Effects of preparation process of ferrite slurry on the properties of spray-dried granules and their compact

Abstract

The effects of physical properties of MnZn-ferrite slurry on the quality of granules and compacts were discussed. Emphasis is laid on the order of addition of a dispersant and poly vinyl alcohol (PVA) to the starting ferrite slurry. The composite slurries were prepared either by simultaneous addition of dispersant and PVA (Slurry S), sequential addition of PVA followed by dispersant (Slurry D) or dispersant followed by PVA (Slurry P). The viscous flow behavior of all the composite slurries was analyzed on the basis of the Harschel-Bulkley model. Slurry P showed the highest yield point and plastic viscosity. The density of the granules produced from Slurry P was the lowest and its compacts showed the lowest bending strength and the smallest Weibull modulus. These phenomena were interpreted in terms of the irreversible absorption and interaction of dispersant and PVA.