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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

Peter Mechnich*
Affiliation:
German Aerospace Center (DLR), Institute of Materials Research, Köln 51147, Germany
Ferdinand Flucht
Affiliation:
German Aerospace Center (DLR), Institute of Materials Research, Köln 51147, Germany
Martin Schmücker
Affiliation:
German Aerospace Center (DLR), Institute of Materials Research, Köln 51147, Germany
*
a)Address all correspondence to this author. e-mail: peter.mechnich@dlr.de
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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.

Type
Invited Articles
Copyright
Copyright © Materials Research Society 2017 

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Footnotes

Contributing Editor: Eugene Medvedovski

References

REFERENCES

Schneider, H., Fischer, R.X., and Schreuer, J.: Mullite: Crystal structure and related properties. J. Am. Ceram. Soc. 98(10), 2948 (2015).Google Scholar
Fischer, R.X. and Schneider, H.: The mullite-type family of crystal structures. In Mullite, Schneider, H. and Komarneni, S., eds. (Wiley-VCH, Weinheim, 2005); pp. 146.Google Scholar
Komarneni, S., Schneider, H., and Okada, K.: Processing of mullite ceramics. In Mullite, Schneider, H. and Komarneni, S., eds. (Wiley-VCH, Weinheim, 2005); pp. 286306.Google Scholar
Carter, D.S.: Advantages of mullite-fiber linings for high-temperature furnaces. Available at: http://www.industrialheating.com/articles/91900-advantages-of-mullite-fiber-linings-for-high-temperature-furnaces (accessed November 3, 2016).Google Scholar
Zhang, R., Ye, C., Hou, X., Li, S., and Wang, B.: Microstructure and properties of lightweight fibrous porous mullite ceramics prepared by vacuum squeeze moulding technique. Ceram. Int. 42(13), 14843 (2016).Google Scholar
Liu, M.M., Liu, J.C., Wang, M.C., and Yun, Z.Q.: Preparation and properties of SiO2/Al2O3–SiO2 fiber mat composite materials. Key Eng. Mater. 680, 129 (2016).Google Scholar
Zhang, J., Dong, X., Hou, F., Du, H., Liu, J., and Guo, A.: Effect of mullite fiber content on the microstructure and properties of porous mullite fiber/silica composite. Ceram. Int. 42(5), 6520 (2016).Google Scholar
Zhang, J., Dong, X., Hou, F., Du, H., Liu, J., and Guo, A.: Effects of fiber length and solid loading on the properties of lightweight elastic mullite fibrous ceramics. Ceram. Int. 42(4), 5018 (2016).Google Scholar
Zang, W., Guo, F., Liu, J., Du, H., Hou, F., and Guo, A.: Lightweight alumina based fibrous ceramics with different high temperature binder. Ceram. Int. 42(8), 10310 (2016).Google Scholar
Dong, X., Lv, H., Sui, G., Liu, J., Guo, A., Tao, X., Xu, X., and Du, H.: Synthesis and properties of lightweight fibrous ceramics with a 3D skeleton structure prepared by infiltration. Mater. Sci. Eng., A 635, 43 (2015).Google Scholar
Dong, X., Sui, G., Liu, J., Guo, A., Ren, S., Wang, M., and Du, H.: Mechanical behavior of fibrous ceramics with a bird’s nest structure. Compos. Sci. Technol. 100, 92 (2014).CrossRefGoogle Scholar
Dong, X., Sui, G., Yun, Z., Wang, M., Guo, A., Zhang, J., and Liu, J.: Effect of temperature on the mechanical behavior of mullite fibrous ceramics with a 3D skeleton structure prepared by molding method. Mater. Des. 90, 942 (2016).Google Scholar
Ma, X., Hu, X., Du, H., and Lv, H.: An unoriented three dimension framework (network) of fibrous porous ceramics prepared by freeze casting. J. Eur. Ceram. Soc. 36(3), 797 (2016).Google Scholar
Liu, Q., Xue, T., Yang, L., Hu, X., and Du, H.: Controllable synthesis of hierarchical porous mullite fiber network for gas filtration. J. Eur. Ceram. Soc. 36(7), 1691 (2016).CrossRefGoogle Scholar
Ohtsuki, Y., Nakahara, Y., and Sugiyama, N.: New mullite fiber and its application in the steel industry. In UNITECR ’91, The German Refractories Association, ed. (Stahl und Eisen, Düsseldorf, Germany, 1992); pp. 557566.Google Scholar
Schneider, H., Merwin, L., and Sebald, A.: Mullite formation from non-crystalline precursors. J. Mater. Sci. 27(3), 805 (1992).Google Scholar
Kakikura, E., Sasaki, T., Noguchi, Y., and Itagaki, K.: Performance advantages of polycrystalline alumina fiber non-intumescent mat in catalytic converters. SAE Technical Paper 2005-01-1627, 2005.Google Scholar
Steinhauser, U., Braue, W., Göring, J., Kanka, B., and Schneider, H.: A new concept for thermal protection of all-mullite composites in combustion chambers. J. Eur. Ceram. Soc. 20, 651 (2000).Google Scholar
Ban, T. and Okada, K.: Structure refinement of mullite by the rietveld method and a new method for estimation of chemical composition. J. Am. Ceram. Soc. 75(1), 227 (1992).Google Scholar
Radsick, T., Saruhan, B., and Schneider, H.: Damage tolerant oxide/oxide fiber laminate composites. J. Eur. Ceram. Soc. 20, 545 (2000).CrossRefGoogle Scholar