Sound Absorption Performance of Highly Porous Stainless Steel Foam with Reticular Structure

Abstract

There have been some previous studies on the acoustic properties of metal foams, with the main relevant works focused on the aluminum foam, but quite fewer on the metal foams of non-aluminum species. Such research, especially, has not yet been found on the stainless steel foam, of which the pore-structure related parameters and the morphology are quite different from the aluminum foam. The present work provides the investigations on the sound absorption performance of the 304 stainless steel foam and its composite structure. A sort of three-dimensional reticular stainless steel foam was successfully prepared, with the average pore size of about 1.8 mm and the porosity of about 93.7%. The sound absorption performance was investigated at 200–6300 Hz for this foam and at 2500–4000 Hz for its composite structures. The results show the whole absorption performance of the sample can be significantly improved by introducing an air gap, and further improved with introduction of both the gap and a perforated plate. It was found that when the thickness of the gap increased (from 3.5 to 17.5 mm), the resultant change of the resonance frequency of the sample could lead to a decrease of the absorption coefficient at a certain frequency range, and the total absorption efficiency could be significantly increased.