Study On The Properties And Lubrication Mechanism Of Blends Of Poly Alpha-olefins With Synthetic Esters

Synthetic oils is one kind of lubricating oil which not only have much better properties than mineral oils, but also can save oil resources and reduce environmental pollutions. So synthetic oils have been more and more widely used in the word. Poly alpha-olefins (PAOs) and synthetic esters, which are two main kinds of synthetic oils, have their own advantages and disadvantages. Blednding gets a better way to achieve better properties and reduce cost.In this work, the properties of blends of PAOs with synthetic esters have been systematically investigated, and the lubrication mechanism of blends of PAOs with neopentyl polyol esters have also been explored by SEM, LSCM and XPS. The following conclusions can be drawn:1. Blending PAOs with synthetic esters can get an optimum balance of the physico-chemical properties of the two kinds of lubricating base oils.2. For monoester, aromatic ester and neopentyl polyol esters, they all show a synergistic boundary lubrication effect with similar viscous PAOs. So the blends under a certain proportion can take place of synthetic esters to reduce cost. PAO4-neopentyl glycol dioleate blends show the best synergistic boundary lubrication effect. When the concentration of neopentyl glycol dioleate are 20% and 40%, the wear scar diameters of the blends are reduced by 18.2% and 14.5% as compared with that of neopentyl glycol dioleate respectively, which indicated the blends have better antiwear properties; When the concentration of neopentyl glycol dioleate are 60% and 80%, the PB values of the blends are increased by 4.6% and 7.7% as compared with that of neopentyl glycol dioleate respectively, which indicated the blends have better extreme pressure properties.3. The film-forming properties of blends confirm that blended oils in which the major component has relatively low polarity and viscosity show better tribological properties.4. The results of surface analysis reveal that the chemical adsorption films and chemical reaction films serve as a protective layer between the frietional pairs under the lubrication of blends of PAOs with neopentyl polyol esters. The chemical reaction films are composed of Fe3O4, FeO, FeO3 and [Fe(CH3C(O)CHC(O)CH3)3]. Moreover, PAOs and neopentyl polyol esters get a synergistic boundary lubrication effect under both AW and EP conditions.