Low temperature mullite crystallization in Al- and Si-alkoxide derived homogeneous gels

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

A homogeneous mullite gel (3:2 Al2O3:SiO2 molar ratio) was made from tetraethoxysilane (TEOS) and aluminum isopropoxide (Al(OCH(CH3)2)3) at room temperature within a relatively quick three days. Mullite was the only crystalline phase to form during calcination; metastable phases like aluminosilicate spinel did not appear. When heated at 20 °C/min, crystalline mullite (65 mol% Al2O3) started forming at 575 °C and reached 27 wt.% by 900 °C. Major crystallization occurred at ~ 1000 °C with a concurrent increase of Al2O3 concentration (68-69 mol%) in the mullite phase. The alumina content decreased towards stoichiometric (3Al2O3·2SiO2) mullite at even higher temperatures. When the gel remained in the amorphous state, low temperature preheating significantly improved crystallization at higher temperatures. After preheating at 425 °C for 24 h, 78 wt.% of the final product was crystallized when it was subsequently annealed at 750 °C for 5 min. Only 20 wt.% crystallized without preheating.

Original languageEnglish (US)
Pages (from-to)2631-2634
Number of pages4
JournalMaterials Letters
Volume63
Issue number30
DOIs
StatePublished - Dec 31 2009

Fingerprint

Mullite
alkoxides
Crystallization
Gels
gels
crystallization
Preheating
heating
roasting
Temperature
spinel
Crystalline materials
aluminum oxides
Metastable phases
Aluminosilicates
aluminum
Aluminum Oxide
Calcination
room temperature
products

Keywords

  • Aluminosilicates
  • Crystallization
  • Mullite
  • Sol-gel preparation

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering
  • Mechanics of Materials

Cite this

Low temperature mullite crystallization in Al- and Si-alkoxide derived homogeneous gels. / He, Feng; Petuskey, William.

In: Materials Letters, Vol. 63, No. 30, 31.12.2009, p. 2631-2634.

Research output: Contribution to journalArticle

@article{cd5a529bf5cb46c39e893e4484679aec,
title = "Low temperature mullite crystallization in Al- and Si-alkoxide derived homogeneous gels",
abstract = "A homogeneous mullite gel (3:2 Al2O3:SiO2 molar ratio) was made from tetraethoxysilane (TEOS) and aluminum isopropoxide (Al(OCH(CH3)2)3) at room temperature within a relatively quick three days. Mullite was the only crystalline phase to form during calcination; metastable phases like aluminosilicate spinel did not appear. When heated at 20 °C/min, crystalline mullite (65 mol{\%} Al2O3) started forming at 575 °C and reached 27 wt.{\%} by 900 °C. Major crystallization occurred at ~ 1000 °C with a concurrent increase of Al2O3 concentration (68-69 mol{\%}) in the mullite phase. The alumina content decreased towards stoichiometric (3Al2O3·2SiO2) mullite at even higher temperatures. When the gel remained in the amorphous state, low temperature preheating significantly improved crystallization at higher temperatures. After preheating at 425 °C for 24 h, 78 wt.{\%} of the final product was crystallized when it was subsequently annealed at 750 °C for 5 min. Only 20 wt.{\%} crystallized without preheating.",
keywords = "Aluminosilicates, Crystallization, Mullite, Sol-gel preparation",
author = "Feng He and William Petuskey",
year = "2009",
month = "12",
day = "31",
doi = "10.1016/j.matlet.2009.09.014",
language = "English (US)",
volume = "63",
pages = "2631--2634",
journal = "Materials Letters",
issn = "0167-577X",
publisher = "Elsevier",
number = "30",

}

TY - JOUR

T1 - Low temperature mullite crystallization in Al- and Si-alkoxide derived homogeneous gels

AU - He, Feng

AU - Petuskey, William

PY - 2009/12/31

Y1 - 2009/12/31

N2 - A homogeneous mullite gel (3:2 Al2O3:SiO2 molar ratio) was made from tetraethoxysilane (TEOS) and aluminum isopropoxide (Al(OCH(CH3)2)3) at room temperature within a relatively quick three days. Mullite was the only crystalline phase to form during calcination; metastable phases like aluminosilicate spinel did not appear. When heated at 20 °C/min, crystalline mullite (65 mol% Al2O3) started forming at 575 °C and reached 27 wt.% by 900 °C. Major crystallization occurred at ~ 1000 °C with a concurrent increase of Al2O3 concentration (68-69 mol%) in the mullite phase. The alumina content decreased towards stoichiometric (3Al2O3·2SiO2) mullite at even higher temperatures. When the gel remained in the amorphous state, low temperature preheating significantly improved crystallization at higher temperatures. After preheating at 425 °C for 24 h, 78 wt.% of the final product was crystallized when it was subsequently annealed at 750 °C for 5 min. Only 20 wt.% crystallized without preheating.

AB - A homogeneous mullite gel (3:2 Al2O3:SiO2 molar ratio) was made from tetraethoxysilane (TEOS) and aluminum isopropoxide (Al(OCH(CH3)2)3) at room temperature within a relatively quick three days. Mullite was the only crystalline phase to form during calcination; metastable phases like aluminosilicate spinel did not appear. When heated at 20 °C/min, crystalline mullite (65 mol% Al2O3) started forming at 575 °C and reached 27 wt.% by 900 °C. Major crystallization occurred at ~ 1000 °C with a concurrent increase of Al2O3 concentration (68-69 mol%) in the mullite phase. The alumina content decreased towards stoichiometric (3Al2O3·2SiO2) mullite at even higher temperatures. When the gel remained in the amorphous state, low temperature preheating significantly improved crystallization at higher temperatures. After preheating at 425 °C for 24 h, 78 wt.% of the final product was crystallized when it was subsequently annealed at 750 °C for 5 min. Only 20 wt.% crystallized without preheating.

KW - Aluminosilicates

KW - Crystallization

KW - Mullite

KW - Sol-gel preparation

UR - http://www.scopus.com/inward/record.url?scp=70350007156&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=70350007156&partnerID=8YFLogxK

U2 - 10.1016/j.matlet.2009.09.014

DO - 10.1016/j.matlet.2009.09.014

M3 - Article

VL - 63

SP - 2631

EP - 2634

JO - Materials Letters

JF - Materials Letters

SN - 0167-577X

IS - 30

ER -