Colloidal Stability and Magnetic Field-Induced Ordering of Magnetorheological Fluids Studied with a Quartz Crystal Microbalance.

Jaime Rodriguez-López,Diethelm Johannsmann,Juan De Vicente,Luis Elvira,Francisco Montero De Espinosa,Pedro Castro,Jose Morillas

doi:10.3390/s151229808

Jaime Rodriguez-López, Diethelm Johannsmann + Show 5 more

Open Access

https://doi.org/10.3390/s151229808

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Abstract

This work proposes the use of quartz crystal microbalances (QCMs) as a method to analyze and characterize magnetorheological (MR) fluids. QCM devices are sensitive to changes in mass, surface interactions, and viscoelastic properties of the medium contacting its surface. These features make the QCM suitable to study MR fluids and their response to variable environmental conditions. MR fluids change their structure and viscoelastic properties under the action of an external magnetic field, this change being determined by the particle volume fraction, the magnetic field strength, and the presence of thixotropic agents among other factors. In this work, the measurement of the resonance parameters (resonance frequency and dissipation factor) of a QCM are used to analyze the behavior of MR fluids in static conditions (that is, in the absence of external mechanical stresses). The influence of sedimentation under gravity and the application of magnetic fields on the shifts of resonance frequency and dissipation factor were measured and discussed in the frame of the coupled resonance produced by particles touching the QCM surface. Furthermore, the MR-fluid/QCM system has a great potential for the study of high-frequency contact mechanics because the translational and rotational stiffness of the link between the surface and the particles can be tuned by the magnetic field.

Highlights

Thickness shear mode (TSM) resonators consist of thin, AT-cut piezoelectric crystals covered with electrodes on both sides
The resonance parameters of a TSM resonator change when the resonator surface is brought into contact with a sample
When the sample consists of a rigid film (

Summary

Introduction

Thickness shear mode (TSM) resonators (the QCM being the most widely employed type) consist of thin, AT-cut piezoelectric crystals covered with electrodes on both sides. Even more relevant to the topic of this work is the fact that the device is sensitive to changes in the rigidity of contacts between particles and the resonator surface [12,13]. With no magnetic field applied, the particles are dispersed randomly within the carrier fluid.

Results

Conclusion