Effects of Heat Treatment on the Tribological Behavior of Ni-SiOC Nanocomposite Coatings

Abstract

Amorphous-ceramic-reinforced-metals (ACRMs) have excellent mechanical properties across a wide temperature range, which holds great promise as wear-resistant coatings under complex service conditions. Recent studies show that proper annealing results in enhanced tensile strength and ductility of ACRMs due to microstructure evolution that promotes co-deformation between the amorphous and crystalline nanograins. The goal of this research is to understand how annealing affects the wear behavior of ACRMs, by linking the wear-induced deformation mechanisms to subsurface microstructural evolution. Specifically, co-sputtering of Ni, SiC and SiO2 targets with further post annealing at 600 ℃ and 800 ℃ was employed in the synthesis of Ni-SiOC ACRMs, comprising of submicron Ni matrix containing amorphous SiOC ceramic particles. Transmission electron microscopy (TEM) characterization revealed that annealing led to the growth of both the Ni and SiOC phases. Room temperature reciprocal wear test of both the as-deposited and annealed ACRM samples was performed under 1 N constant load using a 4 mm diameter alumina ball as counterbody, at 1 Hz frequency, 5 mm stroke distance for 10 mins. Wear rate decreased with increase in annealing temperature up to 600 ℃ before increasing with increase in annealing temperature. Post wear characterization revealed the refinement of the Ni and SiOC reinforcing phases, which serves as the basis for the discussion on the effects of annealing temperature on the wear-induced deformation mechanisms occurring in the nanocomposite.