Thermally Emitting Iron Aerogel Composites
Abstract
Aerogels are a class of materials with extremely high surface area and porosity. An exothermic reaction that takes place on the hundreds of square meters/gram of aerogel surface area could result in substantial thermal emission. Here we report various air-sensitive, thermally emitting aerogels based on the exothermic reaction of iron metal to iron oxide. Aerogels containing iron, either as a component of the nanoscale aerogel structure or as a vapor-deposited coating on an aerogel substrate have been prepared and evaluated. Using the first approach, composite aerogels of iron and silica have been produced via a solution-gelation (sol-gel) route, however none of these materials produced any detectable heat when exposed to air. Using the second approach, iron was deposited on silica, carbon and resorcinol/formaldehyde (RF) aerogels by metal organic chemical vapor deposition using ferrocene and iron pentacarbonyl as iron precursors. While the silica aerogels coated with iron from iron pentacarbonyl emitted low, but detectable, amounts of heat, the most energetic materials were carbon and RF aerogels deposited with iron from iron pentacarbonyl. Oxidation of the deposited iron on both carbon and RF aerogels created enough heat to ignite the aerogel substrates. These samples burned at 600 to 700 degrees C for a duration that depended on sample size. The iron/carbon composites burn relatively cleanly, however combustion of the RF substrate results in the release of volatile organic compounds including benzene and toluene.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 29, 2000
- Accession Number
- ADA382821
Entities
People
- Celia Merzbacher
- Debra R. Rolison
- Robert Bernstein
- Zachary Homrighaus
Organizations
- United States Naval Research Laboratory