The effect of chemical structure on the load-carrying properties of amine phosphates

Abstract The load-carrying properties of a range of dialkyl phosphates and their alkylamine salts were assessed using the four-ball machine. The antiwear and extreme-pressure properties of these additives were found to be markedly dependent on the structure of both the acid phosphate and the amine. Similar trends were not observed for the dithiophosphate analogues. Possible explanations for these results are presented.