Improvement of the Dispersion of Al 2 O 3 Slurries Using EDTA‐4Na

Polyacrylic acid (PAA) is known to be an effective dispersant for Al 2 O 3 powder in aqueous media. However, at high solid loading (>55 vol%), the dispersion of the Al 2 O 3 suspensions became difficult with only PAA as a dispersant. In this paper, ethylenediaminetetraacetic acid, tetrasodium salt, dihydrate (EDTA‐4Na) was introduced to improve the dispersion of the Al 2 O 3 suspensions. With the aid of EDTA‐4Na, the adsorption amount of sodium polyacrylic acid (PAA‐Na) increased, while the apparent viscosity of 60 vol% Al 2 O 3 slurries decreased significantly. Particle size measurements showed that EDTA‐4Na could help to reduce larger agglomerates, possibly by modifying the adsorbed layer thickness. The interactions between EDTA‐4Na and PAA‐Na were studied using Fourier‐transform infrared spectroscopy analysis. Results showed that it was possible to introduce EDTA‐4Na as the second dispersant to improve the dispersion of high solid content Al 2 O 3 slurries.