Regulating performance characteristics of lithium complex greases via dibasic acids

Abstract Thickener as an important ingredient affects the performance characteristics of lubricating grease. Here, seven lithium complex greases (LCGs) were prepared by saponification of 12‐OH stearic acid and low molecular weight dibasic acids (including adipic acid, sebacic acid, phthalic acid, dodecanedioic acid, and the combination of sebacic acid and phthalic acid in different molar ratios) with LiOH, using polyalphaolefin (PAO 40) as base oil. Physical properties and lubrication function of as‐prepared LCGs were evaluated in detail, and the friction mechanism was explored via analysis on the morphologies and composition of worn surfaces. Results illustrate that the saponification of mixed 12‐OH stearic acid and sebacic acid with LiOH provides good thickener for improving the physico‐chemical performance of LCG, while the thickener prepared by 12‐OH stearic acid and adipic acid with LiOH enhances lubrication function of LCG, mainly depending on synergy of grease film and tribo‐chemical reaction film.