Tribological properties of P- and N-containing organic compounds as potential extreme-pressure and antiwear additives

An amine salt of an alkoxylphosphate fa P- and N-containing organic compound, PN) was synthesised. Its extreme-pressure, antiwear, and friction-reducing properties were evaluated as an additive in liquid paraffin and a mineral oil. Tests were performed on a four-ball friction and wear tester with an AJSI 52100 steel ball self-mated pair and the results were compared with those of sulphurised olefin (SOj, zinc di-n-butyldithiophosphate (ZDDP), and dibutyiphosphite (DBF). The morphologies of the worn steel surfaces were observed using a scanning electron microscope, while the binding energies of some typical elements on the worn surfaces were determined using X-ray photoelectron spectroscopy. The additives were found to increase the load-carrying capacity and to reduce wear and friction coefficient considerably. PN as an additive exhibits better load-carrying, antiwear, and friction-reducing properties than SO, ZDDP, and DBP under the same test conditions.