Enhancing the Performance of Rapeseed Oil Lubricant for Machinery Component Applications through Hybrid Blends of Nanoadditives

Bio-lubricants have demonstrated promising tribological and physical properties, suggesting their potential advantages in the lubrication of critical machinery components. This study investigates the impact of using blended individual and hybrid nanoadditives, such as graphene nanoplatelets, ZnO, and an ionic liquid (IL) of Trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl)phosphinate, on the rheological, tribological, and physical characteristics of rapeseed oil. A commercial cutting fluid (BLASER Vasco 6000) (VB 6000) is used for comparison. The results revealed a substantial improvement in viscosity index (VI) values for mixtures containing graphene nanoplatelets, reaching up to 150%, as compared to VB 6000. Regarding the tribological behavior, the friction coefficient achieved a reduction of up to 20% at room temperature (RT) and 26% at 60 °C for the hybrid containing all three nanoadditives (H3), outperforming the commercial fluid. Moreover, H3 demonstrated the most substantial reductions in wear volume (84%) and surface roughness (60%). The wettability of H3 benefited from the combined mechanisms of the applied nanoadditives; its application the contact angle decreased by 63%, revealing its outstanding spreadability. The results reveal the high potential of the H3 hybrid as a competitive and green metal working fluid that can replace hostile and toxic ones in industrial applications.