Al-Si closed-cell aluminum foam bare boards of 1 240 mm×1 100 mm with different densities and thicknesses wereprepared by molten body transitional foaming process.The sound reduction index(R)of Al-Si closed-cell aluminum foam bareboards was investigated experimentally under different frequencies(100-4 000 Hz).It is found that sound reduction index(R)issmall under low frequencies,large under high frequencies and is controlled by different mechanisms.The sound insulation propertybasically conforms with the monolayer board sound insulation theory.The sound reduction index(R)increases with the even growthof thickness and density,but its rising trend is tempered.The single number sound reduction indexes(RW)of specimen with thicknessof 20 cm and density of 0.51 g/cm3are 30.8 dB and 33 dB respectively,which demonstrates good sound insulation property forlightmass materials.
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