OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 3 2025 Ta b l e 3 Thickness, roughness and wettability of coatings Characteristics Sampels WCn WC20 WC40 Thickness, μm 25.19±5.78 24.35±5.68 26.13±6.10 Roughness, µm 8.23±2.17 6.73±0.89 5.87±0.94 Wettability, ° 77.7±1.6 83.6±1.6 82.7±1.6 that powders participate much more intensively in the formation of coatings during ESDNE compared to compact electrodes (granules). The surface roughness (Ra) of the coated samples ranged from 5.87 to 8.23 µm (Table 3). Furthermore, the contact angle with distilled water ranged from 77.7 to 83.6°, which is significantly higher than that of Steel 45 (54.1±1.4°). Thus, the application of WC/Fe-Ni-Al coatings to components made of Steel 45 will increase the hydrophobicity of their surface due to a reduction in surface free energy. This is expected to reduce the deposition of contaminants on the surface and, consequently, limit the development of corrosion on steel structures. The microhardness measurements on the coating surface revealed values ranging from 4.39 to 9.16 GPa, with the WCn sample exhibiting the minimum value and the WC20 sample exhibiting the maximum (Fig. 6). Thus, the application of coatings allows for a 1.7 to 3.6-fold increase in the hardness of products made of Steel 45. The low hardness values of the sample obtained using tungsten carbide nanopowder can be attributed to the absence of large tungsten carbide inclusions in its composition. Moreover, this coating had the lowest content of the W2C phase (30 GPa) [21]. The hardness of the WC20 and WC40 coatings was nearly identical, but significantly higher than that of WCn due to the higher content of the W2C phase. The results of friction tests on WC/Fe-Ni-Al coatings under a load of 25 N are shown in Fig. 7, a. During the initial 30 m of sliding, a sharp increase in friction force was observed, resulting from an increase in the contact area between the counter-surfaces due to running-in and smoothing out of roughness asperities. The friction coefficient curves of all coatings exhibited an ascending trend in the stable stage, while the friction force values of Steel 45 fluctuated around a constant value. This can be attributed to the increased surface roughness of the coatings (Table 3). Analysis of the friction coefficient curves revealed that the friction force noise level was significantly lower for all samples with WC/Fe-Ni-Al coatings compared to Steel 45. The average friction coefficient values of the coatings (0.73–0.83) were 6–18% lower than those of uncoated Steel 45 (0.88). This can be attributed to the anti-friction properties of WO3, which forms during oxidative wear of tungsten carbide [22]. In conclusion, the use of the proposed WC/Fe-Ni-Al coatings allows for the reduction and stabilization of the friction coefficient of components made of Steel 45. The wear resistance of the coatings was investigated at linear sliding speeds of 0.47 and 1.9 m/s under a load of 25 N. The wear rate of WC/Fe-Ni-Al coatings ranged from 0.61 × 10−6 to 10.91 × 10−6 mm3/ Nm at a speed of 0.47 m/s and from 0.30 × 10−6 to 2.70 × 10−6 mm3/Nm at a speed of 1.89 m/s (Fig. 7, b). Therefore, the wear resistance of the developed coatings was 5 to 80 times greater than that of the Fig. 6. Microhardness of the coating surface
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