Surface Tension, Thermal, and Rheological behaviors of Oleic acid-modified MoS2/Hydraulic oil nanofluids
Résumé
The main challenge for nanofluids (NFs) is achieving and maintaining the long-term stable dispersion of nanoparticles within the hydraulic oil base stock. This study investigates the synthesis, characterization, stability, and performance evaluation of hydraulic oil-based NFs containing oleic acid-modified MoS2 (OA-MoS2) nanoparticles (NPs). Stable NFs were prepared by dispersing OA-MoS2 NPs in ISO 46 hydraulic oil at concentrations of 0.02–0.08 wt%. Comprehensive characterization via XRD, XPS, TGA, BET, SEM, EDX, and zeta potential analysis confirmed successful surface modification, enhanced crystallinity, and excellent colloidal stability. Rheological assessments revealed shear-thinning behavior across all concentrations, with optimal viscosity reduction observed at 0.04 wt%. The viscosity index improved significantly at higher nanoparticle loadings, indicating enhanced thermal stability. Thermal conductivity increased by up to 41.8% at 50°C, while surface tension decreased non-monotonically, with a minimum at 0.06 wt%. Flash point and pour point were enhanced by 4.76% and 20%, respectively. The results demonstrate that OA-modified NFs offer improved thermophysical and rheological properties, making them promising candidates for high-performance hydraulic fluids with superior lubrication, thermal management, and energy efficiency.