Understanding the effects of hygrothermal aging on thermo-chemical behaviour of Zr-Ni based pyrotechnic delay composition

Abstract

This study is aimed at understanding the aging effects related to heat and moisture on the pyrotechnic delay samples composed of zirconium-nickel (Zr-Ni) alloy as fuel and oxidants such as potassium perchlorate (KClO4) and barium chromate (BaCrO4). Naturally aged samples, thermally aged samples, and hygrothermally aged samples were considered in the thermal analysis using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), chemical analysis using x-ray photoelectron spectroscopy (XPS), and surface analysis using scanning electron microscope (SEM). High-speed photography was used to determine the ignition delay time and to observe the combustion behaviour of these samples. The numerical modelling on the reaction progress was performed, and the result indicated that heat accelerated the decomposition of KClO4 only, thereby promoting fast degradation of the performance of Zr component. Moisture, on the other hand, affected the decomposition of all KClOx (0 ≤ x ≤ 4) and degradation of the performance of both Zr and Ni components. Thus, moisture effect as opposed to heat was more prominent in the increased ignition delay time and subsequent ignition failure, which also induced surface cracks and overall oxidation of the metallic fuel, namely Zr-Ni alloy.