Tribological behaviors of novel tri(hydroxymethyl)propane esters containing boron and nitrogen as lubricant additives in rapeseed oil

The purpose of this paper is to study the tribological performance of tri(hydroxymethyl)propane esters containing boron and nitrogen as lubricant additives in rapeseed oil. Thermal degradation tests were performed to analyze their thermal stability using a thermo-gravimetric analyzer. Two four-ball testers were used to measure the tribological properties of tri(hydroxymethyl)propane esters containing boron and nitrogen as lubricant additives in rapeseed oil. The worn surfaces of steel balls were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The results show that the tri(hydroxymethyl)propane esters containing boron and nitrogen have excellent thermal stability, good antiwear performance, improve the load-carrying capacity, and possess friction-reducing behavior especially at 98 N when they are used as additives in rapeseed oil. The results of XPS show that the adsorption and tribochemical reactions have been occurred to form a complex boundary lubrication film. The paper illustrates two novel tri(hydroxymethyl)propane esters which contain B and N elements used as additives in rapeseed oil. The results are useful for further applications in advanced environment friendly lubricating oils and additives.