Thermal Decomposition Characteristics and Thermal Safety of Dihydroxylammonium 5,5′-Bistetrazole-1,1′-diolate Based on Microcalorimetric Experiment and Decoupling Method

Abstract

A microcalorimeter (C600) was used to conduct dynamic heating experiments on dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate (TKX-50), and the results were compared with those of differential scanning calorimetry (DSC). The effect of mass scale on the thermal decomposition characteristics of TKX-50 was also analyzed. The thermal decomposition curves were decoupled by mathematical method, and the kinetic parameters of each step were obtained. The thermal decomposition characteristics of TKX-50 were further analyzed by thermal history and isothermal experiment, and the thermal safety parameters were calculated by thermal analysis software (AKTS). The decomposition temperature and decomposition enthalpy of TKX-50 in the microcalorimetric experiment were higher than the corresponding parameters in the DSC experiment, and the apparent activation energy was lower than the one in the DSC experiment. When the times to maximum rate under adiabatic conditions were 2.0, 4.0, 8.0, and 24.0 h, the corresponding temperatures were 198.5, 189.6, 181.0, and 168.0 °C, respectively. After decoupling, the range of exothermic peak temperature and decomposition enthalpy of the first and second stages of TKX-50 were 226.9−245.3 and 276.3−295.7 °C and 1300.7 and 727.7 J g −1 , respectively, and the apparent activation energy of the second stage was higher than that of the first stage. The thermal history reduced the decomposition temperature and the apparent activation energy of TKX-50, the safety was reduced, and this had a great influence on the thermal decomposition kinetics of TKX-50. Thermal history and isothermal experiment showed that the first stage decomposition reaction of TKX-50 has autocatalytic properties. Therefore, it should be prevented from being placed in an adiabatic environment, and it is necessary to avoid the storage of a large mass of TKX-50 and keep the heat source off the storage location in the process of industrial production and storage, so as to prevent the formation of adiabatic environments and thermal history in the interior and further reduce the risk of explosion in TKX-50.

Combining the most suitable energetic tetrazole and triazole moieties: synthesis and characterization of 5-(1-hydroxy-3-nitro-1,2,4-triazol-5-yl)-1-hydroxy-tetrazole and its nitrogen-rich ionic derivatives

“…[17][18][19][20][21][22][23] Among the most promising molecules developed with the aim of replacing RDX are the bis-hydroxylammonium derivatives of 3,3 0 -dinitro-bis-1,2,4-triazol-1,1 0 -diolate (MAD-X1) 19 and 5,5 0bistetrazol-1,1 0 -diolate (TKX-50), 18 which are attracting great attention in the international community. [24][25][26][27][28][29][30] Combination of 1-hydroxy-tetrazole and 1-hydroxy-3-nitro-1,2,4-triazole yields the hybrid molecule 1-hydroxy-3-nitro-(1,2,4-triazol-5-yl)-1-hydroxy-tetrazole (1) with the aim to combine the positive properties of the fundamental symmetric bis-heterocycles in a new asymmetric molecule: preferrable the high heat of formation of 1,1 0 -dihydroxy-5,5 0 -bistetrazole (A) with the high density and insensitivity toward external stimuli of 1,1 0 -dihydroxy-3,3 0 -dinitro-bis-1,2,4-triazole (Fig. 2).…”

“…17–23 Among the most promising molecules developed with the aim of replacing RDX are the bis-hydroxylammonium derivatives of 3,3′-dinitro-bis-1,2,4-triazol-1,1′-diolate (MAD-X1) 19 and 5,5′-bistetrazol-1,1′-diolate (TKX-50), 18 which are attracting great attention in the international community. 24–30…”

Kinetic Modeling of Overlapping Thermal Decomposition of 2,6-Diamino-3,5-dinitropyrazine-1-oxide: Two Consecutive Autocatalytic Reactions and the Thermal Safety Assessment

“…Kinetic modeling of heterogeneous reactions that occur in thermal decomposition of energetic materials (EM) is of paramount importance for understanding their thermal behavior in deep and for the thermal safety assessment. − At present, the methodology for kinetic modeling has been developed mainly based on the assumption of single-step reactions. − However, in many EM cases, the actual kinetic behaviors are quite complicated that cannot be correctly described by simple reaction assumptions. In particular, when multistep (or multiple) heterogeneous reactions occur simultaneously, it is a challenging task to explicate the overall heterogeneous process and to clarify the detailed process of each reaction step by analyzing experimental calorimetric data from thermal analysis technology.…”

Study on the Thermal Stability of Octogen and other Energetic Materials (RDX, TNT, NQ, PBT, TDI and HTPB)

“…Due to the high mechanical sensitivity of HMX, in order to improve its safety, HMX was often mixed with many cladding materials to promote the safety of explosives, and has been widely used in the field of mixed explosives or propellants. The literatures [19–27] explored the effects of RDX, TNT, aluminized hydrides, TKX–50, CL‐20 and other substances on the thermal safety, isothermal kinetics, explosion performance, thermal decomposition mechanism, sensitivity and mechanical properties of HMX. It was found that the properties of HMX alteration significantly in their mixtures.…”