Synthesis and Tribological Analysis of CuO and TiO2 Nanoparticles based Bio-lubricants

Abstract

Purpose. Depleting reserves of crude oils and their adverse environmental effects have shifted focus towards environment friendly and biobased lubricant base oils. Natural oils and fats act as good lubricants but they have low oxidation and thermal stability, along with poor tribological characteristics, which makes them unsuitable to be used in engine components. Chemical modifications of the natural oils, especially esterification with Trimethylolpropane (TMP) and use of nanoparticles show much promise. Methodology. In this work, cottonseed oil (CSO), waste cooking oil (WCO) and Ratnajot Oil (RJO) are converted to TMP lubricant by a two-step based catalyzed esterification. Nanoparticles of CuO and TiO2 are added to chemically modified lubricants at a concertation of 1% by weight. Phycisochemical properties of the lubricants are analyzed and then lubricants are tested for Tribological characteristics Findings. Both the nanoparticles resulted in a decrease in the viscosity index of biolubricants of CSO, RJO and WCO. Addition of nanoparticles have significantly improved the flash point temperatures of all the lubricant samples. TiO2 nanoparticles resulted in reduction in average COF, while the WSD was increased for all the biolubricants containing TiO2 nanoparticles. Value. Chemically modified bio-lubircants with nanoparticles can be used as commercial lubricants to improve oil deterioration characteristics and environmental impact. However, further work on improving bio-lubricant’s wear characteristics is needed for complete replacement of mineral oil based lubricants.