Boundary Lubrication Characteristic of Metal-Containing Diamond-Like Carbon (DLC) Films with Poly Alpha Olefin (PAO) Lubricant

Abstract

The effects of metals such as cobalt (Co), cerium (Ce), magnesium (Mg), nickel (Ni) and titanium (Ti) added to diamond-like carbon (DLC) films on boundary lubrication properties were investigated using a ball-on disk tribometer. The boundary lubrication properties of metal-containing DLC films are improved compared with those of DLC films without metal under poly alpha olefin (PAO) lubricant with and without glycerol mono-oleate (GMO) additives. Moreover, under boundary lubrication using PAO with GMO, DLC films with an appropriate quantity of Co-added show the lowest friction coefficient of μ= 0.02 among all the tested metal-containing DLC films. The friction product layers were formed on the sliding surface of Co-containing DLC films. Lower-nanofriction layers formed on the sliding surface were observed by force modulation methods of atomic force microscopy (AFM).