Thermal Behavior and Decomposition Mechanism of AmmoniumPerchlorate and Ammonium Nitrate in the Presence of Nanometer TriaminoguanidineNitrate

摘要

Nanometer triaminoguanidine nitrate (TAGN) with mean size of 218.7 nm was fabricated, and its structures were characterized by scanning electron microscopy, X-ray diffraction, IR, and X-ray photoelectron spectroscopy analyses. As an energetic accelerator for thermal decomposition of ammonium perchlorate (AP) and ammonium nitrate (AN), 10% nano TAGN blended with AP and AN, and samples “[90% AP + 10% (nano TAGN)]” and “[90% AN + 10% (nano TAGN)]” were obtained, respectively. Differential scanning calorimetry (DSC) analyses were employed to investigate the decomposition kinetics and thermodynamics of the samples. The results indicated that [90% AP + 10% (nano TAGN)] presented a higher activation energy (152.34 kJ mol^–1) than pure AP (117.21 kJ mol^–1) and [90% AN + 10% (nano TAGN)] possessed a lower activation energy (147.51 kJ mol^–1) than pure AN (161.40 kJ mol^–1). All activation free energies (ΔG^≠) were positive values. This means that activation of the molecules was not a spontaneous process. The decomposition peak temperature of AP decreasedfrom 478.5 °C (for pure AP) to 287.2 °C (for [90% AP + 10%(nano TAGN)]). The decomposition peak of AN also advanced via dopingwith nano TAGN. Using DSC-IR analysis, the decomposition productsof nano TAGN, pure AP, [90% AP + 10% (nano TAGN)], pure AN, and [90%AN + 10% (nano TAGN)] were investigated, and their decomposition mechanismswere proposed. The key factors, i.e., the formation of hydrazine inthe decomposition of nano TAGN, were speculated, which substantiallypromoted the consumption of HNO3, HClO4, andtheir decomposition products in kinetics. Additionally, the energyperformances of AP- and AN-based propellants doping with TAGN wereevaluated. It is disclosed that the introduction of TAGN would notresult in improvement in the energy performance of propellants, butdue to its energetic property and high hydrogen content, proper introductionof TAGN will not reduce the energy performance of propellants in alarge degree compared with the introduction of inert catalysts.