Effect of acrylic copolymer adsorption on the colloidal stability of a 3Y-TZP suspension

This article investigates the adsorption of an acrylic acid/acrylate copolymer on 3Y-TZP and its influence on the stability of colloidal 3Y-TZP aqueous suspensions. Potentiometric titration shows that ionization degree of the copolymer increases from 0 at pH 2.5 to 1 at pH 9. The adsorption is characterized using the chemical oxygen demand (COD) method. The influences of pH, copolymer concentration and electrolyte concentration are investigated. The adsorption density is found to increase pronouncedly with increasing KNO3 concentration at higher pH, while is almost independent upon KNO3 concentration at lower pH. The zeta potential of Y-TZP decreases as a result of copolymer adsorption. The optimum copolymer concentration at pH 8.8 is around 2 dry mass base (dmb)%, determined by both effective diameter measurements and theological characterization. The stabilization of the copolymer for the suspension is also evidenced by scanning electron microscopy (SEM) analysis of the sediments. The fractal dimensions of sediments obtained with and without dispersant were determined and compared using the limited fractal dimension method. (C) 2002 Elsevier Science Ltd. All rights reserved.