Study of structural changes in magneto-rheological fluids by acoustic spectroscopy

The changes in structural arrangement in silicon oil based magneto-rheological fluids with carbonyl iron particles upon the effect of an external magnetic were studied by acoustic spectroscopy. The attenuation of acoustic waves was measured for a jump change of the magnetic field at temperature 20 °C for various magnetic particles concentrations. The relaxation effects for the acoustic attenuation after switching off the magnetic field and its decrease to the same value as for clean synthetic oil were observed. The change in attenuation coefficients of acoustic waves in magneto-rheological fluid versus angle between the wave vector and direction of the applied magnetic field has been measured, too. From the measured anisotropy of attenuation coefficient structural change of magneto-rheological fluid in the magnetic field is evident. The observed influences of the magnetic field and concentration on the investigated liquids structure are discussed.