Anisotropic grain growth in diphasic-gel-derived titania-doped mullite

Seong Hyeon Hong, Gary L. Messing

Research output: Contribution to journalArticle

105 Citations (Scopus)

Abstract

Densification and anisotropic grain growth in diphasic-gel-derived, titania-doped mullite were studied. Titania enhanced initial and intermediate stage densification in diphasic mullite gels by reducing the glass viscosity. Rodlike anisotropic mullite grains started to grow in titania-doped diphasic mullite gels once a dense, equiaxed microstructure was achieved. The onset temperature for anisotropic grain growth decreased with increasing titania concentration because the sintering temperature for final-stage densification decreased. The lowest onset temperature for anisotropic grain growth was ∼1500°C in 5 wt% titania-doped mullite. The aspect ratio and area fraction of anisotropic mullite grains increased with higher titania concentration and were strongly dependent on the initial titania particle size. Kinetic studies demonstrated that anisotropic grain growth in titania-doped diphasic mullite gels followed the empirical equation G n - G 0 n = Kt, with growth exponents of 3 and 6 for the length [001] and thickness [110] directions, respectively. The activation energies for grain growth were 690 kJ/mol for the length and 790 kJ/mol for the thickness directions.

Original languageEnglish (US)
Pages (from-to)1269-1277
Number of pages9
JournalJournal of the American Ceramic Society
Volume81
Issue number5
StatePublished - May 1 1998

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Mullite
Grain growth
Gels
Titanium
Densification
aluminosilicate
titanium dioxide
Temperature
Aspect ratio
Sintering
Activation energy
Particle size
Viscosity
Glass
Microstructure
Kinetics

All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry

Cite this

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abstract = "Densification and anisotropic grain growth in diphasic-gel-derived, titania-doped mullite were studied. Titania enhanced initial and intermediate stage densification in diphasic mullite gels by reducing the glass viscosity. Rodlike anisotropic mullite grains started to grow in titania-doped diphasic mullite gels once a dense, equiaxed microstructure was achieved. The onset temperature for anisotropic grain growth decreased with increasing titania concentration because the sintering temperature for final-stage densification decreased. The lowest onset temperature for anisotropic grain growth was ∼1500°C in 5 wt{\%} titania-doped mullite. The aspect ratio and area fraction of anisotropic mullite grains increased with higher titania concentration and were strongly dependent on the initial titania particle size. Kinetic studies demonstrated that anisotropic grain growth in titania-doped diphasic mullite gels followed the empirical equation G n - G 0 n = Kt, with growth exponents of 3 and 6 for the length [001] and thickness [110] directions, respectively. The activation energies for grain growth were 690 kJ/mol for the length and 790 kJ/mol for the thickness directions.",
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Anisotropic grain growth in diphasic-gel-derived titania-doped mullite. / Hong, Seong Hyeon; Messing, Gary L.

In: Journal of the American Ceramic Society, Vol. 81, No. 5, 01.05.1998, p. 1269-1277.

Research output: Contribution to journalArticle

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AU - Messing, Gary L.

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