Combustion behavior of sol-gel synthesized aluminum and tungsten trioxide

Calcined (to remove impurities) and non-calcined tungsten trioxide (WO3) aerogels as well as micron-scale and nano-scale commercial WO3 powders were mixed with nano-scale aluminum (Al) and their combustion performance in the form of combustion wave speeds was compared in loose powder and pressed pellet configurations. Results show that both the calcined and non-calcined, aerogel based mixtures outperformed the commercial based mixtures in both configurations. Combustion wave speed was also found as a function of mixture bulk density. Results show that conduction is the dominant energy transfer mechanism in pressed pellets while convection is the dominant mechanism in loose powder form. This causes material purity to be the most important factor for pressed pellets and oxidizer particle size to be the most important factor for loose powders. A preliminary aging study was conducted which showed a 7% performance reduction after 4 days of laboratory air exposure and 91-98% performance reduction after 22 months of exposure.