Improvement of Mechanical and Tribological Properties of Nickel-Aluminium Oxide Coating by Jet Electrodeposition

Introduction: Jet electrodeposition technology has proven effective for enhancing metal substrate surface properties. This study employed the technique to fabricate Ni- Al2O3 composite coatings on stainless steel substrates, aiming to improve their mechanical performance and tribological characteristics. Methods: The Ni- Al2O3 coating was generated by using the univariate control method and changing the parameters of current density and Al2O3 concentration, respectively. Comprehensive characterization was performed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) for microstructural analysis, while microhardness and wear resistance were systematically evaluated using a Vickers hardness tester and reciprocating tribometer, respectively. Results: Through systematic optimization of deposition parameters, optimal performance was achieved at a jet velocity of 150 L/h, current density of 130 A/dm², and Al2O3 concentration of 20 g/L. The resulting coatings exhibited exceptional mechanical properties, including a maximum hardness of 547 HV, a remarkably low friction coefficient of 0.14, and minimal wear loss (0.6 mg). Discussion: The performance enhancement is mainly due to the fact that at the optimal current density, this density balances the cathode overpotential, promotes grain refinement, and simultaneously avoids concentration polarization and tip effects. This synergistic effect is further amplified by the incorporation of Al2O3 nanoparticles, which refine Ni-based particles by increasing nuclear sites, serve as the carrier hard phase, and provide abrasive polishing during the deposition process. However, excessive Al2O3 can cause particle agglomeration, reduce the uniformity of the microstructure, and thereby lower the performance of the coating. Forced convection in jet electrodeposition is crucial for maintaining the dispersion of nanoparticles. Conclusion: This study successfully determined optimal jet electrodeposition parameters for highperformance Ni- Al2O3 coatings. The resulting coatings exhibit excellent mechanical and tribological properties. The method's scalability and performance suggest strong commercial patentability in wear-resistant coatings.