Although functional materials are not a new application for powder metallurgy (PM), renewed emphasis and constant development are creating new possibilities. For instance, the European Powder Metallurgy Association (EPMA) just launched the Functional Materials Sectoral Group, known as EuroFM Group, at the end of 2018. As noted in their press release, the purpose of focusing on functional materials is to, “…keep PM at the cutting edge of industrial applications.” The term “functional” can be broadly applied to any application where a material’s physical properties are integral to the application. This includes electrical or thermal conductivity, catalytic activity, magnetic response, and many other non-structural roles. That is not to say that these materials are not suitable for structural applications. To the contrary, they can serve in both respects, if designed appropriately.
In functional applications where surface area is critical, such as electrodes or catalysis, porous materials are a proven choice. In PM, particle characteristics will dictate the amount and morphology of pores and surface roughness (i.e., surface area). A process for creating additional microscale porosity in metal powder, recently described in this journal, has been studied in various aspects in copper. Through that work, it has been demonstrated that pore formation and characteristics can be controlled through a combination of powder preparation and heat treatment. The general mechanism of pore formation requires two steps: (1) inclusion of oxide particles within the copper powder, and (2) the reduction of those oxides to create porosity. The unique benefit of this process is that the powder can be identical in most respects to other metallic powders (size, shape, etc.), so it can be easily integrated into current powder metal processes. Successful use of this process has now also been reported in nickel and Monel (i.e., Ni alloy 400, ∼70% Ni, 30% Cu), which opens up a broad range of functional applications.
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Although functional materials are not a new application for powder metallurgy (PM), renewed emphasis and constant development are creating new possibilities. For instance, the European Powder Metallurgy Association (EPMA) just launched the Functional Materials Sectoral Group, known as EuroFM Group, at the end of 2018. As noted in their press release, the purpose of focusing on functional materials is to, “…keep PM at the cutting edge of industrial applications.” The term “functional” can be broadly applied to any application where a material’s physical properties are integral to the application. This includes electrical or thermal conductivity, catalytic activity, magnetic response, and many other non-structural roles. That is not to say that these materials are not suitable for structural applications. To the contrary, they can serve in both respects, if designed appropriately.
In functional applications where surface area is critical, such as electrodes or catalysis, porous materials are a proven choice. In PM, particle characteristics will dictate the amount and morphology of pores and surface roughness (i.e., surface area). A process for creating additional microscale porosity in metal powder, recently described in this journal, has been studied in various aspects in copper. Through that work, it has been demonstrated that pore formation and characteristics can be controlled through a combination of powder preparation and heat treatment. The general mechanism of pore formation requires two steps: (1) inclusion of oxide particles within the copper powder, and (2) the reduction of those oxides to create porosity. The unique benefit of this process is that the powder can be identical in most respects to other metallic powders (size, shape, etc.), so it can be easily integrated into current powder metal processes. Successful use of this process has now also been reported in nickel and Monel (i.e., Ni alloy 400, ∼70% Ni, 30% Cu), which opens up a broad range of functional applications.
