Manufacturing waste can be not only recycled but also utilized as a source of chemical elements and as a component of powder materials. Steel swarf are a complex multicomponent material with a high iron content, while impurities such as carbon can affect the diffusion interaction in the chip and metal powder mixture. In this study, we investigate the diffusion interaction between aluminum and steel swarf using temperature-controlled vacuum sintering. We analyzed the resulting mixture’s microstructure and phase composition, and observed that sintering creates a multiphase structure in which FeAl iron aluminide occupies at least 30 vol. %. Despite the high sintering temperature, we also observed residual aluminum and iron. Incomplete transformation may result form refractory products that inhibit diffusion or impurities that influence the magnitude and direction of the diffusion fluxes. To confirm the impurities’ role in the diffusion interaction kinetics, we developed simulation models of the intermetallic phase growth for a flat and spherical particle embedded in aluminum. The model consider cross-diffusion fluxes in the emerging phase regions and possible effects of impurities on the concentration limit for the new phase’s existence. We derived approximate analytical solutions to analyze the emerging phase growth trends under various model parameters.

This review presents a comprehensive analysis of the impact of tantalum alloying on the structure, heat resistance, and ablation resistance of ZrB₂(HfB₂)–SiC ultra-high-temperature composites. The influence of the primary phase content on the effects on the structural and morphological features of the oxide layers and their protective efficiency is analyzed. It is shown that alloying positively affects the composite's behavior by enhancing the viscosity and thermal stability of the glass phase, decreasing anionic conductivity, partially stabilizing the ZrO₂(HfO₂) lattice, and forming temperature-resistant complex oxides, such as Zr₁₁Ta₄O₃₂ or Hf6Ta₂O₁₇ on the surface. It has been established that the alloying can have negative effects, including an increase in the liquid phase content, oxide film discontinuity, ZrO₂(HfO₂) grain damage due to TaB₂ oxidation, or a significant amount of gas release due to TaC oxidation, as well as the formation of oxygen diffusion channels during the verticalization of Zr₁₁Ta4O₃₂ or Hf₆Ta₂O₁₇ platelets. It is essential to note that the oxidation and ablation resistance, as well as the mechanisms driving composite behavior, differ depending on the alloying compounds and test conditions. Overall, this study sheds light on the role of tantalum alloying in enhancing the performance of ZrB₂(HfB₂)–SiC UHTC and highlights the importance of understanding the underlying mechanisms that govern their behavior.

The results of the researching process of obtaining composition powder material B₄C–TiB₂ by carbide reduction of titanium dioxide, using carbon reducing agent – carbon nanofibers, are presented. Furthermore, the results of studying of some properties of ceramics made using the synthesized powder are presented. The synthesis of composite materials was carried out in an induction crucible furnace for 20 min in the temperature range of 1200–1900 °C in an argon atmosphere. It has been established that the optimum temperature of the synthesis is 1650 °C, irrespective of the batch composition. The characteristics of the composite powders containing 10–30 mol. % of the TiB₂ phase have been studied. X-ray electron microscopy has revealed that the particles of the powder are predominantly aggregated. There are two peaks in the particle size distribution histograms. The part of the histogram with a smaller particle size mainly characterizes the B₄C phase. The part of the histogram with a larger particle size characterizes the TiB₂ phase. The average particle size of the B₄C phase is in the range of 5.3–5.5 µm, and that of the TiB₂ phase is in the range of 33.6–41.9 µm. The average size of 50 % of composite powder’s particles for these contents does not exceed 13.4 μm. The surface area of the samples does not exceed 5 m²/g. The oxidation of the composite powder materials by atmospheric oxygen begins at a temperature of approximately 500 °C. At the same time, when the temperature reaches 1000 °C, no more than 45 wt. % of the studied powders is oxidized. Ceramics made with the synthesized powder mixture B₄C + 30 mol. % TiB₂ by hot pressing has shown rather high values of relative density (99.0±1.1 %) and fracture toughness (5.0±0.2 MPa∙m^0.5).

We investigated the influence of the basic component concentration on the microstructure of the KNT3 and KNT3 tungsten-free hard alloys (TFHA), focusing on ceramic-metal samples (cermets) with a low nickel-molybdenum binder content. The microstructure of the sintered cermets was analyzed using reflected electron images of thin sections obtained with a scanning electron microscope. Our analusis revealed that the KNT alloy exhobits a core/rim structure (CRM). We observed that decreasing the Ni–Mo binder content leads to a significantincrease in the rim size isurrounding the Ti(C, N) core in the sintered alloy. We also investigated the effect of the plasticizer on the formation of the core/rim microstructure with a low binder content. Furthermore, we found that the absence of nitrogen-enriched areas in the Ti(C, N) grains increases the molybdenum diffusion rate across the refractory phase interfaces during the cooling stage, resulting in a higher specific volume fraction of the shell in the cermet microstructure.

The paper shows the effect of solution temperature on the deposition rate of applying composite nickel-phosphorus coatings modified with boron nitride and polytetrafluoroethylene to powder samples made of improved P40, P40Kh and P40KhN steels obtained by hot stamping of porous sintered blanks. It has been experimentally established that within the range of 70–90 °C, the average deposition rate of modified BN and (C₂F₄)n coatings is 15–19 μm/h, while the chemical composition of the improved steels and the surface configuration of the samples have no effect on the coating build-up rate. The mechanism of the formation of the structure and properties of nickel-phosphorus coatings (NiPC) without additives and those of NiPC modified with boron nitride and polytetrafluoroethylene during deposition, sintering and running-in is revealed. It has been established that immediately after deposition, Ni–P coating has an amorphous structure with inclusions of nickel particles, and its microhardness does not exceed 380–390 MPa with no modifiers added. In the dry friction mode at the running-in stage, Ni₁₂P₅ and Ni₂P phases are formed in the modified Ni–P coatings, allowing to improve their tribological properties, and in the steady-state mode, the phase disordering of the modified NiPC proceeds. It has been experimentally revealed that the coefficient of friction and wear decrease by 1.3 times when only (C₂F₄)n is introduced into Ni–P coating, these indices decrease by 1.6 times when only BN is added, and they decrease almost twice when BN and (C₂F₄)n are introduced together. It has been established that upon the combined (complex) modification of NiPC with BN and (C₂F₄)n after the heat treatment, there is almost no nickel oxide phase, nickel boride of NiB type is formed in the coating during running-in, and its content does not decrease when entering the stationary friction mode, thus increasing tribotechnical properties of the coating. During running-in, the coefficient of friction of Ni–P + BN + (C₂F₄)n coating decreases from 0.28 to 0.19, and the wear rate of such a coating in the stationary friction mode is 1.5 mg/h. The efficiency of applying the antifriction nickel-phosphorus coatings modified with BN + (C₂F₄)n to the products made of the improved structural steels obtained by various methods has been theoretically and experimentally substantiated.

Ta–Zr–Si–B–C–N coatings were deposited by magnetron sputtering using a TaSi₂–Ta₃B₄–(Ta, Zr)B₂ composite target. Ar, as well as Ar + N₂ and Ar + C₂H4 gas mixtures, were used as the working gas. The structure and composition of the coatings were studied by scanning electron microscopy, glow-discharge optical emission spectroscopy, and X-ray diffraction. A Calowear tester was used to measure the thickness and abrasion resistance of the coatings. Erosion resistance tests were carried out using a UZDN-2T (Russia) ultrasonic disperser. Tribological tests in the sliding friction mode were carried out on an HT Tribometer (CSM Instruments, Switzerland) automated friction machine. The wear zone after tribological testing was examined using a Veeco Wyko 1100 (Veeco, USA) optical profiler. The results showed that the Ta–Zr–Si–B coating was characterised by a columnar structure with an h-TaSi₂ crystallite size of 11 nm. The introduction of nitrogen and carbon into the composition of the coatings led to the suppression of columnar growth and a ~2–4-fold decrease in the size of h-TaSi₂ crystallites. Carboncontaining coatings demonstrated the best abrasive resistance. The sliding friction tests showed that the Ta–Zr–Si–B coating is characterised by a stable coefficient of friction of 0.3 at a temperature of 25 °C up to the maximum working temperature of 250 °C. The introduction of nitrogen led to an increase in the coefficient of friction up to 0.8–1.0 at a t = 50÷110 °С. The coating with the minimum carbon concentration showed a stable coefficient of friction of ~0.3 up to a maximum temperature of 250 °C. The best result was demonstrated by the sample containing the maximum amount of carbon, with its coefficient of friction remaining at the 0.25 level up to a temperature of 350 °C.

The aerospace industry is currently undergoing a major trend of transitioning to composites. This study exanines the utilization of the magnetic field of rotating dipoles to produce high-strength iron powder-containing composites. The physical and mechanical properties of the modified epoxy composites were investigated through the use of SEM to analyze their microstructure and elemental composition, and a component distribution map was developed for the samples. Results indicate that the application of the magnetic field of rotating dipoles enhances the compression strength by 16.6 % relative to samples that were not exposed to it. Additionally, the magnetic field eliminates gas porosity and cavities formed during stirring. Tests conducted on composites with a higher content of Al particle showed that the magnetic field of rotating dipoles contributes to the release of excess aluminum as a surface layer. The use of the magnetic field of rotating dipoles is a promising technology for producing enhanced composites with superior physical and mechanical properties, which could potentially be used as structural material in aerospace industry or as adsorbing materials in microelectronics.