Appliance Design - March 2009 - (Page 24)

METALS Foamy Future Metallic foams offer new design opportunities. Applications for metal foam are wide ranging, including in the design of this lamp. Photo: M-pore. by larry adams 24 applianceDESIGN March 2009 he term metal foam is self-evident as a description; less obvious is the reason for making it. As the name suggests, metal foam is metal material that has been created with a porous, cellular structure, making it sort of a metallic sponge. The point of making such a material is to provide designers with the characteristic benefits of metal, such as strength, rigidity, thermal conductivity, and electromagnetic shielding, with the uncharacteristic benefits of lighter weight and increased surface area. Only about a dozen companies around the world produce the material, which is now being used in a range of applications such as medical implants, burners, filters, electrodes, catalysts, and heat exchangers. The foams have a cellular structure that contains a large amount of pores. They can be made out of just about any metal, but the vast majority of such foam is aluminum. Nickel, however, is a popular material for nickel-metal-hydride (NiMh) and nickelcadmium (NiCd) batteries. Other materials are selected for various properties such as corrosion resistance, high-temperature T resistance, and shape-memory capabilities (see Sidebar). They are light, typically between 5 percent and 25 percent of the density of the metal from which they are made. In fact, some metal foam materials have densities that are one tenth that of water. They typically retain many of the physical properties of their base material. Thomas Hipke of the Germany-based Fraunhofer Institute, which is a leading metal foam research organization, says that metal foams can be selected by the attainable density, desired strength, modulus of elasticity, and other properties, and can be adjusted to the targeted application. There are two general classes of metal foams: those with open pores, which are known as open-cell foams; and those with closed pores, which are known as closed-cell foams. Both open-cell and closed-cell metal foams are filled with voids that reduce the weight of material in relation to volume. The open cells are connected, allowing a path for migration, whereas closed cells do not connect. So closed cell foam does not provide access or a migration path for gases and liqwww.applianceDESIGN.com http://www.appliancedesign.com

Table of Contents Feed for the Digital Edition of Appliance Design - March 2009

Appliance Design - March 2009 Contents Editorial Shipments/Forecasts News Watch Transmitting Power Wirelessly Promises to Reduce the Ever-Growing Tangle of Cords and Cables Found in the Modern Home. There Are Different Technological Approaches for Achieving this Goal, and Some Are Already on the Market. Electrochemical Capacitors Can Provide an Extra Peak-Power Boost in Battery-Operated Appliances, Allowing Product Designs to Have Smaller Battery Packs. Metallic Foams Put the Properties of Metals into Lightweight Packages. Applications for this Emerging Technology Include Gas Burners, Heat Exchangers, and Electronics Housings. Hall-Effect Switches Are Compact and Provide a High Degree of Reliability and Durability as They Virtually Eliminate Mechanical Wear, Shock, and Contact Oxidation. Blowing Agents for Polyurethane Foam Insulation Face Increased Scrutiny Due to Global Warming Concerns, but Alternatives with Lower GWP Values May Provide Solutions to Meet These Challenges. Design Marts Association Report: AHAM Advertisers' Index

Appliance Design - March 2009

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