Thermophysical and stability analysis of rapeseed oil-based nanofluids

For sustainable manufacturing, attempts are being made to replace the mineral-based harmful coolant with biodegradable cutting fluids. Vegetable oil-based nanofluids (NFs) provide a cost-effective solution for this problem. Therefore, in this study, rapeseed oil-based mono and hybrid NFs were prepared at nanoparticle concentrations of 1.0 and 1.5 vol% and were further characterized to evaluate their suitability as cutting fluid. NFs were characterized by UV-vis spectroscopy and Zeta Potential (ZP) analysis. Furthermore, thermal conductivity, density, viscosity, contact angle, TGA-DSC, and surface tension were also investigated. ZP value decreases as the concentration of NPs increases, and all samples fall within the stability range criteria. It was observed that heat transfer capacity enhanced by 2.17% for MNF and 2.54% for HNF at 1.5 vol% compared to 1.0 vol% at 50 °C. The density and viscosity of both MNF and HNF increase with NP concentration, but values of density decrease as the temperature of NF increases from 30 °C to 75 °C. At 1 vol%, the contact angle obtained for all samples is less than 90°, representing better wettability and lubricity of prepared NF than 1.5 vol% concentration. Due to the high intermolecular repulsive forces within particles at high concentrations, a low surface tension value is obtained. The additives increase thermal stability, as seen in TGA analysis, while the DSC technique helps in investigating the initial reaction temperature based on heat flow. The findings were compared with those of the previously published paper by authors containing DI water as BF.