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Manufacturing of porous mullite fiber compacts by uniaxial hot pressing of semicrystalline MAFTEC® MLS-2 organic bound mats
Published online by Cambridge University Press: 29 June 2017
Abstract
Highly porous and fully crystalline mullite fiber compacts were fabricated by uniaxial hot pressing of stacked short-fiber mats without binders or sintering aids. The special feature of this new fabrication method is the use of MAFTEC® organic bound mat (OBM) type fiber mats consisting of semicrystalline “MLS-2” short fibers. In contrast to conventional polycrystalline mullite fibers, semicrystalline MLS-2 fibers consist of amorphous silica and nanoscale transitional alumina. Due to this special microstructure, MLS-2 fibers are less prone to fiber breakage upon shear load and therefore can well withstand pressure-assisted consolidation. Hot pressing of stacked OBM to highly porous fiber compacts is facilitated by the thermally driven softening of amorphous silica above 900 °C; favorable deformation and consolidation rates are achieved above 1050 °C. Above 1250 °C the mullite is crystallized at the expense of amorphous silica and simultaneously both deformation and consolidation comes to an end. Obtained MAFTEC OBM-derived fiber compacts consist only of crystalline mullites, and therefore mechanical properties are favorably retained at high temperatures.
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- Information
- Journal of Materials Research , Volume 32 , Issue 17: Focus Issue: Achieving Superior Ceramics and Coating Properties through Innovative Processing , 14 September 2017 , pp. 3294 - 3301
- Copyright
- Copyright © Materials Research Society 2017
Footnotes
Contributing Editor: Eugene Medvedovski
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