TO EVALUATION TEST OF QUALITY OF MAGNETIC FLUIDS FOR MAGNETOFLUID DEVICES

Magnetic fluid is a colloid of magnetic nanoparticles. Using of magnetic fluids in technical devices demands applying of strong non-uniform magnetic fields for a long time. One of the most widespread magnetic fluid devices are magnetic fluid seals of mobile shafts, magnetic fluid supports, bearings, acceleration and angle of inclination gauges, devices for information input in the computer and etc. These devices demand high quality of used fluids. Processes of magnetophoresis and Brownian diffusion in magnetic fluid lead to concentration of magnetic particles in the areas with higher intensity of magnetic field and increase of fluid magnetization in these areas. A local change of particles concentration in the fluid leads to variation of its physical properties. Formation of aggregates from the particles and the further stratification of magnetic fluid, up to its destruction, may be the most serious consequence of redistribution of concentration of magnetic particles. These factors lead to variation of parameters of magnetic fluid devices; cause disturbance of their normal operation and even failure. Therefore, the consistent, high quality magnetic fluids which are not subject to fast stratification in a non-uniform magnetic field are necessary for effective work of the devices. The procedure of evaluation test of quality of magnetic fluids is proposed in this paper. The test is based on studying of influence of processes of magnetophoresis and Brownian diffusion of magnetic particles in magnetic fluid on the forces acting on the volume of fluid in an external non-uniform magnetic field. The procedure is developed on the basis of analysis of magnetic force variation in time under the action of non-uniform field of permanent magnets. Methods of determination of stability of magnetic fluid, known at present, demand rather complicated equipment and laborious and complex investigations. Proposed procedure can be used as an express method for evaluation of magnetic fluid quality for usage in technical devices, and it does not need complicated equipment.

1. Berkovsky B., Bashtovoi V. (Ed.) (1996) Magnetic Fluids and Applications Handbook. New York, Begell House Inc. Publishers. 851.

2. Rosensweig R. E. (1985) Ferrohydrodynamics. USA: Cambridge University Press. 344.

3. Berkovsky B. M., Medvedev V. F., Krakov M. S. (1989) Magnetic Fluids. Moscow, Chemistry. 240 (in Russian).

4. Suprun A., Romanov Yu., Simonenko D. (2001) Device for Inputting Information into the Computer. Patent No 2168201 Russian Federation (in Russian).

5. Landau L. D., Lifshitz E. M. (1986) Theoretical Physics. Vol. VI: Gidrodinamika. Moscow, Science. 736 (in Russian).

6. Bashtovoi V. G., Berkovsky B. M., Vislovich A. N. (1985) Introduction to Thermomechanics Magnetic Fluids. Moscow: IVTAN USSR. 188 (in Russian).

7. Kaiser R., Miskolczy G. (1970) Magnetic Properties of Stable Dispersions of Subdomain Magnetite Particles. Journal of Applied Physics, 41 (3), 1064–1072. DOI: 10.1063/1.1658812.

8. Mikhalev Y. O., Evsin S. I. (1991) Diagnostic Methods of Magnetic Fluids for Sealing Devices.Magnetohydrodynamics, 27 (1), 29–35.

9. Mikhalev Y. O., Novikov S. I., Orlov D. V., Trofimenko M. I. (1982) The Process of Determining the Stability of Magnetic Colloids. Copyright Certificate USSR No 922586.

10. Bashtovoi V. G., Polevikov V. K., Suprun A. E., Stroots A. V., Beresnev S. A. (2007). Influence of Brownian Diffusion on the Statics of Magnetic Fluid. Magnetohydrodynamics, 43 (1), 17–25.

11. Bashtovoi V. G., Reks F. G., Klimovich S. V. (2014) Experimental Research of Magnetophoresis and Brownian Diffusion Influence on “Magnetic Weight” of Magnetic Fluid. Energetika. Izvestiya Vysshikh Uchebnykh Zavedenii i Energeticheskikh Obedinenii SNG [Energetika. Proceedings of CIS Higher Education Institutions and Power Engineering Associations], (1), 65–69 (in Russian).