Electrodeposited nickel-cobalt composite coating containing MoS2

Ni-Co/MoS2 composite coatings were prepared by electrodeposition in a Ni-Co plating bath containing nano-sized MoS2 particles to be co-deposited. The polarization behavior of the composite plating bath was examined on a PAR-273A potentiostat/galvanostat device. The friction and wear behaviors of the Ni-Co/MoS2 composite coatings were evaluated with UMT-2MT test rig in a ball-on-disk contact mode. The morphologies of the original and worn surfaces of the composite coatings were observed on scanning electron microscope (SEM). It was found that the introduction of MoS2 nano-particulates in the electrolyte caused the shift towards larger negatives of the reduction potential of the Ni-Co alloy coating, and the co-deposited MoS2 showed no significant effect on the electrodeposition process of the Ni-Co alloy coating. However, the co-deposited MoS2 led to changes in the surface morphology and structure of the composite coating as well. Namely, the peak width of the Ni-Co solid solution for the composite coating is broader as compared to that of the Ni-Co alloy coating. The co-deposited MoS2 particulates were uniformly distributed in the Ni-Co matrix and contributed to increase tribological properties of the Ni-Co alloy coating.