angle due to the more complex surface relief. To evaluate the biological properties of implants made from VT6, VT1-0, and Ti–23Nb–5Zr alloys after the described surface treatments, their effects on cell viability and the adhesive characte­ristics of the materials were studied using a direct contact method with two types of mesenchymal stem cells. The newly developed alloy, which potentially offers superior biomechanical compatibility compared to commercial materials, demonstrated no compromise in surface characteristics or adverse effects on cell viability.

Additive manufacturing technologies, also known as 3D printing, are currently undergoing rapid development and gaining wide popularity, complementing and, in some cases, replacing traditional manufacturing methods. Particular attention is being paid to the fabrication of products from metallic, ceramic, polymeric, and composite materials. Among the seven commonly recognized methods of additive manufacturing, material extrusion stands out, which includes the Fused Deposition Modeling (FDM) technology. The heightened interest in FDM is due to the accessibility of equipment and the wide range of starting materials available, ranging from classic polymers such as PLA and PETG to composite materials, including metal- and ceramic-filled filaments. The objective of this study was to systematize and summarize the existing knowledge on the fabrication process of polymer-ceramic products using ceramic-filled filaments. The paper provides an analysis of the main stages of production, including material selection, filament fabrication, and the 3D printing process. Areas of research and potential applications are also examined.