Abstract: The main components of leaf-surface waxes are hydrocarbons, alcohols, acids and esters, among which hydrocarbons account for about 50%. The leaf-surface waxes of Populusnigra and Robiniapseudoacacia cv. Idaho were extracted and used as grease additives, and the resulting grease was compared with the pure alkanes added in the grease. A MTF-R4000 reciprocating friction and wear tester was used to investigate the effect of wax additives on the tribological properties of lithium complex grease. An optical microscope and an energy dispersive spectroscopy (EDS) were employed respectively to observe the surface morphology of the wear scars and analyze the elements on the surface of wear scars. The results showed that the leaf-surface wax can improve the friction reduction and anti-wear capacities of the lubricating grease more effectively than the pure alkanes. This attributed to the combined action of hydrocarbons, alcohols, esters and other components in the wax, forming an effective protective film through adsorption and chemical reaction, leading to the improved tribological properties.

Key words: plant leaf-surface wax, environment-friendly, tribological property, grease