Metal foam is a solid material made from metal that is filled with pores. These voids fill up to 95% of the material in two different kinds of structures. They can be interconnected in an open-cell network or they can be sealed off from each other in a closed-cell structure. The first method injects gas into metallic melts and as the gas bubbles through the molten metal it forms a foam that is then removed using a conveyor belt and allowed to cool. The second method incorporates a chemical blowing agent, traditionally titanium hydride (TiH2), which decomposes in the melt, producing gas bubbles.
Micro-porous copper or copper foam has pores that vary in size from 300 to 600μm. The pores also make it lighter than solid copper, with a relative density of around 37%. Most importantly, the pores increase the surface area much more than that in traditional copper foam. A lost carbonate sintering process is responsible for generating the micro-pores.
The open-cell variety is ideal for vibration and sound absorption, filtration and catalysis at high temperatures, for heat exchange and in medical devices.