The Role of Kinematic Viscosity of White Oil in FLC-oil Lubrication System

A hydrogenated fullerene-like carbon (FLC) film was prepared by dc pulse plasma-enhanced chemical vapor deposition technique. The wetting, friction and wear behaviors of FLC film with industrial white oils were investigated, and the influence of kinematic viscosity (5~150 mm²/s) of white oil on such a solid-liquid lubrication system was also analyzed. The results show that the lower the kinematic viscosity was, the better the wettability of FLC film showed. And with the rise of kinematic viscosity, the molecular weights and chain lengths of white oils kept an upward tendency, the oil-film coherency was strengthened and the oil-film thickness was grown up, therefore the friction of FLC film reduced significantly and the friction coefficient reached its lowest value (0.114) at 32 mm²/s. However, when the increasing of kinematic viscosity was going on, the rising of friction occurred instead, which was due to the increment of viscous or friction drag in solid-liquid composite lubrication system. At the same time, the wear rate of FLC film continuously decreased, but the variation was not obvious when the kinematic viscosity was larger than 26 mm²/s.