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Ultralight metal foams.

Jiang B, He C, Zhao N, Nash P, Shi C, Wang Z - Sci Rep (2015)

Bottom Line: These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating.We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method.The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P.R. China.

ABSTRACT
Ultralight (<10 mg/cm3) cellular materials are desirable for thermal insulation; battery electrodes; catalyst supports; and acoustic, vibration, or shock energy damping. However, most of these ultralight materials, especially ultralight metal foams, are fabricated using either expensive materials or complicated procedures, which greatly limit their large-scale production and practical applications. Here we report a simple and versatile method to obtain ultralight monolithic metal foams. These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating. We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method. The resultant ultralight monolithic metal foams have remarkably low densities down to 7.4 mg/cm3 or 99.9% porosity. The metal foams have a long flat stress-train curve in compression tests and the densification strain εD of the Ni/Ag foam with a porosity of 99.8% can reach 82%. The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory.

No MeSH data available.


Related in: MedlinePlus

Compression test results of the ultralight metal foams.(a) Stress-strain curves of Ni/Ag foams with different densities. (b) Plateau stress of metal foams at low relative density.
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f4: Compression test results of the ultralight metal foams.(a) Stress-strain curves of Ni/Ag foams with different densities. (b) Plateau stress of metal foams at low relative density.

Mentions: The compression test results of the ultralight metal foams are shown in Fig. 4. The present Ni/Ag foam shows a similar stress–strain behavior compared with the other metallic foams1516, characterized by three distinct regions, i.e. linear elastic deformation, collapse plateau and densification region (Fig. 4a). Ideal energy absorbers have a long flat stress-train curve. The absorber collapses plastically at a constant nominal stress, called the plateau stress, σpl, up to a limiting nominal strain, εD. Energy absorbers for packaging and protection are chosen so that the plateau stress is just below that which will cause damage to the packaged object. The best choice is then the one which has the longest plateau, and therefore absorbs the most energy before reaching εD. The area under the curve, roughly σplεD, measures the energy the foam can absorb, up to the end of the plateau. Foams which have a long flat stress-strain curve perform well in this function. Hollow tubes, shells, and metal honeycombs have the appropriate type of stress-strain curves17. All the Ni/Ag and Ni/Co foams have hollow tubes, so the densification strain εD of the Ni/Ag foam with the porosity of 99.8% (density 15.8 mg/cm3) can reach 82%. The relatively brittle nature of the electroless nickel thin film result in the collapse plateau being a serrated curve and the Ni/Ag foam sample became powders after the compression test. The energy per unit volume absorbed by the foam up to densification is 1.45 mJ/cm3. A stress-strain curve of a Ni/Ag foam with a higher density (25.0 mg/cm3) is also shown in Fig. 4a. With increasing density of the foam, the plateau stress σpl increased and the densification strain εD decreased. The energy per unit volume absorbed by this foam is 3.29 mJ/cm3.


Ultralight metal foams.

Jiang B, He C, Zhao N, Nash P, Shi C, Wang Z - Sci Rep (2015)

Compression test results of the ultralight metal foams.(a) Stress-strain curves of Ni/Ag foams with different densities. (b) Plateau stress of metal foams at low relative density.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562267&req=5

f4: Compression test results of the ultralight metal foams.(a) Stress-strain curves of Ni/Ag foams with different densities. (b) Plateau stress of metal foams at low relative density.
Mentions: The compression test results of the ultralight metal foams are shown in Fig. 4. The present Ni/Ag foam shows a similar stress–strain behavior compared with the other metallic foams1516, characterized by three distinct regions, i.e. linear elastic deformation, collapse plateau and densification region (Fig. 4a). Ideal energy absorbers have a long flat stress-train curve. The absorber collapses plastically at a constant nominal stress, called the plateau stress, σpl, up to a limiting nominal strain, εD. Energy absorbers for packaging and protection are chosen so that the plateau stress is just below that which will cause damage to the packaged object. The best choice is then the one which has the longest plateau, and therefore absorbs the most energy before reaching εD. The area under the curve, roughly σplεD, measures the energy the foam can absorb, up to the end of the plateau. Foams which have a long flat stress-strain curve perform well in this function. Hollow tubes, shells, and metal honeycombs have the appropriate type of stress-strain curves17. All the Ni/Ag and Ni/Co foams have hollow tubes, so the densification strain εD of the Ni/Ag foam with the porosity of 99.8% (density 15.8 mg/cm3) can reach 82%. The relatively brittle nature of the electroless nickel thin film result in the collapse plateau being a serrated curve and the Ni/Ag foam sample became powders after the compression test. The energy per unit volume absorbed by the foam up to densification is 1.45 mJ/cm3. A stress-strain curve of a Ni/Ag foam with a higher density (25.0 mg/cm3) is also shown in Fig. 4a. With increasing density of the foam, the plateau stress σpl increased and the densification strain εD decreased. The energy per unit volume absorbed by this foam is 3.29 mJ/cm3.

Bottom Line: These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating.We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method.The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory.

View Article: PubMed Central - PubMed

Affiliation: School of Materials Science and Engineering, Tianjin University, Tianjin 300072, P.R. China.

ABSTRACT
Ultralight (<10 mg/cm3) cellular materials are desirable for thermal insulation; battery electrodes; catalyst supports; and acoustic, vibration, or shock energy damping. However, most of these ultralight materials, especially ultralight metal foams, are fabricated using either expensive materials or complicated procedures, which greatly limit their large-scale production and practical applications. Here we report a simple and versatile method to obtain ultralight monolithic metal foams. These materials are fabricated with a low-cost polymeric template and the method is based on the traditional silver mirror reaction and electroless plating. We have produced ultralight monolithic metal foams, such as silver, nickel, cobalt, and copper via this method. The resultant ultralight monolithic metal foams have remarkably low densities down to 7.4 mg/cm3 or 99.9% porosity. The metal foams have a long flat stress-train curve in compression tests and the densification strain εD of the Ni/Ag foam with a porosity of 99.8% can reach 82%. The plateau stress σpl was measured and found to be in agreement with the value predicted by the cellular solids theory.

No MeSH data available.


Related in: MedlinePlus