Metal foams are lightweight porous materials made from metals like aluminum, iron, copper, and alloys with gas-filled pores that provide high porosity between 75-95%. They have applications as lightweight structures, filters, heat exchangers, sound absorbers, and electrodes due to their properties of being stiff yet light, having a similar coefficient of thermal expansion as metals, and reduced thermal conductivity. Metal foams come in open-cell and closed-cell varieties and are manufactured by companies such as ERG Aerospace and Metal Foam Korea.

1. Metal Foam

2. Characteristics
 Made from Al, Fe, Cu, Ag, Ti, Alloy
 Gas-filled pores
 Very high porosity (75-95% void spaces)
 Light and stiff (Strength power law density)
 Similar coefficient of thermal expansion
 Reduced conductivity
 High cost, advanced technology aerospace and
manufacturing
 Open-cell & close-cell metal foams
 Manufacturers: ERG Aerospace, Metal Foam Korea, M-
Pore, Porvair, Metafoam Cymat Corporation, Alcoa

3. An open-cell aluminum foam An open-cell brass foam water treatment disk
A large-cell closed-cell aluminum foam A small-cell closed-cell aluminum foam

4. Application
 Light-weight structures
 Biochemical implants
 Filters (high-temperature filters in Chem. Ind.)
 Heat exchanger
 Mechanical damping devices
 Sound/energy absorber
 Electrodes
 Sensors