Activation energy of tantalum-tungsten oxide thermite reactions

The activation energy of a sol-gel (SG) derived tantalum-tungsten oxide thermite composite was determined using the Kissinger isoconversion method. The SG derived powder was consolidated using the high-pressure spark plasma sintering (HPSPS) technique at 300 and 400 degrees C. The ignition temperatures were investigated under high heating rates (500-2000 degrees C min(-1)). Such heating rates were required in order to ignite the thermite composite. Samples consolidated at 300 degrees C exhibit an abrupt change in temperature response prior to the main ignition temperature. This change in temperature response is attributed to the crystallization of the amorphous WO(3) in the SG derived Ta-WO(3) thermite composite and not to a pre-ignition reaction between the constituents. Ignition temperatures for the Ta-WO(3) thermite ranged from approximately 465 to 670 degrees C. The activation energies of the SG derived Ta-WO(3) thermite composite consolidated at 300 and 400 degrees C were determined to be 38 +/- 2 kJ mol(-1) and 57 +/- 2 kJ mol(-1), respectively. (C) 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.