Gradient-structural optimization of metal fiber porous materials for sound absorption

Metal fiber porous material with full inter-connected pore structure, is a kind of attractive sound-absorbing material sintered by powder metallurgy process. In order to improve the sound absorption performance, the stainless steel fibers with different diameters were used to fabricate porous sound-absorbing materials with gradient pore structures in this paper. Two or three layers of sintered fiber porous plats with different pore structures were superposed in a certain sequence and then sintered to gradient porous materials. The effects of gradient pore structure on the sound absorption performance were also investigated. The results show that the gradient porous structure can effectively improve the sound absorption performance, and the direction and quantity of the pore gradient interface also exhibit remarkable effects on the sound absorption performance. The sound waves repeatedly reflect in the porous media between the gradient interfaces, which contributes to sound absorption improvement.