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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

Macroscopic and microscopic structures of ultralight metal foams.(a) Digital photograph of ultralight metal foams: (A) the polymer template acquired after the silver mirror reaction; (B) Ag foam; (C) Ni foam; (D) Co foam; (E) Cu foam. (b) A piece of ultralight Ni foam with the density of 7.4 mg/cm3 supported on a dandelion. (c) Low-magnification SEM image of the Ag foam. (d) Highly magnified image of a filament of the Ag foam. (e) SEM image of the Ag foam with hollow filaments. (f) The hollow filament of Ag foam. (g) XRD patterns of the Ag foam.
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f2: Macroscopic and microscopic structures of ultralight metal foams.(a) Digital photograph of ultralight metal foams: (A) the polymer template acquired after the silver mirror reaction; (B) Ag foam; (C) Ni foam; (D) Co foam; (E) Cu foam. (b) A piece of ultralight Ni foam with the density of 7.4 mg/cm3 supported on a dandelion. (c) Low-magnification SEM image of the Ag foam. (d) Highly magnified image of a filament of the Ag foam. (e) SEM image of the Ag foam with hollow filaments. (f) The hollow filament of Ag foam. (g) XRD patterns of the Ag foam.

Mentions: Figure 2a shows the digital photograph of ultralight metal foams (Ag, Ni, Co, Cu) and the polymer template acquired after the silver mirror reaction. A piece of ultralight Ni foam with the density of 7.4 mg/cm3 is shown supported on a dandelion (Fig. 2b). The polymer foam with Ag coating acquired after the silver mirror reaction was heated to 700 °C in an air atmosphere in a muffle furnace to burn away the polymer template, and then, ultralight monolithic Ag foams were obtained (Fig. 2a (B)). The porosity of this ultralight monolithic Ag foam is 99.8% (ρ = 18.7 mg/cm3, 11.8 mg in 0.63 cm3). The heating process results in an obvious decrease in volume (by roughly 50%) from the polymer foam image, as shown in Fig. 2a (A) and (B). A low-magnification SEM image of the monolithic Ag foam (Fig. 2c) shows a three-dimensional network structure consisting of uniform slender filaments. The filaments of the Ag foam became curled (Supplementary Fig. S2) during the heating process which results in a dramatic decrease in volume of the Ag foam. Figure 2d shows a highly magnified image of the morphology of a filament of the Ag foam, which is analogous to the silver sponges reported in the literature14. The filament is approximately 3 μm in diameter and is produced from the coarsening of interconnected silver particles. Energy dispersive spectrometer (EDS) analysis of the silver filament showed that only silver is present (Supplementary Fig. S3). In X-ray diffraction (XRD), strong metallic silver reflections were observed from an Ag foam specimen, and no other residual peaks were detected (Fig. 2g). It is noticed that the microstructure of the Ag foam can be tuned by altering the heating temperature. By reducing the heating temperature from 700 °C to 680 °C, hollow filaments were obtained in the Ag foam (Fig. 2e,f). The filament is tubular in structure, and many holes exist in the wall.


Ultralight metal foams.

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

Macroscopic and microscopic structures of ultralight metal foams.(a) Digital photograph of ultralight metal foams: (A) the polymer template acquired after the silver mirror reaction; (B) Ag foam; (C) Ni foam; (D) Co foam; (E) Cu foam. (b) A piece of ultralight Ni foam with the density of 7.4 mg/cm3 supported on a dandelion. (c) Low-magnification SEM image of the Ag foam. (d) Highly magnified image of a filament of the Ag foam. (e) SEM image of the Ag foam with hollow filaments. (f) The hollow filament of Ag foam. (g) XRD patterns of the Ag foam.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Macroscopic and microscopic structures of ultralight metal foams.(a) Digital photograph of ultralight metal foams: (A) the polymer template acquired after the silver mirror reaction; (B) Ag foam; (C) Ni foam; (D) Co foam; (E) Cu foam. (b) A piece of ultralight Ni foam with the density of 7.4 mg/cm3 supported on a dandelion. (c) Low-magnification SEM image of the Ag foam. (d) Highly magnified image of a filament of the Ag foam. (e) SEM image of the Ag foam with hollow filaments. (f) The hollow filament of Ag foam. (g) XRD patterns of the Ag foam.
Mentions: Figure 2a shows the digital photograph of ultralight metal foams (Ag, Ni, Co, Cu) and the polymer template acquired after the silver mirror reaction. A piece of ultralight Ni foam with the density of 7.4 mg/cm3 is shown supported on a dandelion (Fig. 2b). The polymer foam with Ag coating acquired after the silver mirror reaction was heated to 700 °C in an air atmosphere in a muffle furnace to burn away the polymer template, and then, ultralight monolithic Ag foams were obtained (Fig. 2a (B)). The porosity of this ultralight monolithic Ag foam is 99.8% (ρ = 18.7 mg/cm3, 11.8 mg in 0.63 cm3). The heating process results in an obvious decrease in volume (by roughly 50%) from the polymer foam image, as shown in Fig. 2a (A) and (B). A low-magnification SEM image of the monolithic Ag foam (Fig. 2c) shows a three-dimensional network structure consisting of uniform slender filaments. The filaments of the Ag foam became curled (Supplementary Fig. S2) during the heating process which results in a dramatic decrease in volume of the Ag foam. Figure 2d shows a highly magnified image of the morphology of a filament of the Ag foam, which is analogous to the silver sponges reported in the literature14. The filament is approximately 3 μm in diameter and is produced from the coarsening of interconnected silver particles. Energy dispersive spectrometer (EDS) analysis of the silver filament showed that only silver is present (Supplementary Fig. S3). In X-ray diffraction (XRD), strong metallic silver reflections were observed from an Ag foam specimen, and no other residual peaks were detected (Fig. 2g). It is noticed that the microstructure of the Ag foam can be tuned by altering the heating temperature. By reducing the heating temperature from 700 °C to 680 °C, hollow filaments were obtained in the Ag foam (Fig. 2e,f). The filament is tubular in structure, and many holes exist in the wall.

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