STUDY ON TRIBOLOGICAL PROPERTIES OF THE COMPLEX OF RARE-EARTH DIALKYLDITHIOCARBAMATE AND PHENANTHROLINE IN LUBRICATING GREASE

Three complexes of rare earth dialkyldithiocarbamate (DTC) and phenant hroline (Phen) were synthesized. Their tribological properties as addi tives in lithium grease were evaluated using a four-ball machine and a SRV machine. As a comparison, the tribological properties of molybden um dialkyldithiocarbamate (MoDTC) as an additive in lithium grease wer e also investigated. The thermal stabilities of rare earth complexes w ere also investigated with a thermal gravity analyzer. The results ind icate that these rare earth complexes possess excellent load-carrying capacity, antiwear and friction reduction properties, and high thermal stability. Their extreme pressure properties are superior to that of MoDTC. At lower concentration and lower load, the antiwear properties of lanthanum and neodymium complexes are superior to those of MoDTC. A t lower concentration and higher load, the antiwear properties of the these rare earth complexes are inferior to those of MoDTC. But the wea r increases, as the increase of concentration of rare earth complex. T he results of Auger electron spectroscopy and X-ray photoelectron spec troscopy analyses indicate that these rare earth complexes as additive s in lithium grease can form a protective him containing rare earth ox ide, sulfate and an organic compound containing sulphur and nitrogen o n a rubbed surface. Especially, the lubricating film rich in rare eart h and sulphur contributed largely to the excellent tribological proper ties of EDTC . Ln . Phen.