The influence of tungsten carbide particle size on the characteristics of metalloceramic WC/Fe-Ni-Al coatings

Introduction. The granulometry (particle size distribution) of the starting powders significantly influences the hardness and strength of compacted tungsten carbide (WC) metalloceramic materials, but this effect has not been extensively studied in the context of WC/Fe-Ni-Al coatings. The purpose of this work is to investigate the influence of the granulometry of the starting WC powder introduced into the non-localized electrode on the kinetics of mass transfer, chemical composition, cross-sectional microstructure of WC/Fe-Ni-Al coatings, and their corrosion and tribological properties. Methods. WC/Fe-Ni-Al coatings were deposited on 45 steel substrates using the electrospark deposition (ESD) method with a non-localized electrode. The electrode comprised iron granules (Ø = 4 mm), Ni and Al powders, and WC powders with varying particle sizes. X-ray diffraction (XRD) analysis revealed that the coatings consisted of tungsten carbide, tungsten semicarbide (W₂C), intermetallic phases (Al₈₆Fe₁₄), ferronickel (FeNi), and body-centered cubic (BCC) phases (AlNi, AlFe). Results and discussion. It was determined that, with an increase in the WC powder particle size fraction in the electrode, the coating matrix composition became enriched with aluminum, while the iron concentration decreased from 60 to 30 at.%. The lowest values for hardness, wear resistance, and oxidation resistance were observed for the sample obtained using WC nanopowder. The microhardness of the coating surface ranged from 4.39 to 9.16 GPa. The oxidation resistance of the coated samples at 700 °C increased monotonically with increasing WC powder particle size. The study found that the use of WC powder with a particle size fraction of 20 to 40 µm resulted in the best performance in terms of hardness, wear resistance, and oxidation resistance of the WC/Fe-Ni-Al coatings at 700 °C. The application of these coatings increased the oxidation resistance of 45 steel by 11.6 times and wear resistance by 44 to 80 times, suggesting their potential for use in high-intensity applications.