Leaf-surface wax of desert plants as a potential lubricant additive

Using an MFT-R4000 tester at room temperature, the leaf-surface wax of two desert plants, Ammopiptanthus mongolicus (AM) and Reaumuria soongorica (RS), was extracted and evaluated for its potential as a lubricant additive in polyalphaolefin (PAO) for steel-steel contact. Gas chromatography-mass spectrometry analysis was performed to identify the composition of the AM leaf-surface wax, and scanning electron microscopy and X-ray photoelectron spectroscopy were used to investigate its friction mechanisms. The results suggest that the leaf-surface wax could successfully reduce the friction and wear of steel-steel sliding pairs compared with PAO containing molybdenum dithiocarbamate additives. AM, in particular, showed high-performance wear resistance and friction-reducing properties. Its excellent tribological properties were attributed to the wax composition of leaf-surface fatty acids, alcohol, and esters.