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Boron mullite: Formation and basic characterization

delete2012-12-01
delete40
PRE
AI
H
Hanna Lührs *
R
R. X. Fischer
H
Hartmut Schneider
DOI:10.1016/j.materresbull.2012.08.064delete
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Abstract

Abstract

En 中文
A series of boron doped mullites (B-mullite) was prepared from single-phase gels with initial compositions based on a 1:1 isomorphous substitution of Si by B, starting from a 3:2 mullite composition (Al4.5Si1.5O9.75). A high amount of boron (>10 mol.%) can be incorporated into the crystal structure of mullite where it most likely replaces Si. In situ phase formation of B-mullites was studied with high temperature X-ray diffraction and thermal analysis. A decrease of the formation temperature for B-mullite with increasing boron content was observed. With increasing boron content lattice parameters and c significantly decrease, while no systematic evolution of a is observed. Long annealing at 1400 degrees C results in decomposition of B-mullite to boron free mullite and alpha-alumina. At 800 degrees C B-mullite appears to be stable over a period of at least 12 days. The mean thermal expansion coefficient was reduced by 15% upon incorporation of boron which makes the material technologically interesting. (C) 2012 Elsevier Ltd. All rights reserved.
Keywords:
Inorganic compounds
Ceramics
Chemical synthesis
X-ray diffraction
Thermal expansion

Journal

Materials Research Bulletin cover
Materials Research Bulletin
IF:
5.7
Papers:
1.3W
Citations:
2.9W

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U
University of Bremen
Scholars:
8.1K
Papers: 7.2K
Citations: 1.1W