Abstract:Al-Si closed-cell aluminum foam bare boards of 1 240 mm×1 100 mm with different densities and thicknesses were prepared by molten body transitional foaming process. The sound reduction index(R) of Al-Si closed-cell aluminum foam bare boards was investigated experimentally under different frequencies (100−4 000 Hz). It is found that sound reduction index(R) is small under low frequencies, large under high frequencies and is controlled by different mechanisms. The sound insulation property basically conforms with the monolayer board sound insulation theory. The sound reduction index(R) increases with the even growth of thickness and density, but its rising trend is tempered. The single number sound reduction indexes(RW) of specimen with thickness of 20 cm and density of 0.51 g/cm3 are 30.8 dB and 33 dB respectively, which demonstrates good sound insulation property for lightmass materials.

Key words: Al-Si closed-cell aluminum foam; bare board; sound reduction index(R); density; thickness