Pore Structure and Thermal Stability of Mesoporous Mullite Fibers Prepared by Crystallization and Selective Leaching of Al2O3-SiO2 Glass Fibers

Abstract Porous mullite fibers were prepared by crystallization and selective leaching of Al2O3-SiO2 glass fibers using buffered HF-NH4F(BHF) aqueous solutions. The optimum concentration of BHF solution for selective leaching of the fibers was 0.9 mass% HF and 17.0 mass% NH4F. By firing at 1000–1300...

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Bibliographic Details
Published in:Journal of porous materials, Vol. 6 (1999), p. 119-126
Other Involved Persons: Takei, Takahiro ; Hayashi, Shigeo ; Yasumori, Atsuo ; Okada, Kiyoshi
Format: electronic Article
Language:English
ISSN:1573-4854
Item Description:Copyright: Copyright 1999 Kluwer Academic Publishers
Physical Description:Online-Ressource
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  • Abstract Porous mullite fibers were prepared by crystallization and selective leaching of Al2O3-SiO2 glass fibers using buffered HF-NH4F(BHF) aqueous solutions. The optimum concentration of BHF solution for selective leaching of the fibers was 0.9 mass% HF and 17.0 mass% NH4F. By firing at 1000–1300°C, the glass fibers changed into composite texture of mullite and glassy phase. Since the pores in the fibers were formed by selective leaching of glassy phase among mullite grains, they were tunable by changing the firing conditions of fibers. Pore size of the samples changed from around 4 nm in the 1100°C fired sample to 16 and 40 nm in the 1200 and 1300°C fired samples, respectively. The highest specific surface area obtained was around 30 m2/g, when the fibers were heat treated at 1200°C for 24 h and leached for 20 h in 0.9 mass% HF-17.0 mass% NH4F solution. From the thermal stability tests of the porous mullite fibers, its specific surface area was found to be maintained up to 1200–1300°C.