Influence of h-BN and ZnO nanoparticles on the tribological and corrosion performance of non-edible vegetable oils: A Comparative Study

Abstract

This study investigates the tribological and corrosion performance of nanolubricants formulated from Madhuca indica (MI) and Polanga (PO) oils reinforced with hexagonal boron nitride (h-BN) and zinc oxide (ZnO) nanoparticles for sustainable lubrication applications. Friction, wear, and surface characteristics were evaluated using four-ball tribological testing, optical microscopy, scanning electron microscopy (SEM), and three-dimensional surface topography analysis. The addition of nanoparticles reduced friction and wear while improving the surface integrity of the worn specimens compared with the base oils and Belcool EC-50 (BEC). Surface characterization revealed severe wear damage, characterized by pronounced grooves and higher roughness, in the base oils and BEC. BEC exhibited the highest coefficient of friction (0.134) and wear-track roughness (0.4106 μm), indicating severe abrasive–adhesive wear. In contrast, MIZ2 (MI + 0.10 wt.% ZnO) produced shallow and uniform wear grooves characteristic of mild abrasive wear. Among all formulations, POH2 (PO + 0.30 wt.% h-BN) exhibited the smoothest wear track with minimal surface damage, lower friction and wear scar diameter, and approximately 54% lower surface roughness than the corresponding base oil. However, increasing the nanoparticle concentration beyond the optimum level increased wear-track roughness, indicating deterioration in surface quality. The superior performance of POH2 is attributed to the layered structure of h-BN, which provided effective surface protection. Corrosion analysis further confirmed the enhanced corrosion resistance of the developed nanolubricants, highlighting their potential as environmentally sustainable lubricants with improved tribological and surface protection performance.