Abstract
Abstract In this study, a kind of structural gradient metal hollow spheres composites (SG-MHSCs) were fabricated using two kinds of 316L stainless steel hollow spheres with different diameters and A356 aluminum through the casting method. Then the density of the SG-MHSCs was measured by the direct measurement; the microstructure of the SG-MHSCs was characterized by the Scanning Electron Microscope. Meanwhile, the acoustic performance of MHSCs was tested by the impedance tube, and the sound absorption and insulation mechanism SG-MHSCs were discussed and analyzed.
Highlights
Metal hollow spheres composites (MHSCs) were a kind of closed-cell porous material
In order to explore the sound absorption and insulation mechanism of SG-MHSCs, we used the metal hollow spheres (MHSs) with different diameters to fabricate the SG-MHSCs, the density and microstructure of the SG-MHSCs were characterized
According to the experimental results, the sound absorption and insulation mechanism of the SG-MHSCs were analyzed, and the conclusions were as follows: (1) The density of the MHSCs-2.88, MHSCs-5.76, and the SG-MHSCs was similar and 1.74–1.76 g/cm3 when the volume fraction of MHSs in the MHSCs was 48.50%. (2) The microstructure observation showed that the MHSs and matrix occurred in an alloying reaction and formed a continuous transition layer composed by the Fe2Al7Si phases
Summary
Metal hollow spheres composites (MHSCs) were a kind of closed-cell porous material. Generally, the casting andIt was widely known that the closed-cell metal foams were mostly used in the field of sound insulation due to the closed-cell structure [22]. The sound insulation mechanism was that the sound waves entered the closedcell metal foams by the refraction and propagated, which caused the air vibration in the pores. The vibrating air rubbed against the pores wall, and the sound waves energy was converted into heat energy [23,24,25,26]. The absorption coefficient of acoustic materials was studied by analyzing the sound waves energy reflected of acoustic materials. The part of energy consumed by the materials should be considered only, when studying the sound transmission loss of materials. It was a fast and efficient way to study the sound absorption and insulation
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