Structural Characteristics of Aluminum Foam Materials

Aluminum foam is composed of an aluminum metal matrix material and pores. The structural parameters of aluminum foam include pore diameter, porosity or relative density, pore roundness, and specific surface area. The connectivity between the pore structures can be classified as open-cell aluminum foam and closed-cell aluminum foam, The pore distribution of aluminum foam is usually random, but specific processes can achieve an orderly distribution. The shape of the pores can be a closed-cell structure, an open-cell structure, or a mixture of both. The pores of open-cell aluminum foam are connected, while the pores of closed-cell aluminum foam are independent and separated from each other so that aluminum foam can be regarded as a composite material of two phases: the aluminum matrix and the pores. Closed-cell structure: the pore walls are completely closed to each other, and the gas is wrapped in the pores, which has good sound and heat insulation effects and is commonly used in energy absorption, anti-collision, and other fields. Open-cell structure: the pore walls are connected, with good air permeability and fluid conductivity, suitable for filtration, heat dissipation, and other scenarios. Since the structural parameters of aluminum foam directly determine the performance of aluminum foam, in practical applications, aluminum foam materials with appropriate parameters should be selected according to different applications. Compared with traditional metal materials, aluminum foam is characterized by large pore size (pore size D = 0.2 mm to 8 mm), high porosity (porosity 63% to 90%), and low density. The skeleton structure of aluminum foam shows a three-dimensional reticular distribution, consisting of solid parts of aluminum alloy. This reticulation gives the material excellent mechanical properties, such as high specific strength and good energy absorption. The outer surface of aluminum foam is usually rough with visible pores, but the surface quality can be improved by post-treatment (e.g., coating, machining).

All in all, the structural characteristics of aluminum foam are its porosity, lightweight and high strength, and three-dimensional reticulated skeleton. These structural properties determine its wide application in the fields of acoustic and thermal insulation, energy absorption, impact resistance, filtration, and lightweight construction.

Structural characteristics of the foamed aluminum: (a) the open-celled foamed aluminum; (b) the close-celled foamed aluminum