A device for measuring concentration and dispersion quality of rod and plate-like magnetic particle suspensions

Rheomagnetic measurement, a technique for studying the concentration and the orientation of the magnetic particles through inductance measurement, is described. The method may complement conventional techniques. Compared to conventional techniques, the rheomagnetic method is uniquely suitable for process control during the early stages of slurry production in manufacturing, since it requires little test time, measures the dispersion quality of concentrated suspensions, operates automatically, and can be placed on-line. The concepts upon which the measurement technique is based are discussed. Experimental data on the effects of particle concentration and milling of rod-like γ-Fe₂O₃ and plate-like barium-ferrite suspensions are discussed. This is the first observation reported on the rheomagnetic orientation measurement for plate-like magnetic particles and the results markedly contrast with those from the rod-like magnetic particles