Effect of 2‐Phosphonobutane‐1,2,4‐tricarboxylic Acid Adsorption on the Stability and Rheological Properties of Aqueous Nanosized 3‐mol%‐Yttria‐Stabilized Tetragonal‐Zirconia Polycrystal Suspensions

Abstract

2‐phosphonobutane‐1,2,4‐tricarboxylic acid (PBTCA) was evaluated as a dispersant for nanosized 3‐mol%‐Y2O3‐stabilized tetragonal‐ZrO2 polycrystal (3Y‐TZP) suspensions. The adsorption of PBTCA was characterized using the decolorization method of ferric 5‐nitrosalicylate complexes. Maximum adsorption of the dispersant on the 3Y‐TZP powder was found to occur at pH 3.0. At pH >3.0, the adsorbed amount decreased with increased pH. Semiquantitative analysis using auger electron spectroscopy showed that PBTCA adsorbed irreversibly on the powder. The surface charge of the powder was evaluated by measuring the zeta‐potential in dilute powder suspensions. The suspension was most effectively stabilized at high pH by the high charge induced by the adsorption of PBTCA. Rheological properties of the suspension were evaluated as a function of dispersant amount and solids loading. The optimum amount of dispersant increased with increased solids loading for solids loading >20 vol%. A stable suspension of 35 nm 3Y‐TZP particles with a solids loading as high as 32 vol% was obtained using PBTCA as dispersant, in contrast to 28 vol% when using ammonium polyacrylate (NH4PAA). Theoretical calculations of the interaction between 3Y‐TZP particles showed that the stabilization of the suspensions was attributed to a combination of the electrostatic repulsion and a steric barrier caused by the adsorbed PBTCA. Induced coupling plasma analysis showed that PBTCA could be completely burned out during sintering, which confirmed its suitability as a dispersant for 3Y‐TZP.