Aerogels with gradients in density have been produced in experiments, as part of an effort to develop materials that will be used in outer space to capture particles traveling at high speeds for the STARDUST mission.
On Earth, aerogels with gradients of density could be used as lightweight materials with tailorable optical, acoustical, thermal, catalyst-support, or microelectronic-packaging properties. In addition to extremely low (and now optionally spatially varying) densities, aerogels have unique combinations of properties that make them economically competitive with other materials that would otherwise be used in the same applications.
One experimental aerogel exhibited a gradient of density from 5 to 50 mg/cm3. Depending on the intended application, the gradient of density in an aerogel component could be tailored to obtain the desired corresponding gradient in the optical or acoustical index of refraction, optical or acoustical attenuation, permittivity, thermal conductivity, or other property or properties of interest.
This work was done by Steven Jones and Peter Tsou of Caltech for NASA's Jet Propulsion Laboratory . For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Materials category. NPO-20485
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Aerogels With Gradients of Density
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Overview
The document discusses the development of aerogels with controlled gradient density profiles, a significant advancement in material science conducted by Steven Jones and Peter Tsou at NASA's Jet Propulsion Laboratory (JPL). These aerogels are designed to capture hypervelocity particles, particularly for space missions like the STAR-DUST mission, which aims to collect particles from comets and other celestial bodies.
Aerogels are known for their extremely low densities and unique physical properties, which include exceptional thermal insulation, optical clarity, and acoustic attenuation. The introduction of gradient density profiles allows for tailored properties, enabling the customization of the aerogels for specific applications. This means that the density can vary within the material, which in turn affects other properties such as the index of refraction, thermal conductivity, and dielectric constant. This capability expands the potential uses of aerogels beyond traditional applications, making them suitable for roles in insulation, optics, and electronics.
The document outlines the motivation behind this research, which was to find a suitable material for capturing high-speed particles. Initial attempts involved polymer foams, but these were found lacking in certain aspects. The transition to monolithic and then graded density aerogels proved to be more effective, leading to the production of gradient density aerogels that exhibit superior properties.
The experimental results highlighted in the document include an aerogel that demonstrated a density gradient ranging from 5 to 50 mg/cm³. This gradient can be tailored to achieve desired optical or acoustical properties, making these materials economically competitive with other options available for similar applications.
Overall, the work represents a significant step forward in the field of aerogels, showcasing the potential for creating custom materials that meet specific needs in both space exploration and various terrestrial applications. The research emphasizes the importance of innovation in material science and its implications for future technologies.
