Preparation Of Nano-fe 3 O 4 Particles Induced By Weak Exterior Magnetic Fieldand Magnetic Fluid Stability Study

Magnetic fluid was a colloidal system with magnetic nano-particles dispersed in the stable liquid phase. It combined the magnetism of the solid with the fluidity of the liquid, showing a magnetic, optical and other special phenomenon. Magnetic fluid was widely used in the aerospace, electronics, chemicals, machinery, energy, metallurgy, environmental protection, bio-medical and other fields. The preparation of magnetic fluid was a complex technological process, requiring the magnetic fluid in the rheological property to be controlled, stable and reliable. Therefore, the process involved to the magnetic particle gain, the surface active agent and the determination of the base fluid, the method and so on. This paper focused on the appropriate method of magnetic nano-particles preparation, maintaining the dispersion of magnetic particles and magnetic fluid stability.In this paper, a specific morphology of Fe3O4 nano-particles was firstly prepared by oxidation of the co-precipitation method under the weak magnetic field. The results showed that the size distribution of Fe3O4 magnetic particles became narrow, the average particle size and crystal size became larger. And the weak magnetic field could induceα-FeOOH to transform to be Fe3O4 accelerately. There was also a secondary nucleation and the morphology of secondary growth synthesis in the production of Fe3O4 nano-particles.Secondly, silane coupling agent KH560 was used as a surfactant of Fe3O4 magnetic fluid; in order to obtain better stability of magnetic fluid, this paper added a secondary dispersant Span80 to enhance stability. Through comparative experiments, the optimal amount of KH560 and Span80 were determined. Experimental results showed that the magnetic fluid in the 20# engine oil has a better dispersion, when the KH560 concentration was 1.5% and secondary dispersant Span80 was 3% by the reaction of initial surface modification.Finally, this paper provided a method of the magnetic fluid preparation when nano-Fe3O4 magnetic particles as a carrier, silane coupling agent KH560 as surfactant and Span80 as Secondary dispersing agent in the 20# oil-based fluid. The method of preparation improved the effect of stability; and the way is simple, operable, low cost and high efficiency.