Stability of nanosized Fe₃O₄ magnetic fluids

The preparation of Fe₃O₄ nanoparticle with liquid-phase coprecipitation and the dispersion of magnetic particle in water by grinding was introduced, and nanosized Fe₃O₄ magnetic fluids were gained. Nanoparticle was dispersed and surface treated with joining Cetyltrine thylammonium bromide (CTAB), the affect of the factors such as the time of grinding, pH value and dosage of CTAB on stability of nanosized Fe₃O₄ magnetic fluids was studied. The dispersion theory of nanoparticle in water was studied. The result shows that these factors have important impact on stability of Fe₃O₄ nanoparticle magnetic fluids. At acidic condition, dispersion stability of magnetic liquid is the best when the time of grinding is 4-5 h and dosage of CTAB is 8% of dosage of Fe₃O₄ nanoparticle. Surfactant has got up protective action to restrain particle birdnesting, and dispersion to make stability of magnetic liquid better.