Series of diffraction patterns were measured with dry powdered ammonium nitrate from 50 – 60°C on heating and from 50 – 40°C on cooling. The variation of lattice constants allows to observe the transition. On heating the phase transition IV/II occurs between 52 and 56°C. In this temperature interval both phases are existent. On cooling, simultaneous transitions II/IV and II/V occur with phase V slowly transforming into phase IV.
The 4 phases of HMX and its transitions were investigated using X-ray diffraction. The phases were heated stepwise in a temperature range from 170 K to 510 K, measuring a diffraction pattern after each step.
The thermal expansion of the different phases and the volume changes during the phase transitions were obtained. Anomalies and strongly anisotropic expansions were observed with β- and γ-HMX.
The highest thermal expansion was found with γ-HMX, followed by δ-, β- and α-HMX. The highest volume change was observed with the β → δ transition, followed by the α → δ and the γ → δ transition.
Using numerical modelling, we studied the formation and propagation of a cloud of
fine-dispersed aluminum particles generated by a special unit under the action of high-temperature
combustion products of a solid propellant gas generator, as well as the ignition conditions of these
particles. The results of numerical modelling show that the dynamic characteristics of the cloud of
particles and their ignition substantially depend on the temperature of gas generator combustion products,
particle sizes, and the energy characteristics of the generator itself. The results obtained are in a
qualitative agreement with experiments carried out at the Fraunhofer Institute for Chemical Technology
(Pfinztal, Germany) .