Abstract
This study investigates the effect of oxygen pressure during high-velocity oxy-fuel (HVOF) spraying on the formation and structural-phase characteristics of ZrCN coatings deposited on 65G steel. The coatings were produced using the Termika-3 system under fixed parameters of fuel, air flow, and spray distance, with oxygen pressure varied in the range of 4.0-4.5 bar. X-ray diffraction analysis revealed that the main coating matrix consists of a Zr(C,N) solid solution with a face-centered cubic lattice (Fm-3m). Increasing the O₂ pressure leads to partial thermal decomposition of ZrCN and the formation of ZrC, ZrN, and oxide phases such as t-ZrO 2 . Oxygen enrichment of the coatings results in grain refinement and lattice parameter expansion. The microhardness of the coatings (a-c) reaches 1512-1857 HV, which corresponds to an approximately fivefold increase relative to the initial sample. Based on the obtained results, it was shown that regulating the oxygen pressure in the HVOF jet significantly affects the phase composition, morphology, and adhesion quality, providing an optimal combination of hardness, ductility, and thermal stability.