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Fabrication of cellular cordierite foams
Cordierite foams were fabricated by the polymer foam replication process, where a polyurethane (PU) template is infiltrated with slurries containing appropriate binders and ceramic particles, followed by the removal of excess slurry, burning out of the polymer to leave a ceramic replica of the polyurethane and finally high temperature sintering. Two PU foam grades of the same density (0,021 g/cm3) were used as templates. The structure of the sintered foams was evaluated through density measurements, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rheological studies showed that optimum dispersion and stabilisation conditions were achieved for aqueous slurries containing 40 vol% of solids, 2 wt% of bentonite and 0,8 wt% of dispersant. Differential thermal analysis (DTA) was used to optimise the burnout of the polymer. Upon heating, decompositon of the polymer occurs, resulting in vaporisation as well as formation of a melt around 300 deg C. Cracks were observed by SEM on the struts' surface of the fabricated foams. The struts had an angular cross-section and cracks were seen along the cell edges and the cell walls. The density of the sintered foams was typically 20 % of the struts density. The volumetric shrinkage was approximately 30 % and the linear shrinkage appeared fairly isotropic.
Fabrication of cellular cordierite foams
Cordierite foams were fabricated by the polymer foam replication process, where a polyurethane (PU) template is infiltrated with slurries containing appropriate binders and ceramic particles, followed by the removal of excess slurry, burning out of the polymer to leave a ceramic replica of the polyurethane and finally high temperature sintering. Two PU foam grades of the same density (0,021 g/cm3) were used as templates. The structure of the sintered foams was evaluated through density measurements, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rheological studies showed that optimum dispersion and stabilisation conditions were achieved for aqueous slurries containing 40 vol% of solids, 2 wt% of bentonite and 0,8 wt% of dispersant. Differential thermal analysis (DTA) was used to optimise the burnout of the polymer. Upon heating, decompositon of the polymer occurs, resulting in vaporisation as well as formation of a melt around 300 deg C. Cracks were observed by SEM on the struts' surface of the fabricated foams. The struts had an angular cross-section and cracks were seen along the cell edges and the cell walls. The density of the sintered foams was typically 20 % of the struts density. The volumetric shrinkage was approximately 30 % and the linear shrinkage appeared fairly isotropic.
Fabrication of cellular cordierite foams
Costa Oliveira, F.A. (author) / Dias, S. (author) / Mascarenhas, J. (author) / Ferreira, J.M.F. (author) / Olhero, S. (author) / Dias, D. (author)
2004
5 Seiten, 3 Bilder, 1 Tabelle, 5 Quellen
Conference paper
English
Fabrication of Cellular Cordierite Foams
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