Development of a Method for Producing Self-Fluxing Nickel-Based Coatings by Detonation Spraying

Abstract

This study investigated the influence of detonation spraying parameters on the structure and tribological and mechanical properties of self-fluxing coatings of the Ni–Cr–Fe–B–Si–C system. The investigated parameters included the barrel filling level (48–68%), the molar ratio of the working gases (O/C = 1.026–1.856), and the inter-shot delay (0–1 s). Morphological analysis of the coatings revealed a characteristic lamellar structure and a dependence of coating thickness and defect formation on the spraying conditions. A lower barrel filling level resulted in a denser coating structure with minimal porosity, whereas medium and high filling levels promoted the formation of microcracks, presumably due to increased residual stresses. Tribological tests showed that the minimum coefficient of friction was obtained at a barrel filling level of 48% (μ = 0.674 ± 0.136) and an O/C ratio of 1.026, but these conditions were also associated with increased wear. The highest wear resistance was obtained at an O/C ratio of 1.856 and an increased inter-shot delay of up to 1 s, resulting in a decrease in the specific wear rate to 0.000189 mm³/(N·m). Roughness analysis showed that increasing the inter-shot delay reduced Ra from 5.00 to 3.60 μm, which may be attributed to a reduction in thermal load and more favorable coating formation conditions. The maximum hardness, up to 905.6 HV, was obtained for a combination of parameters that promoted the formation of a dense structure and strengthening phases. The results indicate that optimizing the detonation spraying parameters requires a trade-off between reducing the coefficient of friction and increasing wear resistance. The findings can be used to develop tech nologies for the restoration and surface strengthening of machine components.