The aging of pyrotechnics is heavily influenced by temperature and humidity during their long-term storage. The investigation of the aging mechanisms of such composites is of great interest for their safe storage and use in weapon systems, hence avoiding any unexpected phenomenon or decrease in performance. This study is aimed at understanding the aging effects related to temperature and moisture on pyrotechnic delays composed of silicon as fuel and lead oxide (Pb₃O₄) and barium chromate (BaCrO₄) as oxidizers. The aged samples were considered for spectroscopic analysis using Fourier transformed infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction spectroscopy (XRD), and surface morphology analysis using scanning electron microscopy (SEM). The results obtained showed that temperature and moisture induce distinct structural and morphological modifications on the composition. The thermal aging causes thermal decomposition of the lead oxide, followed by the oxidation of the fuel particles to form silicon dioxide (SiO₂). On the other hand, under moisture, the lead oxide is stable and does not participate in the aging process and the barium chromate is converted to chromium oxide molecules Cr₂O₃. At the same time, Si is oxidized to SiO₂ and orthosilicic acid Si(OH)₄ in the presence of humidity. The SEM images revealed that the surface of the aged samples tended to be rough in addition to the formation of surface cracks. At low aging periods of 20, 40, and 60 days, no chemical alterations have been noticed, whereas, beyond 80 days, the changes become more apparent. By coupling the above analytical techniques with principal component analysis (PCA), it was possible to accurately differentiate the aged samples according to their aging time and to detect any compositional change within the powder even at low aging periods.

中文翻译：

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通过结合光谱技术深入了解硅基烟火延迟组合物的热老化和湿老化 - 主成分分析方法

烟火的老化在长期储存过程中受温度和湿度的影响很大。研究此类复合材料的老化机制对于它们在武器系统中的安全储存和使用具有重要意义，从而避免任何意外现象或性能下降。本研究旨在了解与温度和湿度相关的老化对由硅作为燃料和氧化铅 (Pb ₃ O ₄ ) 和铬酸钡 (BaCrO _{4 ) 组成的烟火延迟的影响。}) 作为氧化剂。使用傅里叶变换红外光谱 (FTIR)、拉曼光谱、X 射线衍射光谱 (XRD) 和使用扫描电子显微镜 (SEM) 的表面形态分析对老化样品进行光谱分析。获得的结果表明，温度和湿度会导致组合物发生明显的结构和形态变化。热老化导致氧化铅热分解，随后燃料颗粒氧化形成二氧化硅(SiO ₂ )。另一方面，在湿气下，氧化铅稳定，不参与老化过程，铬酸钡转化为氧化铬分子Cr ₂ O ₃。同时，Si被氧化成SiO₂和原硅酸 Si(OH) ₄在湿气存在下。SEM图像显示，老化样品的表面除了形成表面裂纹外，还趋于粗糙。在 20、40 和 60 天的低老化期，没有发现化学变化，而超过 80 天，变化变得更加明显。通过将上述分析技术与主成分分析 (PCA) 相结合，可以根据老化时间准确区分老化样品，并检测粉末内的任何成分变化，即使在低老化期也是如此。