A STUDY ON SOUND-ABSORPTION ABILITY OF CLOSED-CELL ALUMINIUM FOAMS

Metallic foams have gained popularity in industrial applications and research due to their unique mechanical properties combined with light weight, vibroacoustic damping and high-temperature resistance. Generally, closed-cell foams have poor sound absorption properties due to their closed cellular structure when compared to open-cell foams. This paper investigates a new composite closed-cell foam for its acoustic properties. The new closed-cell aluminium fly-ash foam was made with liquid processing, using calcium carbonate (CaCO3) as the blowing agent. The effects of the fly-ash content on the cell morphology and mechanical properties were analyzed. Acoustic studies were conducted on the prepared closed-cell foam using the impedance tube method. Samples were prepared in different ways to determine the effects of the changing parameters. The results of quasi-static compression and microstructural analyses of two different combinations of the foam revealed small pore sizes with varying relative densities and compressive strengths. It is evident from the acoustic studies that the foams are capable of improved sound absorption of medium and high frequencies.