Study on the decomposition kinetics of FOX-7 and HNF

Abstract

At TNO Prins Maurits Laboratory the characterisation and application of energetic materials is one of the main research topics. In this respect, the activities are focussed on using thermal analysis techniques such as TG/DTA and DSC. Standard DSC and TG/DTA techniques usually apply a linear temperature increase. During this gradual temperature change, the sample may pass certain phase changes related to different crystal structures, followed by a melting/decomposition of the material. In this way physicochemical properties like phase change temperatures, melting point, enthalpy of melting, decomposition temperature, etc. can be determined. By applying different heating rates, an analysis of the decomposition kinetics can be performed as well, which gives additional information on the decomposition process of the material. In this way the activation energy of the decomposition process and the 'shelf-life' of the material, when stored at a certain temperature, can be assessed. In a co-operation with the Technical University of Aachen, two relatively new and promising energetic materials were investigated: FOX-7 and HNF. FOX-7, or 1,1-diamino-2,2-dinitroethylene, is a less sensitive explosive, which could find application as a substitute of RDX (less sensitive but with preservation of performance). Hydrazinium nitroformate (HNF) is an oxidiser with potential use as a high-performance, chlorine-free ingredient in rocket propellants. The results of the TG/DTA and DSC tests, as well as the results of the analysis of the decomposition kinetics of these two materials, will be reported and discussed in this paper.