Effect of molecular structure of organic borates on their friction and wear properties

Six organic borates of different molecular chain length were synthesised, and the friction and wear properties of these borates as oil additives were evaluated using a Timken Tester. X‐ray photoelectron Spectroscopy (XPS) was used to study the surface composition and valence state of boron on the rubbed surfaces. It was found that the antiwear and friction reduction effects of the borates are significantly influenced by the molecular chain length. The longer the chain length, the lower the friction coefficient and wear, and the higher the failure load. XPS analyses of rubbed surfaces revealed that the binding energy of B_IS increased after rubbing, but no pure B(OH)₃ and B₂O₃ was generated. the load‐carrying capacity and the antiwear effect are probably related to the ratio of numbers of carbon atoms to numbers of boron atoms on the rubbed surfaces.