OBRABOTKAMETALLOV MATERIAL SCIENCE Vol. 27 No. 3 2025 The coatings were applied in an argon flow at a rate of 0.3 m3/hour to protect the electrodes from oxidation. The total coating time for one sample was 10 minutes. A more detailed description of the laboratory setup for automatic coating application using the ESDNE method with powders is given in the study [16]. The weight gain of the substrate was measured on a laboratory scale (Vibra HT120) (10−4 g) every 120 s of ESDNE treatment. The phase composition of powders and prepared samples was studied by X-ray diffraction. For this purpose, a multifunctional X-ray diffractometer DRON-7 (NPP Burevestnik, Russia) with Cu-Kα radiation (λ = 1.54056 Å) was used in this work. For metallographic examination of the microstructure and chemical microanalysis of samples with coatings, a scanning electron microscope Vega 3 LMH (Tescan, Czech Republic) equipped with a microanalyzer (EDS) X-max 80 (Oxford Instruments, UK) was used. The surface roughness of the coatings was measured using a 296 profilometer (USSR). For each sample, 10 roughness measurements were taken and average values were calculated. To determine wettability, the “sessile drop” method was used. A drop of distilled water was applied to the horizontal surface of the coating, and the contact angle with the surface at a temperature of 25 °C was determined from the drop profile [17]. For each sample, 5 measurements of wettability were performed, and average values were calculated. Microhardness was determined using the restored indentation method using a PMT3-M microhardness tester. Microhardness measurements were carried out using the Vickers method with a loading force of 1.96 N and an exposure time of 12 s. On each sample, 20 indentations were made, 20 measurements of the microhardness value were carried out, and the average values were calculated. Tests for the coefficient of friction and wear of samples were carried out using the “pin-on-disk” scheme [18–20] under a load of 25 N at speeds of 0.47 and 1.89 m/s for 10 minutes. Discs (d = 50 mm) made of high-speed steel M45 (60 HRC) were used as the counterbody. For each sample, at least 4 measurements were made, the average data sets were calculated, and the average values of the friction coefficient were determined. To determine wear resistance, at least 6 measurements were taken for each sample. To study cyclic oxidation resistance, samples of Steel 45 and samples with coatings that had a cubic shape with a 6 mm edge were used in the experiment. The samples were kept in a muffle furnace in cycles of ~6 hours at a temperature of 700 °C, and then placed in a desiccator to cool, and then weighed. The experiment was carried out for 100 hours. Results and Discussion When testing new compositions of non-localized electrodes, it is necessary to monitor the cathode weight gain during processing to establish the specific weight gain, as it characterizes the volume of material transferred to the substrate. Negative weight gain values indicate that a coating will not form. At the moments of voltage pulse application, electrical discharges occurred at the points of electrical contact between the granules and the substrate. This was accompanied by the transfer of metal from the melt pool of the granule to a pool on the surface of the substrate. Particles of Ni, Al, and WC powders located on the surface of the substrate or granules in the discharge impact area were wetted by the molten metal and incorporated into the melt pool on the substrate, forming a coating. With increasing processing time, the weight gain of the substrate gradually increased for all samples (Fig. 2, a). After 10 minutes of processing, the average values of the total specific weight gain of the cathode ranged from 2.74 to 4.76 mg/cm2, with the WC40 sample exhibiting the minimum value. The total weight gain values for the WСn and WС20 samples were very close, whereas the weight gain rate for W40 was noticeably lower. This may be due to the low specific surface area of large particles. The low surface area results in a lower specific surface free energy, which may not be sufficient for reliable particle attachment to the granule and cathode surfaces, potentially limiting the incorporation of such particles into the coating. X-ray diffraction (XRD) analysis revealed that the structure of the coatings contains tungsten carbide (WC), tungsten subcarbide (W2C), body-centered cubic (BCC) phases, an intermetallic compound (Al86Fe14), and an FeNi solid solution (Fig. 2, b). BCC phases may be represented by intermetallic compounds AlNi
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