Metal Foam (closed cell) & (open cell)

Metal foam is a cellular structure made up of a solid metal containing a large volume fraction of
gas-filled pores. These pores can either be sealed (closed-cell foam), or they can be an interconnected network (open-cell foam). The closed-cell foam is referred to as metal foams, while the open-cell foam is referred to simply as porous metal.

Metals that Can Be Used
The metal that is commonly used to make metal foams is aluminium. However, other  varieties of metals can be used to make the foam, such as titanium and tantalum.

Properties of Metal Foam
The key properties of metal foam are as follows:

• Ultralight material (75–95% of the volume consists of void spaces)
• Very high porosity
• High compression strengths combined with good energy absorption characteristics
• Thermal conductivity is low
• High strength

Applications
The main applications of metal foams and porous metals are listed below:

• The closed variety is used for structural applications requiring load-bearing features, and for weight-saving and impact-absorbing structures in vehicles
• The open variety is ideal for vibration and sound absorption, filtration and catalysis at high temperatures, for heat exchange and in medical devices.
• The open variety is also useful in functional applications such as filtration and damping.
• Foam metal is being used as an experimental prosthetic in animals.
• Metal foams with high strengths can act as high-capacity impact-energy absorbers.
• Automotive industry - the foams reduce the number of parts in the car frame, facilitate assembly, thereby reducing costs and improving performance.

From:  http://www.azom.com/article.aspx?ArticleID=8097#3 

Closed Cell

Closed Cell