Highly concentrated aqueous suspension containing fine SiC particles

Abstract

Effects of polyethylene glycol (PEG) dispersant and pH on the dispersion behavior of aqueous SiC slurry were investigated. High solid loading up to 62 vol% with low viscosity (202 mPa s) was achieved using fine SiC powders prepared by mechanical alloying process with the average diameter of 152 nm. The property analysis of the slurry in terms of zeta potential, particle size, sedimentation, TG-DTA analysis, and rheological measurements indicated that the optimum pH value and dispersant content of the highly concentrated slurry were pH 9 and 0.4 wt%, respectively. A SiC green body with the relative density of 62.9% was made by drying 62 vol% SiC slurry in an drying oven at 80 °C. Crack formation did not occur during drying because of the high solid loading and consequent low shrinkage rate (0.097%). In contrast, those prepared by cold isostatic press (CIP) under 200 MPa had a lower relative density of 58.8%.