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Processing of Macroporous Alumina Ceramics Using Pre-Expanded Polymer Microspheres as Sacrificial Template

1
Division of Materials Science, Luleå University of Technology, 971 87 Luleå, Sweden
2
Akzo Nobel Pulp and Performance Chemicals AB, Expancel, P.O. Box 13000, SE-850 13 Sundsvall, Sweden
*
Author to whom correspondence should be addressed.
Ceramics 2018, 1(2), 329-342; https://doi.org/10.3390/ceramics1020026
Received: 17 October 2018 / Revised: 1 November 2018 / Accepted: 2 November 2018 / Published: 6 November 2018
Shaped porous ceramics have proven to be the most adapted materials for several industrial applications, both at low and high temperatures. Recent research has been focused on developing shaping techniques, allowing for a better control over the total porosity and the pores characteristics. In this study, macroporous alumina foams were fabricated by gel-casting using pre-expanded polymeric microspheres with average sizes of 40 μm, 20 μm, and 12 μm as sacrificial templates. The gel-casting method, as well as the drying, debinding, and presintering conditions were investigated and optimized to process mechanically strong and highly porous alumina scaffolds. Furthermore, a reliable model relating the amount of pre-expanded polymeric microspheres and the total porosity of the presintered foams was developed and validated by mercury intrusion porosimetry measurements. The electron microscopy investigation of the presintered foams revealed that the size distribution and the shape of the pores could be tailored by controlling the particle size distribution and the shape of the wet pre-expanded microspheres. Highly uniform and mechanically stable alumina foams with bimodal porosity ranging from 65.7 to 80.2 vol. % were processed, achieving compressive strengths from 3.3 MPa to 43.6 MPa. Given the relatively open pore structure, the pore size distribution, the presintered mechanical strength, and the high porosity achieved, the produced alumina foams could potentially be used as support structures for separation, catalytic, and filtration applications. View Full-Text
Keywords: gel-casting; sacrificial templating; macroporous alumina; pre-expanded polymeric microspheres gel-casting; sacrificial templating; macroporous alumina; pre-expanded polymeric microspheres
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Ciurans Oset, M.; Nordin, J.; Akhtar, F. Processing of Macroporous Alumina Ceramics Using Pre-Expanded Polymer Microspheres as Sacrificial Template. Ceramics 2018, 1, 329-342.

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