Study On Preparation Process Of Nano-LaF₃ Lubricant Additives

Due to its special physical and chemical properties, rare earth materials have been paid great attention to, its tribological properties research has also caused people's great interest. The process that oil-soluble LaF3 nano-particles were prepared in alcohol-water system was studied in this paper. Effects of the molar ratio of the surface modification agent and LaF3, the volume ratio of alcohol and water, the molecular structure of alcohol, the surface modifier structure on synthesized additives, were investigated. At the same time, the tribological properties were investigated by a four ball machine.Experimental results showed that:the average size of nanoparticles which were prepared in ethanol-water solution was about 10nm, with no obvious aggregation phenomenon. When the preparation condtions are as follows:the reaction media being ethanol-water solution, the volume ratio of ethanol and water being 3:1, the molar ratio of the surface modification agent and LaF3 being 2:1, the nano-particles prepared as lubricant additives have the best performances, such as, dispersion stability, high-temperature stability and tribological properties. The surface modifiers used in the experiment were respectively DDPPY, DDPDA, DDPT152, DDPE18A and OAE18A. The tribological performance of the oil sample containing surface modification LaF3 nano-particles was significantly better than the sample containing surface modifier only. Among the used surface modifiers, the tribological performance of the additive containing LaF3 nano-particles modified by DDPT152 was best, and PB value of the additive containing LaF3 nano-particles modified by OAE18A was the minimum, The surface modifier with long alkyl chains and sulphur phosphorous hetero atoms could increase the tribological performance of the additive containing LaF3 nano-particles.