Tribological study of boron-containing soybean lecithin as environmentally friendly lubricant additive in synthetic base fluids

Environmentally friendly boron-containing soybean lecithin (BSL) was synthesised. Constant temperature and humidity box was applied to evaluate the hydrolytic stability of the novel lubricant additive. The friction-reducing, anti-wear, and extreme pressure performance of BSL in synthetic base fluids were studied by an optimol SRV-I oscillating reciprocating friction and wear tester and four-ball tester. The hydrolytic resistance test results reveal that BSL possesses good hydrolytic stability. Tribological tests show that the friction-reducing performance of BSL in A51 is inferior to PAO10. The incorporation of BSL in synthetic basestock can dramatically reduce the wear volume of the lower steel disc under different test conditions. BSL can also enhance the load-carrying capacities of the synthetic base fluids. Morphology and chemical composition of the wear surface were characterized by scanning electron microscope and X-ray photoelectron spectroscopy. The results indicated that excellent tribological performance of the BSL can be attribute to the formation of chemisorption and chemical reaction protecting films composed of Fe ₂O ₃, iron polyphosphates, organic amines, and BN, etc.