Experimental and theoretical comparison of a systematic variety of thermite compositions

Thermites enable the release of large amounts of heat accompanied with low gas production. This offers a high potential to divers pyrotechnic applications like incendiaries, flares, igniter or delay compositions. Thermite type reactions are characterized by a redox reaction of a metal with a metallic oxide. Nearly all solid metals or even half-metals may be used for this type of reaction. So a comprehensive thermodynamic Ellingham-analysis is performed calculating the heat of reaction of more than 10000 possible thermite type reactions. From this, micro-sized particles of Al, Mg, B, Si, Ti and Zr in a matrix-combination with 18 promising oxides were selected for experimental investigation in order to compare reaction velocity (characterized as progression rate) and reaction temperature in nitrogen and air. The latter one aims in additional performance using post-combustion of the produced metal with atmospheric oxygen. Depending on the combined substances progression rate varied from 2 mm/s to 20 m/s. Measured temperatures in nitrogen ranked from 1200 to 3000 K, which were significantly low as the combustion temperatures in air ranking from 1550 to 4500 K.