Arc spraying is one of the most effective and cost-efficient thermal spraying technologies for creating high-quality protective coatings. This paper examines the influence of arc spraying process parameters on the properties of steel coatings. The parameters varied in this study included gas pressure, wire feed rate, and the distance from the spray gun to the substrate (standoff distance). Experimental evaluations focused on surface roughness, thickness, porosity, structure, and hardness of the coatings. The techniques used for these evaluations included profilometry for roughness measurement, scanning electron microscopy (SEM) for structural analysis, Vickers hardness testing, and optical microscopy. The results demonstrate a significant influence of arc spraying parameters on the characteristics of the resulting coatings. The analysis revealed that the coatings produced under different modes exhibit a layered structure and vary in thickness. A detailed examination of the coating structure identified defects such as unmelted particles, voids, and delamination in the interface zone. The study of coating thickness and porosity showed that increasing the wire feed rate and decreasing the standoff distance leads to the formation of thicker and denser coatings. Specifically, increasing the wire feed rate from 2 to 12 cm/s resulted in a decrease in porosity from 12.59% to 4.33% and an increase in coating thickness to 699 μm. The surface analysis highlighted the importance of a comprehensive approach to selecting the optimal roughness. While increasing the wire feed rate up to 12 cm/s can increase the Ra roughness parameter, gas pressure also significantly influences this parameter, reducing roughness from Ra = 18.63 μm at 6 MPa to Ra = 15.95 μm at 8 MPa. Additionally, it was found that varying the arc spraying parameters affects the hardness of the coatings, with all modes resulting in hardness values higher than that of the substrate. Therefore, optimizing these parameters enables the achievement of the best combination of mechanical and structural properties in the coatings. These findings can be valuable for further improvement of arc spraying technologies and the expansion of their application across various industries.

In the present work, the effect of the composition of the metal binder (Co–Cr, Ni, and NiCr) on the structure and performance properties of WC-based coatings obtained by detonation spraying is investigated. The coatings were characterized using microstructural analysis, EDS mapping, microhardness measurements, tribological testing, and corrosion analysis. The results show that changing the type of binder significantly affects the porosity, distribution of the WC phase, hardness, and tribological behavior of the coatings. The best combination of properties—the lowest coefficient of friction, highest hardness, and the highest corrosion resistance—was obtained for the WC–Co–Cr coating. These results indicate the potential of these coatings for extending the service life of pipeline fittings and equipment in the oil and gas sector.

This study investigates the structural formation and performance characteristics of coatings produced by electric arc spraying using 20Kh13 steel wire on a 45 steel substrate with an adhesive interlayer made of 30KhGSA steel. Particular attention is paid to the effect of spraying air pressure (0.4–0.6 MPa) on the morphology, phase composition, microhardness, elastic modulus, and tribological properties of the resulting coatings. Microstructural and X-ray phase analyses revealed that increasing air pressure leads to higher coating density, reduced porosity (~2–3%), and increased content of the Fe₃O₄ oxide phase. Nanoindentation tests showed that the highest microhardness (up to 270 HV) and elastic modulus values were observed at 0.4 MPa, while the greatest structural integrity and stable frictional behavior were achieved at 0.6 MPa. Under both dry and lubricated conditions, the coatings exhibited stable performance and a low coefficient of friction (0.10–0.12 in oil), confirming the potential of the developed technology for the restoration and strengthening of component surfaces operating under combined loading and aggressive environmental conditions.

This study investigates the technological parameters of electric arc metallization applied to 30KHGSA steel, focusing on the effects of varying the spraying distance (100–250 mm) and gas pressure (6–9 Pa) on the resulting coating structure and properties. The spraying was performed using an SX-600 electric arc metallizer. Electron microscopy and metallographic analysis revealed that the coatings possess a layered structure consisting of solidified convective metal flows, micro-welded particles, and oxide inclusions. The optimal spraying parameters–150 mm distance and 7 Pa pressure–yielded the maximum coating thickness (729.58–733.62 μm) and the lowest porosity (4.02–4.33%). It was observed that increasing the spraying distance beyond 150 mm leads to reduced coating thickness, while deviations from the optimal gas pres sure result in decreased structural density and homogeneity. Electric arc metallization of 30KHGSA steel under optimal conditions enables the formation of coatings with enhanced wear resistance and mechani cal strength. Specifically, spraying distances over 150 mm and pressures outside the 7–8 Pa range nega tively affect the coating’s density, uniformity, and tribological performance. The identified optimal range (150–200 mm, 7–8 Pa) promotes the development of coatings with low surface roughness, reduced friction coefficient, and improved wear resistance. Key words: arc spraying, steel coatings, microstructure, Vickers hardness, porosity, thickness

The paper presents a comparative analysis of technologies for forming metal-ceramic coatings of WC-NiCr, Cr₃C₂-NiCr, and Al₂O₃-NiCr systems obtained by high-velocity oxygen fuel (HVOF) and detonation spraying methods. The aim of the study was to determine the influence of the coating technology on the microstructure, physical-mechanical and tribological properties of the coatings. The study included analysis of the morphology of the starting powders and the microstructure of the coatings using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Microhardness was determined using the FISCHERSCOPE HM 2000 system, and tribological characteristics were studied using the ball-on-disc method on an Anton Paar TRB³ tribometer in accordance with ASTM G133-95 and ASTM G99 standards. It was found that the spraying method has a significant effect on the structure and performance characteristics of coatings. For carbide systems (Cr₃C₂-NiCr and WC-NiCr), the HVOF method is more effective, providing the formation of a dense, fine-grained structure, increased hardness, and a reduced friction coefficient. For the Al₂O₃-NiCr oxide system, detonation spraying proved to be preferable, providing higher hardness and stable tribological characteristics. The results obtained allow for a reasonable choice of coating formation technology depending on their composition and operating conditions.

The hardness and post-scratch surface morphology of Cr₃C₂–NiCr coatings subjected to ultrasonic nanocrystal surface modification (UNSM) were examined for detonation-sprayed (DS) and high-velocity oxy-fuel (HVOF) deposits. Four treated samples per deposition route were evaluated at static loads of 20 and 30 N and vibration amplitudes of 20 and 30 µm. Instrumental hardness was measured at a load of 300 mN with a dwell time of 10 s. The DS samples exhibited hardness values of 820–970 HV, whereas the HVOF samples covered the wider range of 546–1165 HV. The highest values were recorded for DS-T1 at 20 N/20 µm and HVOF-T4 at 30 N/30 µm. SEM fields acquired after scratch testing showed heterogeneous surface contrast and crack-like discontinuities in both coating series. These observations provide qualitative evidence of the post-test surface condition but do not isolate damage caused by UNSM or establish a ranking of scratch resistance. Available mean friction coefficients are reported as supplementary observations for six treated samples. The results demonstrate a sample-dependent hardness response and emphasize the need to assess local mechanical properties together with surface integrity.