Investigation of the Thermal Aging Behavior of Pyrotechnic Tracer Composition by Spectroscopic Techniques Coupled with Principal Component Analysis

Abstract

AbstractThis work aims to investigate the aging behavior related to heat of a pyrotechnic tracer composition (PTC) sample composed of strontium nitrate as an oxidizer and dual‐fuel of Mg and Mg−Al alloy. Fresh and thermally aged samples were examined using nondestructive spectroscopic techniques, namely Raman spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X‐ray diffraction (XRD). The obtained results showed that aging for 20, 40, and 60 days at 65 °C does not provoke noticeable chemical or structural changes, whereas, after 60 days, the changes are visible, and become more obvious after aging for 120 days. These changes are caused by the partial decomposition of strontium nitrate and the oxidation of magnesium, which are followed by the generation of degradation products such as Sr(NO2)2, MgO, and Mg(OH)2. On the other hand, the applicability of FTIR and XRD associated with a chemometric tool, the principal component analysis, as a simple and useful technique has been also assessed to discriminate the spectra of the aged samples. It has been revealed that these combined approaches can be effectively used to recognize the main compositional and structural changes within the pyrotechnic tracer composition affected by the thermal degradation process.