Thermochemical characterization of Zr/Fe2O3 pyrotechnic mixture under natural aging conditions

Abstract

This study investigated the aging characteristics of naturally aged primer that uses zirconium (Zr) as a metallic fuel and iron oxide (Fe2O3) as an oxidizer. Naturally aged samples showed a significant reduction in heat of reaction and an increase in activation energy compared to thermally aged samples. The aging processes of a Zr/Fe2O3 pyrotechnic mixture were proposed using X-ray photoelectron spectroscopy. X-ray powder diffraction experiments verified the proposed processes and further confirmed that natural aging promotes the formation of thermally stable monoclinic ZrO2. The oxygen diffusion depth into the Zr surface layer and ZrO2 layer thickness were measured by transmission electron microscopy–energy-dispersive X-ray spectroscopy and fast Fourier transform. The exposure to seasonal humidity during natural aging affected both Zr and Fe2O3 and, in turn, made the mixture more difficult-to-ignite, resulting in the following effects: decrease in heat of reaction, formation of reaction products, and crystal structure growth in the direction of reducing reactivity.

Towards a Deep Insight Into Thermal and Moisture Aging of Silicon‐Based Pyrotechnic Delay Composition Through a Combination of Spectroscopic Techniques – Principal Component Analysis Approaches

“…Therefore, scientists employed accelerated aging techniques [13][14][15][16][17], which enable us to observe the effect of an experimental (non-natural) stress over a short time frame with which one can estimate the lifetime of the aged samples [18][19][20][21]. Several works published so far aimed at understanding the aging of pyrotechnic compositions [8,17,[22][23][24] under various aging conditions, i. e., temperature and humidity. Despite that, only a few of them have studied the aging of pyrotechnic delay compositions [8,10,16,25,26].…”

“…The mechanisms taking place during the aging of pyrotechnic compositions have been investigated mainly from the aspect of thermochemical characterization in order to determine the thermodynamic and kinetic parameters of these materials [16,24,34]. However, several studies followed quite interesting approaches consisting of the use of non-calorimetric methods or spectroscopic techniques such as XRD, Raman, photoelectron spectroscopy, etc.…”