Influence of Composition and Pressure on the Reaction Behaviour of Ternary Thermite Mixtures Containing AL/MOO3/WO3

Thermites usually are used when high heat release is needed. To adapt the reaction rate to an intended effect ternary thermite composition can be used. In most pyrotechnic applications the reaction takes place under confined conditions under changing pressure. But for a better understanding of the influence of pressure on thermite reaction isobaric investigations are important. In this work in progress study, the reaction rate of stoichiometric ternary thermite mixtures of aluminium with MoO3 and WO3 with different ratios of oxide fractions are investigated as loose bulk in test tubes at 0.1 to 10 MPa in a window bomb. The reaction rate is characterized as the propagation velocity of the flame front. For all mixtures, a maximum reaction rate was measured between 0.2 and 0.5 MPa, which is only slightly higher than at atmospheric pressure. With higher pressure, the reaction rate decreases by an order of magnitude. The binary mixture of Al and WO3 is quite slow, Al/MoO3 burns much faster. The reaction rates of the ternary mixtures change between these both limits continuously. But this difference of the total variation of the reaction rates decreases drastically with increasing pressure.