THE EFFECT OF THE COMPOSITION OF METAL-CERAMIC POWDERS ON THE STRUCTURE AND PERFORMANCE PROPERTIES OF COATINGS OBTAINED BY THE HVOF METHOD

Аңдатпа

The article presents the results of a comprehensive study of WC–Co–Cr, WC–NiCr, WC–Ni, Cr₃C₂–NiCr, and Al₂O₃–NiCr cermet coatings deposited onto a 65G steel substrate by the high-velocity oxy-fuel (HVOF) spraying method. An analysis of the microstructure (SEM/EDS), microhardness, surface roughness, tribological characteristics, and adhesive strength of the coatings was carried out. It was established that the composition of the powder mixture and the characteristics of the binder phase significantly affect the formation of the structure and performance properties of the coatings.

The WC–Co–Cr coating formed the densest and most structurally homogeneous lamellar structure, demonstrating the lowest coefficient of friction (μ = 0.143), the highest microhardness (1316.87 HV), and high resistance to scratch loading. The Cr₃C₂–NiCr and WC–NiCr coatings showed satisfactory tribological characteristics (μ = 0.310 and 0.326, respectively); however, reduced adhesive strength was observed for the Cr₃C₂–NiCr coating. The WC–Ni coating was characterized by an increased coefficient of friction (0.545) at moderate hardness values (721.2 HV). The highest coefficient of friction was found for the Al₂O₃–NiCr coating (0.630), while this system also demonstrated the lowest microhardness (631.59 HV) and instability in structure formation.

The surface roughness of the coatings was in the range of Ra = 3.881–8.130 μm and depended on the spraying conditions. The obtained results made it possible to determine that the WC–Co–Cr coating provides the optimal combination of mechanical and tribological properties and is the most promising for application under conditions of intensive abrasive-adhesive wear in mechanical engineering, power engineering, and metallurgy.