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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

Microscopic structures of ultralight Ni/Ag foams.(a) Low-magnification image of the Ni/Ag foam. (b) SEM image of a filament of the Ni/Ag foam. (c) and (d) the microscopic structures of the film of the ultralight Ni/Ag foam. (e) XRD patterns of the Ni/Ag foam.
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f3: Microscopic structures of ultralight Ni/Ag foams.(a) Low-magnification image of the Ni/Ag foam. (b) SEM image of a filament of the Ni/Ag foam. (c) and (d) the microscopic structures of the film of the ultralight Ni/Ag foam. (e) XRD patterns of the Ni/Ag foam.

Mentions: As presented above, different Ag foam microstructures were obtained as the heating temperature was changed. Since the polymer used in our study only completely decomposed at a temperature >680 °C, it was not possible to use a lower temperature. The microstructure of the Ag foam should be similar with the original polymer foam template (Supplementary Fig. S1). The initial silver film is about 200–300 nm in thickness (Fig. 3c). The wall thickness of the Ag tube should be 200–300 nm. Corresponding SEM studies (Fig. 2e,f) indicated that the change in morphology was associated with increased consolidation of the framework due to coarsening of the interconnected silver particles, growth of sintering necks, and reduction in size of the void spaces. When the foam was heat-treated at 680 °C in the muffle furnace to burn away the polymer template, the particle size of the silver film which is 100–200 nm obtained by the silver mirror reaction increased to 500–2000 nm (Supplementary Fig. S4). Many holes on the silver film were produced due to decomposition and gasification of the polymer substrate at high temperatures. The coarsened silver film composed of a tubular structure can stand as a monolithic structure on its own, in isolation from the template. As the heating temperature was increased to 700 °C, the particles of the silver film continuously coarsened. The tubular structure of the silver film transformed to a solid structure in order to reduce the surface energy, with the particles growing to 2–3 μm. The filaments of the Ag foam became curled during the heating process (Supplementary Fig. S2). This was most prominent for samples prepared at 750 °C. The filaments of the Ag foam became so soft and flexible that they could not bear their own weight. The shape of the foam became irregular and the dimensions decreased greatly.


Ultralight metal foams.

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

Microscopic structures of ultralight Ni/Ag foams.(a) Low-magnification image of the Ni/Ag foam. (b) SEM image of a filament of the Ni/Ag foam. (c) and (d) the microscopic structures of the film of the ultralight Ni/Ag foam. (e) XRD patterns of the Ni/Ag foam.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Microscopic structures of ultralight Ni/Ag foams.(a) Low-magnification image of the Ni/Ag foam. (b) SEM image of a filament of the Ni/Ag foam. (c) and (d) the microscopic structures of the film of the ultralight Ni/Ag foam. (e) XRD patterns of the Ni/Ag foam.
Mentions: As presented above, different Ag foam microstructures were obtained as the heating temperature was changed. Since the polymer used in our study only completely decomposed at a temperature >680 °C, it was not possible to use a lower temperature. The microstructure of the Ag foam should be similar with the original polymer foam template (Supplementary Fig. S1). The initial silver film is about 200–300 nm in thickness (Fig. 3c). The wall thickness of the Ag tube should be 200–300 nm. Corresponding SEM studies (Fig. 2e,f) indicated that the change in morphology was associated with increased consolidation of the framework due to coarsening of the interconnected silver particles, growth of sintering necks, and reduction in size of the void spaces. When the foam was heat-treated at 680 °C in the muffle furnace to burn away the polymer template, the particle size of the silver film which is 100–200 nm obtained by the silver mirror reaction increased to 500–2000 nm (Supplementary Fig. S4). Many holes on the silver film were produced due to decomposition and gasification of the polymer substrate at high temperatures. The coarsened silver film composed of a tubular structure can stand as a monolithic structure on its own, in isolation from the template. As the heating temperature was increased to 700 °C, the particles of the silver film continuously coarsened. The tubular structure of the silver film transformed to a solid structure in order to reduce the surface energy, with the particles growing to 2–3 μm. The filaments of the Ag foam became curled during the heating process (Supplementary Fig. S2). This was most prominent for samples prepared at 750 °C. The filaments of the Ag foam became so soft and flexible that they could not bear their own weight. The shape of the foam became irregular and the dimensions decreased greatly.

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