(526e) Nanocomposite Thermites with Calcium Iodate As an Oxidizer
AIChE Annual Meeting
2016
2016 AIChE Annual Meeting
Particle Technology Forum
Energetic and Reactive Materials II
Wednesday, November 16, 2016 - 1:53pm to 2:10pm
Iodine bearing reactive materials and fuel additives are being developed to inactivate aerosolized harmful microorganisms by combined thermal and chemical effects. Composite thermite powders were prepared by mechanical milling with 80 wt% of calcium iodate, Ca(IO3)2, as an oxidizer and with 20 wt % of aluminum or boron as fuels. Different milling protocols have been explored for synthesizing different materials. Morphology and particle sizes of the prepared materials were characterized using scanning electron microscopy (SEM). Aluminum containing materials formed composites with particles sized from 1 to 10 µm. After material was stored in air for two weeks, particle surface morphologies changed indicating substantial aging. In particular, smooth surface areas, indicative of formation of aluminum hydroxide, were detected under SEM. Boron containing materials produce smaller size composite particles with calcium iodate well mixed with boron. Exposure to air for two weeks caused no changes in the material morphology. Both materials were ignited as thin coatings on an electrically heated filament. The ignition temperatures of B·Ca(IO3)2 were close to 700 K, much lower than approximately 1100 K at which ignition of Al·Ca(IO3)2 was observed. Particles were also burned in the combustion products of an air-acetylene flame. Particle burn times were recorded optically and correlated with their sizes. The burn times for B·Ca(IO3)2 were longer than for Al·Ca(IO3)2. Both materials were also ignited by electro-static discharge. Al·Ca(IO3)2 composite was difficult to ignite, while B·Ca(IO3)2 composites ignited readily. Finally, the composite powders were pressed into pellets and ignited with a CO2 laser. For the same size pellets, the aluminum-based materials required more energy for ignition than boron-based materials. Two Hamamatsu R3896-03 photo-multiplier tubes were equipped with 700 and 800-nm interference filters to record the pellet combustion emission. At the same time, a high speed camera and StellarNet BW16 spectrometer were employed to observe the combustion events and obtain integrated emission spectra. Bulk burn rate for Al·Ca(IO3)2 pelletwas 0.8 g/s and it was doubled forthe pellet of B·Ca(IO3)2. Results will be discussed in this talk.