Effect of Laser Remelting on the Microstructure, Mechanical and Tribological Properties of Detonation-Sprayed NiCrFeBSiC Coatings for Mechanical Engineering Applications

This study investigates the effect of laser remelting on the microstructure, phase composition, mechanical properties, tribological behavior, and corrosion resistance of self-fluxing NiCrFeBSiC coatings deposited onto AISI 321 stainless steel by detonation spraying. The coatings were characterized before and after laser treatment using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), instrumented indentation, adhesion testing, ball-on-disk tribometry, and potentiodynamic polarization measurements. SEM analysis revealed that laser remelting reduced coating porosity from 0.306 ± 0.014% to 0.15 ± 0.09%, accompanied by microstructural densification and a reduction in coating thickness. XRD analysis confirmed the preservation of the principal crystalline phases, including Ni3Fe, Cr7C3, CrB, and Ni3B, following laser treatment. The Vickers hardness increased from 1049.1 ± 43.4 to 1206.1 ± 63.1 HV, while the elastic modulus increased from 233.6 ± 6.2 to 258.4 ± 5.3 GPa. Furthermore, adhesion strength increased by 19.4%, whereas surface roughness decreased by 19.2%. Laser remelting significantly improved tribological performance, reducing the average coefficient of friction from 0.535 ± 0.048 to 0.409 ± 0.086 and the specific wear rate from 2.864 × 10−4 to 1.447 × 10−4 mm3/(N·m), corresponding to a 49.5% reduction in wear. Electrochemical measurements indicated a modest decrease in corrosion current density of approximately 3.0%, accompanied by changes in the morphology of corrosion-affected regions. The improvements are associated with laser-induced microstructural densification, redistribution of alloying elements, and preservation of hard reinforcing phases. These findings demonstrate the potential of combining detonation spraying with laser remelting to produce wear-resistant nickel-based protective coatings for mechanical and power engineering applications.