Tribological and rheological performance of lithium grease with poly-α-olefin and alkyl-tetralin as base oils

A new category of lithium greases was synthesized by using poly-α-olefin (PAO8) and alkyl-tetralin as base oil, where the alkyl-tetralins were synthesized by the alkylation of tetralin and olefins. The influence of thickener concentration, alkyl-tetralin content and type of blend oils on the rheological and tribological performance of lithium grease was investigated. The microstructures of soap fibers were measured to reveal the structure–property correlations. The concentration of thickener and alkyl-tetralin content obviously affect the lubricating performance of lithium grease, while the molecular structure of alkyl-tetralin has no obvious impact on their properties. It was found that alkyl-tetralin could significantly enhance the thickening ability of PAO8 base oils, and decrease the amount of thickeners by 1.5% (mass). Lithium greases prepared using 20% (mass) alkyl-tetralin as co-base oil exhibited high colloidal stability, excellent rheological behaviors and tribological properties.