Insights into thermal behavior and gas evolution characteristics of ZnCP and CdCP by TG-FTIR-GC/MS analysis

Abstract

As newly developed primary explosives, zinc carbohydrazide perchlorate (ZnCP) and cadmium carbohydrazide perchlorate (CdCP) exhibit excellent performances. However, their inherent thermal characteristics and mechanisms are rarely reported, seriously hindering their further applications. Therefore, an effective thermal analysis method is necessary to better evaluate their thermal properties. Based on this, this study aimed to investigate the thermal behavior and gas evolution characteristics of ZnCP and CdCP by a novel thermogravimetric analysis, fourier transform infrared spectroscopy and gas chromatography/mass spectrometry (TG-FTIR-GC/MS) technique. Consequently, the thermogravimetric-derivative weight loss (TG-DTG) curves indicated that ZnCP and CdCP had three mass-loss stages. Kinetic parameters were calculated using Flynn-Wall-Ozawa (FWO) method. The results showed that the average activation energy of ZnCP was higher than that of CdCP. Moreover, the evolved gases were monitored online by FTIR and GC/MS. The results illustrated that the main gaseous products evolved were H2O, CO2, CO, HNCO, HCN, N2O, N2 and NH3, respectively. Finally, we also proposed a possible decomposition pathway of transition metal carbohydrazide perchlorates. In a word, this study provides sufficient evidences for studying thermal behavior and mechanisms of ZnCP and CdCP. Meanwhile, it also provides a promising thermal analysis technique for transition metal carbohydrazide perchlorates in aerospace, military and civilian applications.