In this study, we synthesized two types of calcium sulfonate complex greases (barium soap and\ncalcium soap) and investigated their physical, rheological, and tribological properties in detail. The test results\nshowed that the evolution of their linear viscoelasticity functions with frequency were quite similar to those of\ntraditional lubricating greases. Moreover, these two calcium sulfonate complex greases had good friction reducing\nand antiwear properties at room temperature and at 150 �°C. In addition, by adding an organic\nmolybdenum compound (MoDTC) to the base greases, we obtained a very low friction coefficient (0.065) for\none of the greases (calcium soap) at 400 N and 500 N (maximum Hertzian pressures of 3.47 GPa and 3.74 GPa,\nrespectively) at 150 �°C. X-ray photoelectron spectroscopy (XPS) analysis showed that the tribofilm was composed\nof some complex oxide species and CaCO3 that had formed on the worn surface.
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