Probing the Synergy of Blended Lithium Complex Soap and Calcium Sulfonate Towards Good Lubrication and Anti-Corrosion Performance

Thickener plays a significant role on the performance of grease, including rheological property, chemical and thermal stability, colloidal and mechanical stability, and so forth. Here, lithium complex-calcium sulfonate (L/C) greases were synthesized via regulating lithium complex soap and calcium sulfonate in the molar ratio of 1:2, 2:1 and 1:1, along with thickening the polyalphaolefin (PAO40). The physicochemical properties, corrosion resistance and tribological performance were evaluated in detail, with lithium complex grease and calcium sulfonate grease as a comparison. The results show that the as-prepared L/C greases have good corrosion resistance for low-carbon steel due to unique reversed micelles of calcium sulfonate and sealing function. The regulation of lithium complex soap and calcium sulfonate in different molar ratios achieves the considerable adjustability of grease’s physicochemical and tribological properties due to the component/structure of thickener and its sensitivity to base oil. The grease with formulation of L/C = 1:2 gives the best lubrication function depending on not only the thickener’s component and structure, but also the synergistic lubrication of grease-film and tribo-chemical reaction film composed of Fe₂O₃, FeO(OH), CaO, CaCO₃ and LiOH.