Characteristic of Absorbing Sound in Lotus-Type Porous Magnesium

Abstract

Lotus-type porous magnesium was fabricated by unidirectional solidification of melt dissolving hydrogen in a pressurized hydrogen atmosphere, which possesses many unidirectional cylindrical pores.
The sound absorption coefficient of porous magnesium whose sample face has many open pores was measured by standing-wave method in the range up to the frequency of sound of 4 kHz.
The absorption coefficient increases with decrease of the pore size, while it increases with increase of the porosity. Moreover, the peak value with high absorption coefficient is shifted toward higher frequency of sound when the thickness of the porous magnesium sample decreases.