| To explore practical application of thermal nanofluids,the dispersion stability is very important to maintain physical and chemical properties of nanofluids.However,it’s challenging to prepare stable nanofluids,especially for silicone oil based nanofluids that are used at relatively high operation temperatures.In the work we report a reliable and effective strategy to prepare stably dispersed silicone oil based nanofluids that enable the high temperature operation.The strategy involves a series of process including controlled high-temperature synthesis of nanoparticles by solvothermal synthesis,stabilizer design and synthesis,surface modification of particles,and post-modification particle size partition.The solvothermally synthesized particles not only possess high thermal stability,but also provide facilities for easy surface modification through ligand exchange.The phosphate-terminated polydimethylsiloxane ligands that simultaneously possess high compatibility with the silicone oil base fluid and high-temperature stability were used to exchange synthetic ligands and robustly anchor onto the particle surfaces offering effective screening of the inter-particle attraction.After centrifugation treatment to remove the large-sized surface-modified particles,the prepared nanofluids have demonstrated stable dispersion at temperatures slightly lower than the particle synthesis temperature.The stably dispersed Fe3O4/silicone oil nanofluids have been successfully utilized for consistent volumetric harvest of solar thermal energy at more than 110℃. |
