Effect of electrodeposition conditions and reinforcement content on microstructure and tribological properties of nickel composite coatings

In this work, pure nickel and nickel composite coatings (Ni–Al2O3, Ni–SiC, and Ni–ZrO2) were deposited from Watts bath using direct current (DC), pulsed current (PC), and pulsed reverse current (PRC) electrodeposition conditions. Detailed investigations on the effect of deposition conditions on the evolution of surface microstructure, crystallographic micro-texture, microhardness, and sliding wear behavior of pure nickel and nickel composite coatings are presented. For all the coatings, the PC and PRC deposition conditions resulted in more random/weak crystallographic texture compared to DC deposition. The composite coatings deposited using PC and PRC deposition also exhibited significant improvement in microhardness and wear resistance due to enhanced reinforcement of nanoparticles in the coatings. Also, the effect of nanoparticle content of the electrolyte bath on the surface microstructure, tribological properties, and level of reinforcement in the Ni–Al2O3 composite coating is investigated. The reinforcement of nanoparticles in the Ni–Al2O3 composite coatings increased linearly with the amount of nanoparticle loading in the electrolyte bath. The microhardness and wear resistance of the Ni–Al2O3 composite coatings also improved with increasing Al2O3 content in the coatings.