This study presents the results of spark plasma sintering of powders within the boron–carbon–chromium system, focusing on boron carbide (B₄C), chromium carbide (Cr₃C₂), and chromium diboride (CrB₂). The powders were synthesized using the original vacuum-free direct current arc reactor, where the starting powder mixture was exposed to an arc discharge for 60 s under a direct current of 200 A. Bulk samples based on B₄C and CrB₂ were sintered under identical conditions, with a temperature of 1800 °C and a pressure of 60 MPa, while the sintering of Cr₃C₂-based ceramics was conducted at 1300 °C and 30 MPa. In some cases, sintering additives – 25 wt. % Cr₃C₂ and 20 wt. % CrB₂ – were introduced during the sintering of B₄C-based bulk samples. The phase composition of the sintered samples was analyzed using X-ray diffraction (XRD), while the microstructure and elemental composition were examined via scanning electron microscopy (SEM). The hardness of the sintered ceramics was measured using a Vickers indenter under a load of 1 kg, revealing hardness values of 22.7 ± 1.8 GPa for B₄C, 12.6 ± 0.3 GPa for CrB₂, and 11.4 ± 0.1 GPa for Cr₃C₂. The introduction of 25 wt. % Cr₃C₂ as a sintering additive in B₄C-based ceramics reduced the hardness to 17.7 ± 5.6 GPa; however, it significantly improved the fracture toughness, increasing it from 2.5 ± 0.2 to 3.3 ± 0.3 MPa·m^1/2. Conversely, the addition of 20 wt. % CrB₂ during B₄C sintering led to an increase in the bulk sample’s hardness from 22.7 ± 1.8 GPa to 26.8 ± 1.3 GPa.

Stainless steel powders are among the most widely used raw materials for the production of small, high-precision engineering components by metal injection molding (MIM), a process that combines metal powders with molten polymer binders. This study focuses on the development of feedstock composition and processing parameters for MIM production using domestically sourced components: a martensitic stainless steel powder grade 09Cr16Ni4Nb, a polyoxymethylene-based binder, and processing additives including stearic acid, beeswax, and low-density polyethylene. The starting stainless steel powder had a spherical morphology with a predominant particle size range of 8–23 μm. Scanning electron microscopy, melt flow index (MFI) testing, and helium pycnometry were employed to investigate the microstructure, rheological behavior, and physical properties of the resulting feedstock granules. Dependencies of MFI on the feedstock composition, metal-to-polymer ratio, type and content of additives, and particle size distribution of the metallic phase were established. The optimal feedstock formulation was determined experimentally. The microstructure and physical properties of sintered samples produced from the developed feedstock were evaluated and compared with those made from imported Catamold^® feedstock. It was demonstrated that standard heat treatment modes are suitable for MIM-fabricated parts, as the phase transformation behavior of the studied steel does not differ from that of conventionally processed materials. The results confirm that components manufactured from the in-house feedstock comply with relevant regulatory standards and match the performance of their imported counterparts.

Refractory ceramic composite materials of the silicon nitride–silicon carbide (Si₃N₄–SiC) system possess a wide range of valuab­le properties and are used across various industrial fields as excellent refractories, structural heat-resistant materials capable of withstanding high mechanical loads at elevated temperatures, and lightweight functional materials for microwave radia­tion shielding in aviation and aerospace applications. The performance of Si₃N₄–SiC composite ceramics can be significantly enhanced by increasing the dispersion of the component powders, transitioning from micron-sized particles to highly dispersed powders (<1 µm). This study focuses on improving a simple, energy-efficient method of azide self-propagating high-temperature synthesis (SHS) for obtaining such highly dispersed powder compositions, using mixtures of sodium azide (NaN₃) with elemental silicon and carbon powders, activated and modified by carbiding addition of powdered polytetrafluoroethylene (PTFE). These charge compositions, in both bulk and pressed forms, were combusted in a nitrogen atmosphere at 3 MPa. The maximum pressure and solid product yield were measured. The phase composition and microstructure of the combustion products were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The introduction of PTFE as a reactive carbiding and activating additive effectively overcame the limitations of conventional azide SHS processes that use halide salts such as NH₄F, Na₂SiF₆, and (NH₄)₂SiF₆. In addition to ensuring a high dispersion of the synthesized powders, the phase composition – particularly for the pressed charges – became significantly closer to the target theoretical composition. Notably, the silicon carbide content in the Si₃N₄–SiC product increased substantially, while the amounts of free silicon and carbon impurities decreased.

In the present work, sintering and investigation of composite ceramic materials based on nanostructured MgO–ZrO₂ powders were carried out. Zirconium dioxide was additionally stabilized with 3 mol. % yttrium oxide. The nanopowders were pre-treated by mechanical activation using a planetary ball mill at a rotation frequency of 10 Hz. Zirconium dioxide balls were used as the grinding media. The prepared powders were compacted at pressing pressures of 50, 100, 200, and 300 MPa. The compacts were sintered in a high-temperature furnace at 1700 °C. Microstructural studies were performed on the polished surfaces of the sintered samples using scanning electron microscopy (SEM). EDX mapping was conducted to determine the elemental distribution, confirming the presence of two phases in all samples. To evaluate the effectiveness of stabilizing additives on the polymorphic transformation of zirconium dioxide, X-ray diffraction (XRD) analysis was performed. The porosity of the materials and its dependence on the pressing pressure and magnesium oxide content were also assessed. Mechanical properties such as Martens hardness and elastic modulus were measured using a NanoIndenter G200, while flexural strength was evaluated by scratch testing on the same device. Fracture toughness was determined by the indentation method using the Marshall–Evans approach. The influence of magnesium oxide additives on the physical and mechanical properties of the MgO–ZrO₂ composite ceramics was established.

A two-layer coating with a total thickness of approximately 15 μm was obtained using a combined technology of electrospark deposition (ESD) and high-power impulse magnetron sputtering (HiPIMS), employing HfSi₂–HfB₂–MoSi₂ ceramic electrodes/target on a niobium substrate. The formation mechanism, morphology, and structure of the coatings were investigated using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was found that the ESD coating consists of 65 wt. % phases formed through interaction between the electrode and the substrate – namely NbSi₂ and Nb₅Si₃ – and exhibits a silicon concentration gradient (from 8 to 54 at. %) across the coating thickness, from the substrate toward the surface. The outer amorphous HiPIMS coating is ~5 μm thick. Analysis of structural and phase transformations during heating of the ESD coatings up to 900 °C showed that annealing leads to its separation into two layers: an inner layer composed of dendritic grains of the metastable γ-Nb₅Si₃ phase and an outer layer based on NbSi₂. The HiPIMS coating crystallizes sequentially, forming (Hf,Mo)B₂ at 700 °C, MoSi₂ at 800 °C, and Hf₃Si₂ and HfSi₂ at 900 °C, with the silicon content remaining virtually unchanged. As a result of the two-stage deposition process and subsequent high-temperature annealing, a multilayer protective ceramic coating was obtained, consisting of an outer layer of (Hf,Mo)B₂–MoSi₂–HfSi₂, an intermediate layer of NbSi₂, and an inner layer of Nb₅Si₃, with hardness values of 9.4, 23.3, and 19.4 GPa, respectively. This coating significantly extends the service life of niobium grade Nb-1.

This article focuses on the production of wear-resistant antifriction coatings by magnetron sputtering using composite SHS-fabricated cathode targets of TiCrNiC and TiCrNiC–CuSnP in Ar and Ar + 15 % N₂ atmospheres. Special attention is given to the phase composition and structure of the targets, produced via the self-propagating high-temperature synthesis (SHS) method. Structural charac­terization of the targets and coatings was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and glow discharge optical emission spectroscopy (GDOES). The mechanical and tribological properties of the coatings were evaluated using nanoindentation, scratch testing, and pin-on-disk sliding wear tests. The resulting coatings exhibi­ted dense, defect-free microstructures with a uniform elemental distribution through the thickness. The coating matrix was primarily composed of FCC phases c-TiC(N) and c-(Ni,Cr). The addition of copper to the coating led to the formation of an additional amorphous Cu-based phase. The coatings demonstrated hardness in the range of 18–21 GPa and an elastic modulus of 220–235 GPa. High critical loads for adhesive failure were observed, reaching up to 60 N. The non-reactive Ti–Cr–Ni–C coatings exhibited the lowest friction coefficients (0.17–0.18), while other compositions showed values ranging from 0.22 to 0.25, in contrast to 0.63–0.71 for uncoated steel substrates. The specific wear rate varied between 1.1·10^–6 and 5.0·10^–6 mm³/(N·m) depending on the counterbody material and coating composition, which is nearly two orders of magnitude lower than that of the substrate material ((1.2÷2.7)·10^–4 mm³/(N·m).