Experimental investigation on the thermo-physical properties and tribological performance of acidic functionalized graphene dispersed VG-68 hydraulic oil-based nanolubricant

• Published in: Diamond and related materials 2023-03, Vol.133, p.109740, Article 109740
• Main Authors: Kader, Arsath, Selvaraj, Vishnuprasad, Ramasamy, Palani, Senthilkumar, Karthick
• Format: Article
• Language: English
• Subjects: Acidic functionalization; Graphene; Nanolubricant; Thermal conductivity; Tribology; Viscosity index
• ISSN: 0925-9635; 1879-0062
• DOI: 10.1016/j.diamond.2023.109740

The present work investigates the thermo-physical and tribological properties of acidic functionalized graphene dispersed viscosity grade-68 (VG-68) hydraulic oil nanolubricant and their potential of reducing friction in a mechanical system. The prepared nanolubricant possesses a zeta potential value of −48 mV at pH 7 which shows its high dispersion stability. The thermal conductivity and viscosity index of the nanolubricant enhances with an increase in nanoparticle concentration. A maximum of 67.4 % enhancement in thermal conductivity was observed for 0.4 wt% nanolubricant compared to the base lubricating oil. The viscosity index of 0.4 wt% nanolubricant was enhanced about 2.2 times of the base lubricant. The tribological properties of the nanolubricants were measured using a rotating disc tribometer with an attachment to measure the coefficient of friction. The nanolubricant (0.4 wt%) reduces the frictional coefficient by a maximum of 21.8 % compared to pure hydraulic oil. The wear rate of the rotating disc also decreases with an increase in the nanoparticle concentration in hydraulic oil. A maximum decrease of 35.51 % in wear rate was observed by using 0.4 wt% nanolubricant compared to pure hydraulic oil. The acidic functionalized graphene nanoparticles were identified as a potential additive to protect surfaces against wear by reducing the frictional coefficient and enhancing the load-carrying capability of the lubricant. [Display omitted] •Acidic functionalized graphene dispersed hydraulic oil based nanolubricant was prepared.•Nanolubricant exhibits good dispersion stability and enhanced thermal properties.•Viscosity index and lubricity of nanolubricant enhances with the addition of functionalized graphene.•Significant decrease in the frictional coefficient shows its ability to protect surfaces against wear.