Effects of aluminum nanoparticle addition to nitromethane (NM) are studied in terms of overall mixture burning rate using an optical pressure vessel up to 14.2 MPa. Nitromethane is gelled using fumed silica (Cab-O-Sil), as well as by the nanoaluminum (nAl) particles themselves. Use of the nanoscale metallic particles slightly increases burning rates compared to larger diameter particles, however distinct increases in burning rates are found when Cab-O-Sil is removed and replaced with more energetic aluminum nanoparticles, whose high surface area allow them to act as the gellant. Burning rates of 2.34 cm/s are seen at 14.1 MPa and 12.5% aluminum loading using 38-nm particles. Using the same nAl particles, 4% aluminum and 3% Cab-O-Sil loading, burning rates of 0.88 cm/s are seen at approximately the same pressure. In both cases mixture consistencies are roughly the same. Larger, 80-nm aluminum particles were also used in conjunction with Cab-O-Sil gellant, yielding a linear burning rate of 0.65 cm/s at 14.2 MPa (4% Al-3% Cab-O-Sil). In all mixtures, burning rate pressure exponents less than the pure nitromethane case are observed with fumed silica addition, while the exponents are increased when using nAl as the gellant.
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