Preparation of surface modified lanthanum trifluoride powder and investigation of its anti-wear property at extreme pressure

Lanthanum trifluoride, a kind of surface-modified micro-powder, was prepared using the reaction of solution and a proper modification technique. With the powder used as an anti-wear additive at extreme-pressure, the value of p_B and diameter (D) of wear scar were established through four-ball experiments, which indicated that lanthanum trifluoride had better anti-wear properties at extreme-pressure and better lubricating ability than ZnDDP (zinc dialkyldithiophophate) readily available on market. The rubbing surface of the balls used for experiments were analysed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) for microstructure and chemical composition. The lanthanum trioxide and iron oxides etc. in the friction surface are main cause for the good anti-wear properties of LaF₃.