Experimental study of the surface tension of a magnetic fluid and its liquid base

Abstract

The action of an external magnetic field on a magnetic fluid surface tension is a topical problem that has been repeatedly addressed theoretically, with a relatively small number of experimental studies conducted. The purpose of our work is systematic experimental research on the surface tension of a magnetic fluid and its non-magnetic liquid base by static and dynamic methods. We carried out a detailed study of the physicochemical properties of a decane-based magnetic fluid with magnetite particles stabilized by oleic acid. The dependences of the surface tension and viscosity of the non-magnetic liquid base on the concentration of the stabilizing liquid in it and temperature were systematically studied. A modified capillary waves method (CWM) was used to measure the surface tension; the results were verified with data obtained using a high-precision commercial tensiometric device. It is shown that with an increase in the concentration of oleic acid in decane, the surface tension of the solution increases. With an increase in the external vertical magnetic field strength, the surface tension of the decane-based magnetic fluid decreases, which is consistent with theoretical results of other authors. The obtained results confirm the hypothesis about the physical mechanism of the change in the surface tension of a magnetic fluid in a magnetic field due to the redistribution of magnetic particles in the near-surface layer.