Metallic foam

• Metal foam is a foam gas bubble-filled substance made out of metal, frequently aluminum. Metal foam comes in two varieties, closed-cell foam, with sealed pores, and open-cell foam, with open pores.
• Metal foams have a very high porosity, where 75-95% of the volume of the material is empty, filled by air or hydrogen.
• Metal foams retain many of the characteristics of the metal used to produce them, such as non-flammability.