EXPERIMENTS REGARDING THE ROLE OF MAGNETIC/NON-MAGNETIC STIRRING IN THE PROCESS OF FERROPHASE PREPARATION FOR STABLE MAGNETIC FLUIDS Poster

This study is focused on the optimization of oil-based magnetic fluid preparation. Soft magnetic materials in the form of colloidal suspensions of iron oxides have been prepared based on magnetite nanoparticles and hydrocarbons aiming to obtain raw materials suitable for wide range technical uses, as well as for peculiar biological applications. The ferrophase was dispersed in kerosene and sterically stabilized with oleic acid surfactant, magnetic and non magnetic stirring being applied in the frame of several preparation protocols. Small particle size, as well as narrow size distribution represent a “sine qua non” condition of magnetic fluid utilization [1-2]. The stability of magnetic colloidal suspensions is strongly dependent on the solid phase granularity, as summarized by Rosensweig [3]. Stable magnetic suspensions can be produced consisting in magnetite nanoparticles coated with surfactant layer, when the diameter of the ferrophase core is lower than about 10 nm. Several synthesis methods of preparation and stabilization of nanoparticles of appropriate size have been developed, the most classical methods being the co-precipitation of iron salts, and the mechanical grinding of larger, micron sized particles. Size reduction by “wet ” milling allows one to obtain small and rather uniform ferrophase particles [4-6], however the long tim