Geometrical Description of the Internal Architecture of Aluminum Foam

Dzwigalski, Krysten, Tim Rourke, David Chew, and Nihad Dukhan

The development of a variety of processes for producing metal foam at lower cost, with yet improved properties, has increased their applications. Aluminum has emerged as the prime metal for producing foam due to its low density, high conductivities and its relatively good strength and low price. In numerous applications of metal foam, there is a critical need for characterizing the internal structure of the foam, in order to understand and correlate the effect of such structure on the fluid flow and heat and mass transport inside the foam. The porous matrix of metal foam consists of ligaments of various lengths, widths, orientation and cross-sectional areas. This web forms tortuous irregularly-shaped passages for any transport through the metal foam. Current modeling relies on some geometric idealization of the foam structure such as two-dimensional arrays of hexagonal cells and the tetrakaidecahedron shape. This paper seeks to characterize the actual three-dimensional structure and the internal architecture of open-cell aluminum foam using microscopy. Average values of key parameters such as the cell size, ligament diameter, pore size, ligament length and number of closed cells per unit area, were obtained for a considerable spectrum of commercially-available aluminum foam over a range of pore densities. The results of this paper will certainly enhance the data bank for characterizing this class of porous materials, and can be used to correlate the pressure drop, heat transfer and mechanical properties of metal foam to the internal structure of the foam.