Hierarchical-Porous Reticulated Copper Foams by a Combination of the Schwartzwalder Process and Freezing TechniquesWednesday (07.10.2020) 16:40 - 17:00
Open-cell copper foams are attractive for energy devices, rechargeable batteries, heat exchangers, heat pumps, or fuel cells due to a combination of a high thermal/electrical conductivity and a large specific surface area. One of the manufacturing routes for open-cell metal foams is the sponge replication technique, which results in hollow struts due to the burning of the template structure.
By the freeze casting of aqueous copper dispersions highly porous lamellar architectures can be generated. Directional freeze-cast copper can be used as anodic current collector in a lithium-ion battery, for example. Despite the widespread application of freeze casting and sponge replication technique for the manufacturing of porous metal structures, a combination of sponge replication and freezing technique has never been applied for preparing highly porous metal foams with open strut pores. This novel manufacturing route can further increase the strut porosity and surface area due to the formation of lamellar pores. This is attractive for the above mentioned applications of metal foams requiring a large specific surface area and/or porous struts.
In this study, the manufacturing of hierarchical-porous open-cell copper foams by a combination of sponge replication and freezing technique using 20 ppi polyurethane foam templates and an aqueous copper dispersion is presented. The influence of the freezing procedure on the formation of the lamellar strut pores is analyzed. Furthermore, the influence of the sintering conditions (temperature and atmosphere) on the strut microstructure, the strut porosity, the compressive strength and the thermal conductivity of the copper foams is investigated. Finally, the most relevant process-structure relations are discussed.
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