• Aluminum foam specimens made from reused beverage cans.

    Credit: Courtesy Technische Universität Berlin, Helmholtz-Zentrum, and the University of Nottingham

    Aluminum foam specimens made from reused beverage cans.

Metal foams, which are porous manifestations of metals such as aluminum or zinc, represent a new class of ultralight materials capable of resisting large stresses with relatively little substance. Used primarily for automotive and orthopedic applications in which strength-to-weight ratio is a primary concern, metal foams demonstrate a highly effective use of material.

Researchers at the Technische Universität Berlin, the University of Nottingham, and Helmholtz-Zentrum have recently developed an approach to making metal foams even more resourcefully—by creating them from scrap. In an article published in Advanced Engineering Materials, the scientists outline the method of making aluminum foam entirely from discarded aluminum cans. In their liquid-based process, the researchers re-melt aluminum filings—or swarf—adding TiH2 blowing agent to create the desired foamed structure. The effort has resulted in high-quality foams, surpassing past attempts that necessitated expensive or weakening additives.

The scientists' discovery suggests an expanded consideration of the second life of metals, adding a highly resource-sensitive procedure to the existing set of options for metal recycling.

Blaine Brownell, AIA, is a regularly featured columnist whose stories appear on this website each week. His views and conclusions are not necessarily those of ARCHITECT magazine nor of the American Institute of Architects.