Mitigating the negative catalytic effect of CuO by FAS-17 coated Al nanopowder: Isothermal ageing of Al/CuO nanothermite at 71 °C and 60% relative humidity

The safety and reliability of weapon systems would be significantly affected by changes in the performance of energetic materials due to ambient temperature and humidity. Nanothermites have promising applications due to their excellent reactivity. Therefore it becomes extremely important to understand their aging and failure process in the environment before using them. Here, the aging and failure process of Al/CuO in 71 °C/60% RH were investigated，and showed that CuO nanoparticles negatively catalyze Al nanopowders, resulting in rapid hydration. The anti-aging effect of FAS-17-coated Al nanopowder was also examined. The aging process of Al, Al/CuO, and Al@FAS-17/CuO in high humidity and heat environment were revealed by quasi-in situ SEM and TEM methods. Compared with the aging of pure Al, the Al nanopowder in the nanothermites strongly agglomerated with the CuO nanopowder and hydrated earlier. This may be caused by CuO catalyzed hydration of Al nanopowder.The energy release experiments showed that the performance of Al/CuO decreased rapidly and failed to ignite after 4 h of aging. In contrast, the Al@FAS-17/CuO thermite can achieve long-term stability of up to 60 h in the same environment by simple cladding of FAS-17. It is found that FAS-17 coated Al nanopowder can prevent both particle agglomeration and water erosion, which is an effective means to make nanothermites application in high humidity and heat environment.