Effect of the Interparticle Pair Potential on the Rheological Behavior of Zirconia Powders: I, Electrostatic Double Layer Approach

Abstract

Aqueous slurries containing 20 vol% ZrO 2 powder doped with 3 mol% Y 2 O 3 were prepared by first dispersing the powder at pH 11, then adding 0.1M to 1.0M tetramethylammonium chloride (TMACl), or 1.0M of TPACl, CsCl, and LiCl to produce different, weakly attractive particle networks. The particle pair potentials in the slurries were investigated by viscosity versus shear rate measurements. Slurries exhibited increasing viscosities (at a given shear rate) with increasing salt concentration and decreasing (unhydrated) counterion size. The viscosities for these weakly attractive networks were intermediate to dispersed (pH 11 without added salt) and flocced (isoelectric point, pH 7.5) slurries. Cylindrical bodies were consolidated from these slurries by pressure filtration at different applied pressures. The bodies consolidated from slurries formulated with TMACl had the highest packing densities relative to those consolidated from a flocculated slurry, but the relative densities were much lower than those achieved from bodies consolidated from a dispersed slurry. The plastic or brittle nature of these bodies was determined in uniaxial compression. Powder compacts consolidated from flocced slurries and slurries coagulated with 1M TMACl, CsCl, and LiCl showed plastic behavior for filtration pressures <7.5 MPa. Results for ZrO 2 will be compared with those previously obtained for Al 2 O 3 , which produces plastic, consolidated bodies over a much broader range of slurry conditions.

Hydrothermal Synthesis of Nanosized Titania Powders: Influence of Tetraalkyl Ammonium Hydroxides on Particle Characteristics

“…The peptization effect of TANOHs could be attributed to both of their ionic parts-OH Ϫ anions and tetraalkyl ammonium (TAN ϩ ) cationsbecause neither of them alone could act as a peptizer. For example, tetramethyl ammonium chloride was used as a flocculating agent for a ZrO 2 suspension, 13 whereas NH 3 ⅐H 2 O could not peptize an amorphous TiO 2 precipitate, as reported in our previous work. 7 The only difference between NH 3 ⅐H 2 O and TANOHs lies in the larger cation sizes of TANOHs.…”

Electrokinetic studies of metal oxides in the presence of alkali trichloroacetates, trifluoroacetates, and trifluoromethanesulfonates

“…Salts of ammonium [4][5][6][7] and of tetraalkylammonium [8][9][10] with anions from Table 1, on the one hand, and short-chain carboxylates [11], salicylate [12], and trifluoromethanesulfonate [13] of alkali metals, on the other, were used as supporting electrolytes. These electrolytes gave PZC/IEP similar to the values recommended in Ref.…”

Role of deflocculants on the rheological properties of boehmite sol

“…This interest is not only to obtain improved microstructure and homogeneity, but also to tailor the rheological properties of the suspension [1]. The effect of interparticle potential on the rheological behavior of ceramic slurries has been reported in literature [2]. The system that contains an organic (polyelectrolyte) dispersant plays an important role in colloidal processing.…”