Effect of ultrasonication on colloidal dispersion of Al2O3 and ZrO2 powders in pH controlled suspension

Tohru S. Suzuki, Yoshio Sakka, Keishi Nakano, Keijiro Hiraga

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

Colloidal processing is well known to be an effective method to avoid the agglomeration of particles in powder processing. In this method, particles are dispersed by the electrostatic repulsion arising from their surface charge which can be controlled by the pH-value of the suspension. Since fine particles tend to agglomerate, however, additional redispersion treatment is necessary to obtain dispersed suspension of submicrometer-sized particles. In this study was used ultrasonication such as additional re-dispersion treatment for the dispersion of fine powders. Al2O3 and ZrO2 used in this study were high-purity fine powders and their particle sizes were 0.2 and 0.07 μm, respectively. Three types of suspensions were prepared under different conditions of mixing with ultrasonication for various treatment periods. With increasing degree of ultrasonication, the apparent viscosity of suspension decreased, the dispersion of the particles in the suspensions was promoted and the relative densities of the compacts and the sintered specimens increased, because of a decrease in both total pore volume and the pore size. The microstructure of the sintered specimen prepared from the sufficiently ultrasonicated suspension was very fine, which resulted in high superplasticity.

Original languageEnglish
Pages (from-to)689-692
Number of pages4
JournalMaterials Transactions, JIM
Volume39
Issue number6
DOIs
Publication statusPublished - 1998 Jun
Externally publishedYes

Keywords

  • Alumina
  • Colloidal processing
  • Fine microstructure
  • Particle dispersion
  • Superplasticity
  • Ultrasonication
  • Zirconia

ASJC Scopus subject areas

  • Engineering(all)

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