Dispersion of Barium Ferrite Particles for Slip Casting in Magnetic Field
Water-based slurries containing barium ferrite particles have been prepared and slip cast in magnetic field. This paper presents the characteristics of the suspensions in terms of Iso-Electric Points (IEP) and zeta potential that were evaluated through pH titration and polymer adsorption. Both enlarging the specific surface area of particles by planetary milling and adjusting the pH to low value apparently increase the zeta potentials. Stable slurry was obtained by adding polyethylene glycol (PEG) into the suspension at pH = 2 ~ 3.5. The steric repulsion plays key role in dispersion and PEG films served as insulative layers and mechanically kept particles from contact each other. The barium ferrite particles formed many stacks of plates during slip casting, which either aligned randomly without magnetic field applied or regularly aligned to form textured structure when magnetic field was applied.
T. Ohji, T. Sekino and K. Niihara
J. L. Li et al., "Dispersion of Barium Ferrite Particles for Slip Casting in Magnetic Field", Key Engineering Materials, Vols. 317-318, pp. 143-146, 2006