Effects of current density and particle concentration on the properties of jet-electrodeposited Ni–Co–TiC composite coatings

To further enhance the mechanical properties of metal surfaces, Ni–Co–TiC nanocomposite coatings were successfully fabricated on 304 stainless steel substrates utilizing a custom-built jet electrodeposition system. This study systematically investigated the effects of cathodic current density and TiC particle concentration in the electrolyte on the growth kinetics, microstructural morphology, phase composition, crystallite size, microhardness, and tribological properties of the composite coatings. The results indicate that as current density and TiC particle concentration increase, the mass deposition rate, compactness, and mechanical properties of the coatings initially improve before subsequently declining. Under the optimal processing parameters (a current density of 70 A/dm 2 and a TiC particle concentration of 10 g/L), the high-velocity impingement of the jet flow and the electric field force achieved an optimal synergy. This effectively suppressed nanoparticle agglomeration and facilitated the uniform dispersion of TiC within the Ni–Co matrix. X-ray diffraction analysis verifies that the Ni–Co matrix retains a face-centered cubic solid solution structure, and the average crystallite size is refined to 15.2 nm under the optimized condition. Driven by the combined mechanisms of grain refinement and Orowan dispersion strengthening, the optimized coating reaches a peak microhardness of 654.24 HV and reduces the average friction coefficient to 0.265, achieving a favorable balance between mechanical strength and tribological performance. This study elucidates the regulatory mechanisms of jet electrodeposition parameters on the microstructural and macroscopic properties of composite coatings, providing a crucial theoretical basis for the engineering fabrication of high-performance, wear-resistant composite coatings.