Experimental Evaluation of the Tribological Properties of CuO Nano-Lubricants at Elevated Temperatures

Abstract

Tribofilms formed from Copper oxide (CuO) nanoparticles in the nano-lubricant under boundary/thin film lubrication conditions have been studied. The tribological performance is linked to the tribofilm properties and consequently to the lubricating conditions. In the present study, analysis of mineral oil (paraffin oil) and vegetable oils (coconut oil and mustard oil) as a nano-lubricant has been carried out in the perspective of its tribological behaviour using a pin-on-disc tribometer. Small quantities of CuO nanoparticles are added to the base lubricating oil and ultrasonic shaking is carried out on the mixture, to formulate the corresponding nano-lubricant. The variation of its friction-reduction and anti-wear properties have been analysed at ambient and elevated temperatures. Viscosity, flash-point and fire-point of the base lubricants and the nano-lubricants have been measured. From the dispersion analysis it is seen that the nano-lubricant is not suitable enough for long stationary applications. Surface structure of the worn surfaces obtained by Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) shows that the average roughness value decreases drastically when nano-lubricants are used rather than the base lubricants. With the current interest in lubricants from renewable sources, studies on vegetable oil based nano-lubricants and means of predicting their performance are given predominance in this work.