EFFECT OF CONCENTRATION OF MAGNETIC PARTICLES ON FERROOIL’S DYNAMIC VISCOSITY AS A FUNCTION OF TEMPERATURE AND SHEAR RATE

Abstract

Ferrooil’s dynamic viscosity changes significantly alter the tribological properties and thus its usefulness as a lubricant of the sliding journal bearings. Due to the fact that the ferrooil demonstrate strong magnetic polarity in the presence of an external magnetic field, it is possible to control the viscosity by means of an external magnetic field just by changing the intensity as well as by changing of the concentration of magnetic particles. There is presented an effect of the changes of the concentration of magnetic particles included in the ferrooil on the dynamic viscosity in the absence of external magnetic field in this paper. The study was conducted in the context of temperature’s and shear rate’s changes. In that way, it was also taken into account the influence of external physical conditions of ferrooil’s employment. Tests were performed on HAAKE MARS III rheometer for the shear rate range from 0 to 100000 1/s and temperature of work to 120oC and the tested ferrofluid was product of FerroTec of Unterensingen (Germany), which is a mixture of colloidal mineral motor oil Penzzoil’s LongLife Gold's SAE 15W-40 with Fe 3O4 magnetic particles at a concentrations of: 8, 6, 4, 3, 2 and 1% and the surfactant. Addition of surfactant is to prevent clustering of magnetic particles in the oil. The paper presents, in the form of graphs, the changes of ferrooil’s dynamic viscosity as a function of temperature, shear rate and concentration of magnetic particles. The results of research were also subjected to analysis. This work is part of a wider study on the analysis of changes in operating parameters of journal bearing ferrofluid’s lubricated.