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Fabrication of Low‐Density Ferrous Metallic Foams by Reduction of Chemically Bonded Ceramic Foams
Author(s) -
Verdooren A.,
Chan H. M.,
Grenestedt J. L.,
Harmer M. P.,
Caram H. S.
Publication year - 2006
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2006.01225.x
Subject(s) - materials science , composite material , ceramic foam , metal foam , relative density , foaming agent , ceramic , carbon nanofoam , ferrous , compressive strength , oxide , metal , microstructure , aluminium , metallurgy , porosity
Closed cell ferrous foams were fabricated using a chemically bonded oxide ceramic foam precursor. The major constituent of the ceramic foam precursor was iron oxide (Fe 2 O 3 ), which was mixed with various foaming/setting additives. The density of the foam was modified by varying the ambient pressure under which foaming was carried out. Further, a magnesium–ammonium phosphate‐based cement system was utilized to promote more rapid setting times and hence minimize foam collapse. The oxide foam was then reduced by heating at 1240°C in a non‐flammable hydrogen/inert gas mixture to obtain metallic foams. The relative density of samples foamed under a reduced pressure (∼380 Torr) was 0.13±0.006, which is the lowest value reported to date for a closed cell ferrous foam. A relative density of 0.21±0.01 was achieved for samples foamed under atmospheric pressure. With regard to the foam morphology, the average cell diameter was 1.41±0.6 mm for the low‐density (LD) foams, and 0.96±0.2 mm for the high‐density (HD) foams. The iron foams were tested in compression and yielded an average compressive strength of 11±1 and 19±4 MPa for the LD and HD foams, respectively. A comparison based on a bending strength performance index showed that the properties of the ceramic–precursor‐derived foams compared favorably with those of steel foams fabricated by other techniques.