Tribological properties and action mechanism of N,N-dialkyl dithiocarbamate-derived S-hydroxyethyl borate esters as additives in rapeseed oil

Four N,N-dialkyl dithiocarbamate-derived S-hydroxyethyl borates with different carbon chains were synthesized and characterized. Their tribological performances as additives in rapeseed oil (RO) were investigated using two four-ball test machines. It was found that they can greatly improve the extreme pressure and antiwear properties of RO when they are used as additives in RO. The elemental composition and chemical nature of the antiwear film generated on the surfaces of the steel balls were studied with X-ray photoelectron spectroscopy (XPS) and their antiwear mechanism was put forward.