title: Description and performance of a fully automatic device for the study of the sedimentation of magnetic suspensions.
abstract: In this paper we describe an experimental setup for the automatic determination of the sedimentation behavior of magnetic suspensions (i.e., disperse systems consisting on ferro- or ferri-magnetic particles in a suitable fluid) of arbitrary volume fraction of solids. The device is based on the evaluation of the inductance of a thin coil surrounding the test tube containing the sample. The inductance L is evaluated from the measurement of the resonant frequency of a parallel LC circuit constructed with the coil and a capacitor of known capacitance. The coil can be moved vertically along the tube at specified steps and time intervals, and from the knowledge of L as a function of the vertical position and time, one can get an image of the particle concentration profiles at given instants of time. The performance of the device is tested against suspensions of spherical iron particles in the micrometer size range dispersed in silicone oil, with various initial concentrations of solids. The sedimentation profiles are then compared with the predictions of existing models for the settling of disperse systems of non-interacting particles.
authors.affiliation: Institute of Physical Chemistry, University of Graz, 8010 Graz, Austria.
authors.forename: G R
authors.initials: GR
authors.lastname: Iglesias
authors.forename: M T
authors.initials: MT
authors.lastname: López-López
authors.forename: A V
authors.initials: AV
authors.lastname: Delgado
authors.forename: J D G
authors.initials: JD
authors.lastname: Durán