Thermal behavior and safety of fine TAGzT and its CMDB propellants including characterization and energy performance evaluation

A superfine microcrystalline powder of bis-(triaminoguanidinium)-5,5'-azotetrazolate (TAGzT) is prepared by the high-energy ball milling method. The microstructure, elemental composition, thermal decomposition mechanism, and sensitivity characteristics of fine TAGzT are studied by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), thermal gravimetric and mass spectrometry, and sensitivity tests. The results show that fine TAGzT consists of irregular granules with a rough surface and contains only C and H elements. TAGzT begins to decompose at about 199$^{\circ}$C, with the thermal decomposition products being mainly CH$_4$, NH$_3$, and H$_2$O. The sensitivity test shows that fine TAGzT has good stability. As calculated by the EXPLO-5 software, fine TAGzT has better energy performance than HMX. Composite modified double base propellant (CMDB) samples containing fine TAGzT are designed and prepared. The microstructure, elemental distribution, thermal decomposition mechanism, and sensitivity characteristics of CMDB propellant samples are studied by SEM, EDS, XPS, DSC, and mechanical sensitivity tests. The results show that there are tiny bulges and cracks on the sample surface, and the mass ratio of the components is consistent before and after preparation. With an increase in the fine TAGzT content in the propellant, the thermal decomposition peak temperature moves backward, while $E_{\mathrm{K}}$ increases first and then decreases. The $H_{50}$ value of the CMDB propellant decreases with an increase in the fine TAGzT content. The CMDB propellants are calculated using the CproPEP software, where fine TAGzT is added to the propellant formulation to have higher values of $I_{sp}$ and $C^*$ than those of HMX and lower values of $T_c$ and $M_c$. By introducing fine TAGzT into the CMDB propellant, higher energy and better safety can be obtained