In this study, perfluoropolyether oil-based ferrofluid was prepared to satisfy special demands in applications which are too harsh to conventional ferrofluids. Fe3O4 magnetic nanoparticles were synthesized by co-precipitation and modified by perfluoropolyether carboxylic acid surfactant in the atmosphere without protective gas. Perfluoropolyether oil-based ferrofluid was prepared with modified nanoparticles and perfluoropolyether by high-energy ball milling. Properties of ferrofluid fabricated were verified through a series of experiments. Ferrofluid stability was tested by interval point-density method; the average density change is merely 0.0077 g/ml, and change rate is 0.37% after 500 days. Saturation magnetization is 582.46 Gs, much larger than the other four ferrofluids. The average volatility rate is 7.4985*10− 5 g/h/cm2 at 80 °C after 260 h. Viscosity increases to 1825.7 mPa⋅ s under − 20 °C and still have mobility at − 40 °C. The ferrofluid can resist air blast for 8 h under 200 °C without oxidation or decomposition. Perfluoropolyether oil-based ferrofluid cannot be damaged by water or organic solvents. In addition, the ferrofluid can survive in pH = 1 acid or pH = 14 alkali at least 279 days without corrosion.
Read full abstract