Research scientists at the Naval Research Laboratory (NRL) have shown that using high temperatures or microwaves many agricultural wastes can be transformed into high value silicon carbide (SiC) consisting of nanostructures and nanorods in various polytypes. Billions of pounds of agricultural waste are generated every year world-wide. Rice and wheat husks, corn stalks, cobs, sorghum leaves, peanut shells and other residues are considered to have no value and are plowed into fields or incinerated. Normal incineration temperatures create environmental problems by releasing ash, CO2, and nano-particles into the air. However, these agricultural wastes have significantly high silica content in a molecular state in close proximity to hydrocarbons. Silicon carbide is used for electronic and structural devices due to its high breakdown voltage, chemical inertness, high thermal conductivity, dimensional stability, wide band gap, high radiation resistance, thermal shock resistance, and mechanical hardness. Scientists are engaged in transforming these silicon carbide nanomaterials into transparent windows and domes for applications as armor, hypersonic missiles, and thermal control of thin disc lases. Potential uses of SiC for chemical sensing, optical metamaterials, structural composites and nanoscale electronic devices are also being investigated at NRL as well as applications which promise enhancements in IR spectroscopy.

X-ray diffraction sectra of newly synthesized SiC.

Advantages

  • Hardest material next to diamond.
  • Thermally stable and radiation hard.
  • High strength, light weight.
  • Wide band gap semiconductor.
  • Optically transparent, chemically inert.
  • Low thermal expansion and high thermal conductivity.
  • Readily available, exceedingly inexpensive reagents.
  • Environmentally friendly, small carbon footprint.
  • Methods include conventional or microwave heat sources.

Application Areas

  • Abrasive and cutting tools.
  • Armored windows, hypersonic missiles and composite armor.
  • Spacecraft modules and electronics.
  • Structural material and high strength metal matrix composites.
  • High temperature and high power electronics.
  • Solar cells windows.

Licensing and Collaboration Opportunities
US Patent No. 9,051,186 and 9,120,679 are available for license to companies with commercial interest. Collaborative research and development is available under a Cooperative Research and Development Agreement (CRADA).


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