Green synthesis and tribological behaviors of three novel benzothiazole-derived borate esters as lubricant additives in mineral oil

Abstract

Three ashless and nonphosphorus benzothiazole-derived borate esters were synthesized by a halide-free green synthesis method. The results show that the hydrolytic stability and tribological characteristics have been significantly improved. Scanning electron microscopy was used to analyze the morphologies of the rubbing surfaces. X-ray absorption near edge structure spectroscopy was also adopted to investigate the thermal films and tribofilms of the synthesized additives. The analysis results indicate that the thermal films are mainly composed of FeSO4 and B2O3, while the tribofilms consist of the components of FeS, FeSO4, and B2O3.