Characterization and frictional behavior of nanostructured Ni-W-MoS2 composite coatings

Ni-W-MoS2 composite coatings were obtained by pulse plating from a Ni-W electrolyte containing suspended MoS2 particles. The coating composition, morphology, crystalline structure, microhardness and frictional behavior were studied as a function of MoS2 concentration. The results obtained in this study indicate that co-deposited lubricant particles strongly influenced the composite Ni-W coating properties. It was found that increasing co-deposited MoS2 diminished tungsten content in the coating and consequently increased the average grain size. Ni-W nanostructured coatings with high MoS2 content have a porous sponge-like structure, high surface roughness and irregular frictional behavior. However, the friction coefficient of Ni-W coatings is reduced to half its value with low MoS2 content. (C) 2009 Elsevier B.V. All rights reserved.