Fabrication of Stable Al₂O₃ Slurries and Dense Green Bodies Using Wet Jet Milling

Abstract

A wet jet milling process was used as a novel method to prepare Al2O3 slurries. The wet jet‐milled slurries showed very low viscosity compared with the ball‐milled slurries. Moreover, the viscosity of the wet jet‐milled slurries was constant for long times, whereas that of the ball‐milled slurries increased rapidly with time. Al2O3 particles after wet jet milling retained initial surface conditions, although Al2O3 particles after ball milling yielded more OH groups on the surface. Casting rate was sensitive to the solid content and preparation method of slurry. The relative density of the green bodies prepared from the wet jet‐milled slurries was about 65% or more and was independent of the slurry solid content. On the other hand, the relative density of the green bodies prepared from the ball‐milled slurries increased with increasing solid content and was higher than 60% at the solid content of 50% by volume. Linear shrinkage of the sintered bodies prepared from the wet jet‐milled slurries was very low and independent of the solid content of the slurry whereas that of the sintered bodies prepared from the ball‐milled slurries increased with decreasing solid content.

Comparison of aqueous and non-aqueous tape casting of fully stabilized ZrO2 suspensions

“…The as received powder (dash line -0 h) is bimodal with fine particles of~0.5 μm diameter, together with soft agglomerated particles with diameter ≥ 2 μm (the second smaller peak). Reagglomeration takes place, with milling times over 3 h. It does not correspond with the results of Omura [22] where the 4 h ball milling was not sufficient for full de-agglomeration of an alumina powder. The possible explanation can be the higher solid content in the work in comparison with 25 vol.% in our case and also different properties of the used powders e.g.…”

State of the Dispersant and Particle Surface During Wet‐Jet Milling for Preparation of a Stable Slurry

“…A commercially available high‐purity α‐Al 2 O 3 (AKP‐20, Sumitomo Chemical, Tokyo, Japan) with an average particle size ( D 50 ) of 0.57 μm was used in the present work 25 . The dispersant used in this study was an NH 4 + salt of poly(acrylic acid) (PAA–NH 4 + , Mw 8000, Aron A6114, Toagousei, Japan).…”

“…The length of the polymer chain, adsorbed on the particle surface, governs the closest approach of particles to each other, thus, conferring a long‐term stability to the slurry. After ball milling, however, ceramic particles in a slurry have a tendency to reflocculate due to an increase in the number of the active sites induced on the surface of particles by the impact and shearing action of the grinding medium 21–25 . Recently, in our previous works, 25–27 it has been demonstrated that wet‐jet‐milled slurries exhibited distinctly different stability behavior compared with ball‐milled ones in terms of reflocculation efficiency, rheological properties, and packing density.…”

“…After ball milling, however, ceramic particles in a slurry have a tendency to reflocculate due to an increase in the number of the active sites induced on the surface of particles by the impact and shearing action of the grinding medium. [21][22][23][24][25] Recently, in our previous works, [25][26][27] it has been demonstrated that wet-jet-milled slurries exhibited distinctly different stability behavior compared with ball-milled ones in terms of reflocculation efficiency, rheological properties, and packing density. The viscosity of the ball-milled slurry increased rapidly with time, whereas the viscosity of the wet-jet-milled slurry was stable for a long time at a value of B10 mPa Á s. In addition, the wet-jet-milled slurry was less reflocculated compared with the ball-milled one.…”

Fabrication of transparent MgAl2O4 spinel through homogenous green compaction by microfluidization and slip casting

“…However, most studies in the field of ceramic processing have not specifically investigated the microfluidization process. Limited studies of Al 2 O 3 and ZnO using wet-jet milling were conducted by only one research group of AIST in Japan [20][21][22][23].…”