Thermal decomposition of energetic materials 31—Fast thermolysis of ammonium nitrate, ethylenediammonium dinitrate and hydrazinium nitrate and the relationship to the burning rate

Abstract

High-heating-rate (≤100°C/s) thermolysis studies at various pressures (1–1000 psi) are described for NH 4NO 3(AN), [NH 3CH 2CH 2NH 3](NO 3) 2(EDDN), [NH 2NH 3](NO 3)(HN), 50 50 AN/EDDN, and 67 33 HAN/HN (HAN = hydroxylammonium nitrate) by using the rapid-scan FTIR/thermal profiling technique. For all of the solid materials, melting is detected in advance of decomposition. HNO 3 is the first gas decomposition product detected, and undoubtedly is formed by endothermic proton transfer. Pressures above atmospheric are required to produce exothermic events, probably because the gas decomposition products are able to build around the condensed phase to the critical concentration needed for ignition. HN 3 is a significant decomposition product of HN and mixtures containign HN, which may contribute to the high impact sensitivity of the material. For all of the nitrate salts and mixtures investigated, AN is found to be a recombination product during thermal decomposition. This fact may contribute to the similarity of the burning rates of aluminized propellants made from these materials.