Coagulation in processing of ceramic suspensions: Powder size distribution effects

Abstract

The origin of agglomerates in slips and slurries of ceramic particles due to particle size distribution effects is considered. Since agglomerates have been related to flaws in sintered ceramic bodies, the parameters which control coagulation of particles into agglomerates need to be defined. Computer calculations, based on Derjaguin, Landau, Verwey, and Overbeek theory, have been used to predict stability curves for particulate suspensions with log normal particle size distributions. Two regimes appear in the calculations: at width parameters (σz) corresponding to the inherent distribution of a powder the coagulation time decreases rapidly with increasing polydispersity; at larger σzs corresponding to mixing different sizes of powders to get very broad distributions the coagulation time decreases with increasing polydispersity. This change in behavior occurs at aproximately σz=1.0.