Abstract
Recently, a new class of ceramic foams with porosity levels up to 90% has
been developed as a result of the association of the gelcasting process
and aeration of the ceramic suspension. This paper presents and discusses
original results advertising sound absorbing capabilities of such foams.
The authors man- ufactured three types of alumina foams in order to
investigate three porosity levels, namely: 72, 88, and 90%. The
microstructure of foams was examined and typical dimensions and average
sizes of cells (pores) and cell-linking windows were found for each
porosity case. Then, the acoustic absorption coefficient was measured in a
wide frequency range for several samples of various thickness cut out from
the foams. The results were discussed and compared with the acoustic
absorption of typical polyurethane foams proving that the alumina foams
with high porosity of 88-90% have excellent sound absorbing properties
competitive with the quality of sound absorbing PU foams of higher
porosity.
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