Preparation and Tribological Properties of Lanthanumdoped Muscovite Composite Particles as Lubricant Additives in Lithium Grease

Lanthanum-doped muscovite (MC) composite particles (hereinafter abbreviated as La-MC) were prepared by the mechanical solid-state-chemistry-reaction method, followed by surface modification with oleic acid. The microstructure of materials was characterized by SEM, XRD, EDS and FTIR. Furthermore, the friction-reduction and anti-wear properties of MC and La-MC as lubricant additives in lithium grease were evaluated using a four-ball friction and wear tester. The results showed that La(OH)3 nanoparticles were coated on the surface of muscovite. Both MC and La-MC can effectively improve the friction-reduction and anti-wear properties of lithium grease and La-MC presents better tribological propertiesthan MC. The excellent tribological properties of La-MC can be attributed to the formation of the adsorbed La-MC film and the chemical reaction film mainly composed of Fe2O3 and SiO2 on the worn surface, as well as the catalysis of lanthanum element during the friction process.