Two-stage densification of ultrafine transition alumina seeded with α-phase particulates

H. C. Kao, W. J. Wei, Chi-Yuen Huang

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7 Citations (Scopus)

Abstract

Highly densified Al 2 O 3 was prepared from a transition (mainly θ-phase) Al 2 O 3 powder doped with α-seeds. Two thermal processing steps resulted in the densification and the θ- to α-phase transformation were characterized by thermomechanical analysis (TMA), porosimetry, scanning and transmission electron microscopies (SEM and TEM). The evolution of the grain growth and porosity were observed. The results showed that the first-stage densification in association with the θ- to α-phase transformation could be controlled to form ultrafine and uniform microstructures, and that would benefit the second-stage densification. The additional α-seeds do not only enhance the transformation rate and give a narrower pore size, but also allow the growth of uniform α-grains to sizes ca. 60 nm. The final densification properties of two seeded samples by thermal treatments were investigated revealing the effects of the transformation in the first stage and the influence of two sintering parameters, e.g. temperature and soaking time on the sintered microstructure.

Original languageEnglish
Pages (from-to)34-41
Number of pages8
JournalJournal of Ceramic Processing Research
Volume4
Issue number1
Publication statusPublished - 2003 Dec 1

All Science Journal Classification (ASJC) codes

  • Ceramics and Composites

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