Improvement Effect of TiO2 Sol Nanoparticles on the Tribological Behavior of Ni-B Coating

Ni-B coatings, elaborated through the electrodeposition process, are hopeful solutions for serviceable coating intended for heavy loading thanks to their superior microstructure characteristics, higher hardness and good wear resistance. To further enhance their mechanical and tribological behavior, in-situ formed Titania (TiO2) nanoparticles were added into Ni-B coating via the electrodeposition technique associated with sol-gel route. New Ni-B-TiO2 sol coatings were developed on heat-treated AISI P20 steel. The influence of Titania nanoparticles on the mechanical characteristics and wear resistance of Ni-B coating was evaluated. Seeking an optimum Titania sol amount added into the electroplating solution was also a challenge to produce a promising Ni-B-Titania composite coating. The micro-indentation test measured the microhardness and Young’s modulus of the coating and revealed the impact of Titania nanoparticles on promoting the adhesive strength of the Ni-B coating/substrate interface. Furthermore, a pin-on-disk test was conducted to investigate the tribological behavior of coatings. The obtained results are interesting and show an enhancement of Ni-B wear endurance. The best wear resistance of the Ni-B-TiO2 composite coating was identified at the optimum Titania sol concentration of 25 ml/L.