Codeposition of inorganic fullerene-like WS2 nanoparticles in an electrodeposited nickel matrix under the influence of ultrasonic agitation

Abstract

Abstract The effects of ultrasound (US) agitation (at different intensities of ultrasound) on the codeposition of inorganic fullerene-like (IF) WS 2 in a metallic Ni matrix are investigated. The wt.% of IF-WS 2 particles in the nanocomposite coatings increases from 4.5 wt.% (in films grown under mechanical stirring but without US agitation) up to about 7 wt.% (in films prepared under US agitation at the optimum intensity of ultrasound). While composite coatings obtained only under mechanical stirring exhibit a rather irregular surface morphology, with pronounced 3D multinodular protrusions, a more uniform and compact coating is attained under application of US agitation. In turn, the introduction of WS 2 particles significantly modifies the growth of Ni, inducing grain size refinement, increasing the stacking fault probability and causing a drastic change of crystallographic texture. These microstructural features act in a synergistic manner to simultaneously increase the hardness of the composite coatings while causing the expected decrease in the friction coefficient (due to the presence of WS 2 solid lubricant particles), therefore enhancing the wear resistance, particularly when the coatings are deposited under the presence of US.