Abstract
The study investigates the effect of powder feed rate on the thermal deposition conditions, microstructure, and performance properties of Cr3C2-NiCr coatings produced by high-velocity oxy-fuel (HVOF) spraying onto copper alloy substrates used for continuous casting mold applications. It is shown that variations in powder feed rate determine the balance between the thermal power of the gas jet and the mass flow of the sprayed material, thereby influencing the degree of particle heating and melting during spraying. Microstructural analysis using scanning electron microscopy revealed that the powder feed rate significantly affects the lamellar structure density and porosity level of the coatings. At an optimal powder feed rate, coatings with a homogeneous microstructure and minimal porosity are formed. Such coatings exhibit higher microhardness, reduced surface roughness, and a stable coefficient of friction. The results demonstrate that optimization of the powder feed rate is an effective approach for controlling the structural, mechanical, and tribological properties of coatings intended for operation under severe thermal and mechanical conditions.