Enhancing the dynamic thermal stability of metal oxide oil-based nanofluids through synchronous chemical modification and physical coating

The stability of oil-based nanofluid, especially dynamic thermal stability, hinders its practical application in industries. To enhance the stability of oil-based nanofluids, an excess amount of hexadecyl trimethoxysilane was employed to synchronously achieve chemical surface modification and physical coating of metal oxide nanoparticles. This process can efficiently render the nanoparticle surface lipophilic while introducing steric hindrance. The dynamic thermal stability and long-term durability of the nanofluids were confirmed through extended resting and thermal cycling experiments. Additionally, various characterization methods were employed to examine certain properties of the modified nanoparticles. The results reveal that the modified nanoparticles exhibit lipophilic characteristics, effective dispersion, and robust thermal stability. The nanofluids prepared using these modified nanoparticles remained stable for 3 months during resting periods and withstood 21 days of thermal cycling at 130 °C. This positions them as promising heat transfer mediums for mid-temperature industries. Importantly, this stabilization technique exhibits potential applicability across a wide range of hydrophilic metal oxide oil nanofluids, as suggested by mechanistic analysis. The exploration of dynamic thermal stability mechanisms is of great practical significance in promoting the large-scale application of nanofluids in industry and provides insights that could potentially resolve the longstanding challenge of nanofluid stability.