Tribological properties of Mo-S-I nanowires as additive in oil

A new nanowire-like material with the chemical formula Mo6S4.5I4.5 was studied as additive in a synthetic base oil, a polyalphaolefin (PAO). This material presents interesting friction reducing properties, with friction coefficients reaching a value of 0.04 in boundary lubrication. Transmission and scanning electron microscopy, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy were used to characterise nanowires before and after friction. The combination of these techniques gave evidence of MoS2 formation in the contact area during friction tests. This structural evolution of nanowires explains their good friction reducing properties.