Fabrication Method for Closed-cell Aluminium Foam with Improved Sound Absorption Ability

The paper presents new method for production of closed-cell Al foams of improved sound absorbing ability with no machining operations. Opening the closed-cell structure of solid foamed Al is provided by micrometer sized cracks lengthways the eutectic domains created by finish heat treatment that includes heating below the solidus temperature followed by water quenching. The presence of through cracks provides for interconnection of the cells, making them like Helmholtz micro-perforated resonators and ensuring the increase by 15% of sound absorption coefficient. Processing parameters of foaming and followed heat treatment required for transformation of closed cells into micro-perforated resonators are discussed and specified.