Ultralow-density materials: from aerogels to microlattices

Article By:

Jacobsen, A. J. Sensors and Materials Laboratory, HRL Laboratories, LLC, Malibu, California.

Schaedler, T. A. Sensors and Materials Laboratory, HRL Laboratories, LLC, Malibu, California.

Carter, W. B. Sensors and Materials Laboratory, HRL Laboratories, LLC, Malibu, California.

Last reviewed:2013

DOI:https://doi.org/10.1036/1097-8542.YB130104

Over the past several decades, the need to increase the fuel efficiency of automotive and aerospace vehicles has driven the development of new lightweight materials. Among other innovations, this need has led to the emergence of a variety of new low-density porous materials. Whereas solid materials are limited to densities greater than approximately 1 g/cm³, materials that include significant porosity, termed porous or cellular materials, can exhibit one-tenth that density, or even lower. Examples include manufactured cellular materials (for example, polymer foams and honeycombs) and naturally occurring cellular materials (for example, wood). Cellular materials are commonly used in applications that take advantage of their low density and unique properties. In addition to vehicle applications, cellular materials are commonly used for packaging materials, padding and other sporting goods, building materials, and acoustic baffling. Most cellular materials fall in the density range of 0.01–0.3 g/cm³, and these materials are generally considered to be technologically mature. Materials with densities below 0.01 g/cm³ (10 mg/cm³), termed ultralow-density materials, are rare primarily because of the difficulties associated with forming and maintaining a stable material. Ultralow-density materials hold considerable promise to further improve the acoustic, thermal, and fuel efficiency characteristics of future vehicle systems, and as such are the focus of current research.

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