Journal of Magnetism and Magnetic Materials 283 (2004) 335–343 Magnetorheological suspension based on mineral oil, iron and graphite micro-particles Ioan Bica Department of Physics, Faculty of Physics, West University of Timisoara, Bd. V. Parvan, no. 4, 1900 Timisoara, Romania Received 24 March 2004; received in revised form 9 April 2004 Available online 26 June 2004 Abstract The paper presents the process of obtaining magnetorheological suspensions based on mineral oil, iron and graphite micro-particles and thermal decomposition of Fe 2 (CO) 9 . The suspension is characterized by its magnetic and magnetorheological properties. The device presented in the paper is used to determine the electrical conductivity of the suspension under the influence of the magnetic field and to interpret the results obtained in this manner. r 2004 Elsevier B.V. All rights reserved. PACS: 75.50.T Keywords: Magnetorheological suspensions; Graphite; Iron micro-particles; Magnetic field; Electrical conductivity 1. Introduction Magnetorheological suspensions (MRS) are polyphase fluids. They comprise a liquid (silicon oil, mineral oil, etc), the stearic acid and magnetic micro-particles [1–3]. The orientation of the latter ones follows the lines of the external magnetic field. The strength of the particle chains depends on the intensity of the magnetic field, the dimen- sion of the particles, the concentration of the suspensions, and on the magnetic properties of the micro-particles [4–12]. Sensible manifestations of the viscosity of the suspension in magnetic field. For suitable values of the intensity of the magnetic field, the suspension Bingham plastic [11–15]. These properties of MRS are successfully used in the following areas:  dampers for the attenuation of vibrations [16–20] and absorption of seismic shocks [20–22];  under the influence of brakes and clutches with pre-established coupling coefficients an external magnetic field [16,23,24];  manufacturing of orthopedic protheses [24,25] and, last but not least, in bio-medical studies [26]. ARTICLE IN PRESS www.elsevier.com/locate/jmmm 0304-8853/$ - see front matter r 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jmmm.2004.05.036 E-mail address: ibica2@yahoo.com (I. Bica).