A device for measuring the concentration and dispersion quality of magnetic particle suspensions

Abstract

A technique, called rheomagnetic measurement, for studying the concentration and orientation of magnetic particles through inductance measurement is presented. The particles are oriented in a predominantly extensional flow field, and, because they are magnetic, their orientation can be detected with a weak magnetic sensing field. Because flocs of magnetic particles orient differently in a flow field than primary particles do, this method can be useful in obtaining information about the particle flocculation aspect of dispersion quality. A magnetic sensing field can also be used to detect the particle concentration in a quiescent flow. Experimental data on the effects of particle concentration and milling for rod-like gamma -Fe/sub 2/O/sub 3/ and plate-like Ba-ferrite suspensions are discussed. The results for Ba-ferrite magnetic markedly contrast with those for the rod-like magnetic particles but showed similarity with those for rod-like gamma -Fe/sub 2/O/sub 3/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>