“… Figure 1 “Porous metals – from nano to macro”: figures reproduced from articles in this Focus Issue illustrate the range of pore size in porous metals. (a) scanning transmission electron micrograph of a nanoporous palladium - polymer composite membranes for separations and catalysis; the nanoporous Pd was prepared by the dealloying method 20 , (b) scanning electron microscope (SEM) micrograph of nanoporous copper prepared by dealloying 21 , (c) molecular dynamics simulations of crystalline copper nanoporous structures during tensile loading 22 – scale is provided by individual atoms visible in enlarged view in circles, (d) SEM micrograph of tensile section of a carbon nanotubes reinforced aluminum foam prepared by powder metallurgy 23 (e) three-dimensionally ordered porous tungsten (inverse opals structure), prepared by a templating method 24 (f) tomographic view of porous iron created by freeze casting, ice template removal and sintering 25 (g) a 3D printed Ti-6Al-4V gyroid-structured scaffold showing diagonal shear bands from compression tests 26 (h) X-ray tomographic reconstruction of open-channel aluminum fabricated by casting and subsequent extraction of lubricated metallic wires 27 28 (i) photographs of closed-cell aluminum foams with graded density before and after a compression test 29 (j) SEM micrographs of hierarchically-porous titanium with macro-/micro-/nanopores, prepared using NaCl spacer and dealloying methods 30 . Figure 2 (a) Upward view of the Eiffel Tower in Paris, showing hierarchical structure of 18,000 iron parts (mostly struts) connected with 250 million rivets.…”
Historically, porous metals have focused on structural applications where specific stiffness and strength were optimized, using conventional casting, sintering, cutting, machining and joining techniques to create ductile and strong porous metallic structure. For such load-bearing applications, porous metals are studied and used in many sectors, e.g., transportation, architecture, and medicine (for bone-replacement implants). This special issue of the Journal of Materials Research contains articles that were accepted in response to an invitation for manuscripts.
“… Figure 1 “Porous metals – from nano to macro”: figures reproduced from articles in this Focus Issue illustrate the range of pore size in porous metals. (a) scanning transmission electron micrograph of a nanoporous palladium - polymer composite membranes for separations and catalysis; the nanoporous Pd was prepared by the dealloying method 20 , (b) scanning electron microscope (SEM) micrograph of nanoporous copper prepared by dealloying 21 , (c) molecular dynamics simulations of crystalline copper nanoporous structures during tensile loading 22 – scale is provided by individual atoms visible in enlarged view in circles, (d) SEM micrograph of tensile section of a carbon nanotubes reinforced aluminum foam prepared by powder metallurgy 23 (e) three-dimensionally ordered porous tungsten (inverse opals structure), prepared by a templating method 24 (f) tomographic view of porous iron created by freeze casting, ice template removal and sintering 25 (g) a 3D printed Ti-6Al-4V gyroid-structured scaffold showing diagonal shear bands from compression tests 26 (h) X-ray tomographic reconstruction of open-channel aluminum fabricated by casting and subsequent extraction of lubricated metallic wires 27 28 (i) photographs of closed-cell aluminum foams with graded density before and after a compression test 29 (j) SEM micrographs of hierarchically-porous titanium with macro-/micro-/nanopores, prepared using NaCl spacer and dealloying methods 30 . Figure 2 (a) Upward view of the Eiffel Tower in Paris, showing hierarchical structure of 18,000 iron parts (mostly struts) connected with 250 million rivets.…”
Historically, porous metals have focused on structural applications where specific stiffness and strength were optimized, using conventional casting, sintering, cutting, machining and joining techniques to create ductile and strong porous metallic structure. For such load-bearing applications, porous metals are studied and used in many sectors, e.g., transportation, architecture, and medicine (for bone-replacement implants). This special issue of the Journal of Materials Research contains articles that were accepted in response to an invitation for manuscripts.
“…Sublimation of the frozen solvent produces a porous structure. Initially, sublimation freezing was used to make highly porous ceramics, but recently this method has also been applied to metal suspensions such as titanium [ 7 , 8 ], Ti-Al alloy [ 9 ], iron [ 10 , 11 , 12 ], copper [ 13 , 14 , 15 , 16 ], nickel foams [ 17 , 18 , 19 ] and Cu-Ni [ 17 ].…”
The manufacturing of aluminium foams with a total porosity of 87% using the sponge replication method and a combination of the sponge replication and freezing technique is presented. Foams with different cell counts were prepared from polyurethane (PU) templates with a pore count per inch (ppi) of 10, 20 and 30; consolidation of the foams was performed in an argon atmosphere at 650 °C. The additional freezing steps resulted in lamellar pores in the foam struts. The formation of lamellar pores increased the specific surface area by a factor of 1.9 compared to foams prepared by the sponge replication method without freezing steps. The formation of additional lamellar pores improved the mechanical properties but reduced the thermal conductivity of the foams. Varying the pore cell sizes of the PU template showed that—compared to foams with dense struts—the highest increase (~7 times) in the specific surface area was observed in foams made from 10 ppi PU templates. The effect of the cell size on the mechanical and thermal properties of aluminium foams was also investigated.
“…It is also costeffective, eco-friendly, and scalable on an industrial level. However, pure Fe-foams, manufactured by FC using water [26] and camphene-based [27,28] hematite slurries, have shown significant modification of the pore structure after being subjected to several redox cycles. Authors have found a continuous reduction in the pore size due to the sintering of the Fe cell walls, which is especially critical when initial pore sizes are under 30 μm in diameter.…”
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