The effect of molecular structure of n‐containing heterocyclic compounds on their wear properties

The friction and wear properties of N‐containing heterocyclic compounds (indole, indazole and benzotriazole), which have the same cyclic structure except for the number of N atoms, added to alkylbenzene and to a mixture of liquid paraffin with 2 % wt succinimide dispersant were evaluated using a four‐ball machine. The N‐hexadecanoylindazole and N‐hexadecanoylbenzotriazole were synthesised, and their friction and wear properties in liquid paraffin were also evaluated. X‐ray photoelectron spectroscopy (XPS) was used to examine the binding energy of N_1s on the rubbed surface. The effect of the presence of a lone electron pair of nitrogens in the compounds on antiwear property is discussed using the theory of molecular orbits.