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ABSTRACT
In this work, the energetic Al/CuO nano-thermite is chosen as a promising additive to improve the reaction characteristic of μAl powder in heated steam at 600–900°C. The ignition temperature, ignition delay time, and combustion efficiency were experimentally measured. After all the reaction products were collected, the surface morphologies and phase compositions were analyzed using a scanning electron microscopy and an X-ray diffraction. Results show that the addition of Al/CuO nano-thermite to μAl powder, the corresponding ignition temperature, and ignition delay time drop considerably. Meanwhile, they also emerge a significant decreasing trend as the furnace temperature increases. At 900°C, the μAl-12 wt%Al/CuO sample exhibits the lowest ignition temperature of approximately 100°C and the shortest delay time of 9.4 s. In addition, the combustion efficiencies of μAl powder without addition of Al/CuO are quite low at 700°C and 800°C, less than 10%, while adding various contents of Al/CuO nano-thermite significantly increase its efficiency. However, at 900°C, the combustion efficiency of μAl-Al/CuO sample is lower than that of μAl powder without the addition of Al/CuO. Combustion product analysis suggests that the formation of CuAl2 layer on the μAl particle surface blocks the interaction of the fresh Al and surrounding water molecules. The relationship between the above parameters associated with reaction characteristics and the product characterization was discussed to reveal the complicated combustion mechanism of μAl-Al/CuO powder in steam.