This paper presents an analysis of the observed combustion behavior of AN mixtures with different additives, fuels, and energetic materials. It has been determined on the basis of flame structure investigation by fine tungsten-rhenium thermocouples that the surface temperature of AN is controlled by the dissociation reaction of the salt occurring at the surface. Results obtained have indicated that the leading reaction of combustion of AN doped with additives proceeds in the condensed phase up to pressures of 20 -30 MPa. A reason for the inability of pure AN to burn is suggested and the role of additives in the combustion mechanism is discussed.

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Burning rate characteristics of the low-sensitivity explosive 5nitro-1,2,4-triazol-3-one (NTO) have been investigated in the pressure interval of 0.1 -40 MPa. The temperature distribution in the combustion wave of NTO has been measured at pressures of 0.4 -2.1 MPa. Based on burning rate and thermocouple measurements, rate constants of NTO decomposition in the molten layer at 370 -425 8C have been derived from a condensed-phase combustion model (k ¼ 8.08 · 10 13 · exp(À 19420/T) s À1 . NTO vapor pressure above the liquid (ln P ¼ À 9914.4/T þ 14.82) and solid phases (ln P ¼ À 12984.4/T þ 20.48) has been calculated. Decomposition rates of NTO at low temperatures have been defined more exactly and it has been shown that in the interval of 180 -230 8C the decomposition of solid NTO is described by the following expression: k ¼ 2.9 · 10 12 · exp(À 20680/T). Taking into account the vapor pressure data obtained, the decomposition of NTO in the gas phase at 240 -250 8C has been studied. Decomposition rate constants in the gaseous phase have been found to be comparable with rate constants in the solid state. Therefore, a partial decomposition in the gas cannot substantially increase the total rate. High values of the activation energy for solid-state decomposition of NTO are not likely to be connected with a submelting effect, because decomposition occurs at temperatures well below the melting point. It has been suggested that the abnormally high activation energy in the interval of 230 -270 8C is a consequence of peculiarities of the NTO transitional process rather than strong bonds in the molecule. In this area, the NTO molecule undergoes isomerization into the aci-form, followed by C3-N2 heterocyclic bond rupture. Both processes depend on temperature, resulting in an abnormally high value of the observed activation energy.