This paper was concerned with theoretical analysis and the static characteristics of the journal bearing lubricated with magnetic fluid. A general Reynolds equation based on magnetic fluid model is obtained, which can be easily extended to other non-Newtonian fluids and this equation can provide theoretical basis for hydrodynamic analysis of magnetic fluid journal bearings. For the case of static loaded magnetic journal bearings, the influence of magnetic fluid effects on the lubrication performance is studied under various eccentricity ratios, magnetic intensity and concentration. The numerical results show that: with the increasing of concentration, the bearing capacity is obviously increased; the increase magnitude is larger when the eccentricity ratio is large. Under the effect of magnetic field, the bearing capacity increasing with the increasing of magnetic field intensity. When the eccentricity is small, the side leakage is highly decreased. It can be completely eliminate by appropriately designing the bearing geometry and the magnetic field which can’t be existed in normal journal bearings.

Based on the requirements of torque transmission for stability and saturation magnetization of magnetorheological fluid (MRF), an orthogonal test was designed to arrange for the preparation of MRF. MRF was prepared by chemical co-precipitation method, in which Fe3O4 nano-particles were coated with polyethylene glycol(PEG-4000). The size and distribution of particles were observed by transmission electron microscope (TEM). The saturation magnetization was measured by vibrating sample magnetometer(VSM). Through analysis of variance of orthogonal test,an optimal method for preparing a highly stable and saturation magnetization MRF was summarized. Four main parameters in preparation of MRF were discussed, including the rate of amount of substance between Fe2+and Fe3+, the rate of amount of substance between PEG-4000 and Fe2+, reaction time and the reaction temperature. It has important practical significance on the study of magnetorheological transmission device.