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 Lamps 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 Horse Combs 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).