Application of Foamed Metals as Functional Materials

Foam Metals are primarily applied as functional materials in the following areas:

(1) Battery Electrode Materials

Utilizing the lightweight, high specific energy, and high absorption-conversion efficiency of porous lead foam, it serves as grid material for lead-acid batteries. Active materials are uniformly coated within the pores of lead foam to create battery electrodes. The three-dimensional network structure of lead foam grids improves current distribution, reduces internal resistance, enhances reaction kinetics, and increases specific capacity and energy density. High-porosity metal foams produced via powder metallurgy have been successfully applied in fuel cells.

(2) Catalyst Carriers  

Foam metals, with their large specific surface area, mechanical resilience, and thermal conductivity, are ideal catalyst carriers. For instance, catalyst-loaded slurry is impregnated into corrosion-resistant foam metal sheets, followed by rolling and high-temperature treatment to achieve strong bonding. This design ensures catalyst stability even under repeated thermal shocks. Such carriers are used in power plant exhaust treatment for NOx reduction.

(3) Acoustic Dampers  

Metal foams, composed of metallic skeletons and pores, exhibit excellent sound absorption and vibration damping. Specific porosity levels enable targeted frequency absorption. Foam aluminum developed in Japan, the U.S., and Germany has been applied in marine, rail, and automotive systems. Porous titanium, with low density, heat resistance, and corrosion resistance, is employed in gas turbine exhaust silencers requiring durability and lightweight performance.

(4) Filtration and Separation

Foam metal filters combine fluid permeability with solid particle retention. Stainless steel and copper foams are widely used for filtering solids in liquids (e.g., fuels, polymer melts, suspensions) and gases. Applications include petroleum refining, polymer processing, and air purification.

(5) Heat Exchangers and Coolers

Copper or aluminum alloy foams, featuring high surface area and thermal conductivity, are used in heat pipes and exchangers. Their porous structure facilitates efficient heat transfer as fluids pass through. Transpiration cooling leverages foam metals’ porosity: cooling media (liquid/gas) form a stable insulating boundary layer, achieving exceptional thermal management. High-porosity copper foams are already utilized in advanced heat pipes.

(6) Flame Arrestors  

Foam metals' high thermal conductivity and surface area enable flame suppression. Installed in methane/natural gas pipelines near ignition sources, they effectively block flame propagation during combustion incidents.

(7) Biomedical Materials  

Porous titanium' s biocompatibility makes it suitable for medical applications, such as orthopedic implants (e.g., porous titanium femoral stems) and dental roots. Tungsten-chromium-nickel alloy composites are used in heart valve prostheses. Additional applications include fluid control systems (e.g., signal delayers in automation), fluid storage/transport devices, sprayers, electromagnetic shielding, water purification, and acoustic control systems.