Enhancing the tribological properties of hydraulic oil-based nanolubricants using MWCNT-SiO2 hybrid nanoparticles

Hydraulic oils used in heavy machinery are designed to provide lubrication and anti-wear properties under extreme load conditions. In the present study, thermophysical and tribological properties of industrial-grade hydraulic oil (SAE68) with hybrid nanoparticle (MWCNT/SiO2) additives have been experimentally evaluated. Field Emission Scanning Electron Microscopy (FESEM) revealed that MWCNT and SiO2 nanoparticles are having tubular and spherical morphology, respectively. UV-Spectroscopy test reflects the stability of prepared hybrid nano lubricants with moderate agglomerations of nanoparticles dispersed into base oil. The viscosities of nano lubricants were determined varying both the nanoparticle volume fraction and temperature. Anti-friction and anti-wear properties of nano lubricants are inspected using a Four-ball tribotester apparatus according to ASTM D4172 standard. The hydraulic oil containing an optimum volume fraction of 1.8% MWCNT/SiO2 nanomaterials at a ratio of 20:80 reveals a remarkable reduction in coefficient of friction and wear scar diameter by 92.99% and 14% respectively compared to pure oil. The morphology and chemical compositions of worn steel ball surfaces are examined by FESEM and Energy-Dispersive Spectroscopy (EDS) for both base oil and nano lubricant samples. It is also evident from the present tribological investigation that the combination of ball bearing effect and mending effect mechanism improves the friction and wear properties for hybrid nano lubricants which will certainly enhance the performance of machine components.