Comprehensive Study of the Interaction and Mechanism between Bistetrazole Ionic Salt and Ammonium Nitrate Explosive in Thermal Decomposition

Bistetrazole energetic ionic salts, such as dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50) and diamino 5,5′-bistetrazole-1,1′-diolate (ABTOX), are new insensitive materials and have great potential applications because of their good energy and safety performance. Prior to pure explosive preparation into PBX, the interactions between the components must be evaluated. Examination of interactions between bistetrazole ionic salt and ammonium nitrate explosive in thermal decomposition is beneficial in revealing the interactive mechanism of these two kinds of energetic materials in decomposition, as well as in the evaluation of compatibility, safety, and reliability of PBX explosive based on TKX-50, ABTOX, HMX, and RDX. Herein, the thermal decomposition behavior of TKX-50/HMX, ABTOX/HMX, TKX-50/RDX, and ABTOX/RDX is investigated. Ammonium nitrate explosives can significantly reduce the thermal decomposition peak temperature of the bistetrazole ionic salt. For example, HMX reduces the decomposition peak temperatures of the first and second stages of TKX-50 by 4 and 15 K, respectively, and ABTOX by 26 K (heating rate 5 K min–1). Utilizing HMX, the interaction mechanism between ammonium nitrate explosives and bistetrazole ionic material in thermal decomposition was investigated in detail. Changes in gas products, morphology, and molecular structure of the materials during decomposition show that TKX-50 induces HMX to HONO elimination decomposition, while ABTOX induces HMX open-loop decomposition. Furthermore, the heat generated by HMX decomposition accelerates the decomposition of TKX-50 and ABTOX. Moreover, the melting characteristics of HMX and molten product formation in the decomposition of TKX-50 and ABTOX promote the interaction between solid phase materials. Additionally, using calculation simulation, we confirmed that NH3OH+ in TKX-50 transfers hydrogen to the HMX nitro group, resulting in the HONO elimination of HMX, while the bistetrazole N-oxide anion in ABTOX and its alkaline decomposition intermediate product captures the hydrogen of the HMX main ring and causes HMX ring-opening decomposition.