Metal Foams

Metal Foams List

Metal foam is a kind of porous metal material, which forms a three-dimensional network structure in the metal matrix. Because there are many pores in metal foams, the size, number, uniformity, connectivity and sealing of the pores will affect the performances. The parameters closely related to the properties of metal foams include pore size, total porosity, effective porosity, density and specific surface area. As new materials, metal foams have both metallic properties and some special physical properties of non-metallic materials, which has attracted more and more attentions.

Figure 1. An example of metal foam.

Applications:

• Filtration material field: By using the transmittance properties of metal foams, they can be used as an important material for the preparation of filter. Compared with traditional porous metals, metal foams have the characteristics of large pore size and high porosity, which is suitable to be used as filtration materials. Moreover, the filter made by metal foam has a wide range of applications, including liquid filter, gas filter and the others.
• Noise reduction material field: Metal foams have excellent sound-absorbing property, which can be applied as noise reduction materials. As noise reduction materials, metal foams can be used in steam power plants, pneumatic tools, cars and the others.
• Insulation materials field: With the advantages of large specific surface area, metal foams can be used as insulation materials and the performances of metal foams are excellent.
• The other: Metal foams can also be used in the construction industry, such as building interior and exterior decorations, curtain walls, interior walls and the others. With good fire resistance, metal foams can be used as refractories in construction field. In addition, with the unique structure, metal foams can be used as catalyst carriers and also can be also be used as a porous electrode.

Classification:

According to the type of metal matrix, metal foams can be divided into aluminum foam, magnesium foam, titanium foam, copper foam, steel foam, lead foam, nickel foam, silver foam and the others.

Production processes:

According to the characteristics of technology, the preparation methods of metal foams can be divided into sintering method, electroplating method, pressure casting method and the others.

• Sintering method: Sintering method uses metal particles or fibers as raw materials. After forming and sintering process, metal foams can be obtained.
• Electroplating method: In this method, special polymer materials with three-dimensional network structure are used as the skeleton, and various metals are electroplated on them. After removing the internal polymer material by calcining, metal foams can be obtained.
• Pressure casting method: Metal foams can be prepared by two steps. Particles are firstly filled in the mold, and then the liquid metal is pressed into the gap of the particles by the pressure casting method.

Figure 2. A pressure casting system for production of metal foam.

• The others: In addition to the methods mentioned above, there are many other production methods for metal foams including eutectic solidification, foaming method and the others.

References

1. Alhusseny A N M, Nasser A G, Al-Zurf N M J. High-Porosity Metal Foams: Potentials, Applications, and Formulations[M]/ Porosity - Process, Technologies and Applications. 2018.
2. Ahmet Güner, Mustafa Merih Arıkan and Mehmet Nebioglu, New Approaches to Aluminum Integral Foam Production with Casting Methods[J]/ Metals, 2015, 5, 1553-1565.