This study investigated the properties of a composite NiCrFeSiB coating with fine-dispersed WC additives, deposited by the HVOF method. The NiCrFeSiB powder alloy with WC additives was applied to a steel substrate. The WC content in the coating was 10, 15, and 20% by weight. The particle size distribution of the mixture ranged from 3 to 10 µm. The WC used was the WC8 alloy (92% WC, 8% Co). The levels of stress, phase composition, hardness, wear resistance, and coating structure were investigated. The studies revealed that the structure was primarily composed of the γ-Ni-Fe solid solution phase, with secondary phases including Ni₃B, Fe₃B, (Cr,)₂B, and carbides of the W₂C, WC, M₇C₃ type. A small amount of the initial WC particles was also present. The use of a fine-dispersed NiCrFeSiB powder mixture with WC particles resulted in a nearly twofold increase in hardness and wear resistance compared to the same parameters of the coating without WC. The coating with 20% WC exhibited the highest hardness. However, its wear resistance was lower than that of the coating with 15% WC. This fact could be explained by a slight difference in the phase composition and an increase in the proportion of the unsolidified WC phase in the structure. This led to the spalling of fine particles and a reduction in wear resistance. The study demonstrated the feasibility of using a fine-dispersed NiCrFeSiB coating with WC additives without additional remelting. Similar hardness and wear resistance results were achieved immediately after HVOF spraying when using a fine-dispersed NiCrFeSiB + 15% WC/Co mixture with a 92/8 composition. This simplification of the technology reduced the coating application process time. It also lowered production costs by eliminating the remelting stage.

The growing demand for improved operational efficiency of cast components used in various types of equipment necessitates the development of advanced casting technologies. One of the key challenges currently faced by the foundry industry is enhancing the surface quality of castings and reducing rejection rates caused by casting defects. These requirements can be effectively met by castings produced using shell mold casting technology. Sand–resin mixtures are used for their production. Foundry molds made from such mixtures make it possible to obtain high-quality castings from various alloys. However, their widespread industrial application is limited by the relatively high cost of the binder, namely pulverbakelite. The influence of pulverbakelite content on the properties of sand–resin mixtures during shell mold formation under variational static pressure was investigated. It was established that pressure variation during the molding process increases mold strength and improves surface quality while maintaining the required level of gas permeability. The optimal binder content was determined to be 4–6%, which makes it possible to reduce binder consumption without deteriorating the mechanical and technological characteristics of the mold. With respect to novelty, it should be noted that previous studies addressed individual aspects of variable pressure application. In the present article: a wider range of pulverized bakelite content (3–9%) was investigated; the relationship between binder content, strength, and gas permeability was established; the optimal binder content range (4–6%) was determined; and microstructural analysis was extended to include composition and pressure regimes. Thus, the present work significantly extends previous findings and provides a more comprehensive investigation.

The results of the study of the effect of molybdenum on the structure and properties of the quasi-high-entropy alloy (QHEA) of the Fe-Co-Cr-Ni-Mn-Nb system are presented in this paper. Together with pure metals, ferroalloys were also used in smelting experimental alloys. Due to pure metals and ferroalloys, the obtained experimental alloys were called QHEA in contrast to HEA (high-entropy alloys). It was found that solid solutions of the FCC type (Mn, Fe, Co, Ni) and ICC type (Nb, Mo), σ-phase (Cr, Mo), carbides Cr3C7, (Nb, Mo)C and Laves phases (Nb, Mo)(Fe, Ni, Mn)2 were formed in the final structure of the studied samples. For the first time, the presence of such phases as carbides Cr3C7 and (Nb,Mo)C was established in the alloy structure, which were not described in similar studies devoted to the effect of molybdenum on the properties of alloys of the Fe-Co-Cr-Ni-Mn-Nb system. Adding Mo in 5-15% by weight increased the hardness from 243 HV to 689 HV and the strength from 550 MPa to 980 MPa without changing the ductility values.