关键词: 成膜能力, 硅油, 离子液体, 润滑失效

Abstract: Ionic liquids now receive increasing attention in the mechanical lubrication research area. However, the film forming properties of ionic liquids are still rarely discussed. The film forming properties of several common phosphate ionic liquids with different side chain lengths of the cation are investigated under different pressures. Also, the lubrication failure and compression resistance of these ionic liquids are discussed by taking silicon oils with similar viscosities as comparative objects. The results show that the lubrication behaviors of these ionic liquids accord with the elastohydrodynamic lubrication (EHL) theory at high entraining speed and they accord with the thin film lubrication (TFL) theory at low entraining speed. With the increase of the side chain length of the cation, the difference between the measured central film thickness in the contact region and the calculated value according to the EHL theory tends to reduce in the TFL regime. It is primarily due to the decrease in the number of ions per unit volume and the effect of steric hindrance. When the entraining speed decreases to about 0.1 mm•s, no obvious lubrication failure point is observed for the tested ionic liquids. The ionic liquids possess better compression resistance than silicon oils with similar viscosities as a result of the strong electrostatic interaction between ions and charged solid surfaces.

Key words: Film forming characteristics, Ionic liquids, Lubrication failure, Silicon oil