Journal
CERAMICS INTERNATIONAL
Volume 47, Issue 12, Pages 16500-16510Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2021.02.218
Keywords
Al/MoO3 thermite; Ball milling; Thermal kinetics; Reaction mechanism
Categories
Funding
- National Natural Science Foundation [51704302]
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The addition of CuO significantly increases the heat release and decreases the exothermic peak temperature of Al/MoO3 thermite, but when the mass fraction of CuO reaches a certain level, violent explosion reactions occur.
To explore the influence of CuO additive on the thermal kinetics and combustion performance of thermite, Al/MoO3 thermite composites with different mass fractions of CuO were prepared by ball milling. Field emission scanning electron microscope (FE-SEM), X-ray diffractometer (XRD), and differential scanning calorimeter (DSC) were used to test the samples. From the DSC results, Al/MoO3 thermite and Al/CuO thermite released 1066 J/g and 849 J/g heat, respectively. The peak temperature of the exothermic reaction was 560.22 degrees C and 609.43 degrees C. Interestingly, the Al/MoO3 thermite with 5% CuO released higher heat, about 1747 J/g. The temperature of the exothermic peak was also greatly advanced to 526 degrees C. Thermodynamic analysis results showed that the activation energy (Ea) of Al/MoO3/5% CuO thermite was merely 184.75 kJ mol(-1), which was a decrease of 18.3% and 20.8% of the Al/MoO3 and Al/CuO thermite. The reaction mechanism function of Al/MoO3 thermite, Al/MoO3/5% CuO and Al/CuO thermite can be set as f(alpha) = 1 - alpha. The fast electric heating wire ignition experiment showed that the flame brightness of the Al/MoO3/5% CuO thermite was the brightest and the burning time was the longest. Surprisingly, when the mass fraction of CuO additives in Al/MoO3 thermite reached 10% and 20%, the thermal kinetics and combustion performance of the thermite were completely changed. There was a violent and sharp exothermic peak accompanied by a large amount of heat release of 2042 J/g and 2252 J/g, respectively. The reaction mechanism of Al/MoO3 thermite with 10% and 20% CuO addition can be set as f(alpha) = 3/2*(1 - alpha)[-ln(1 - alpha)](1/3). The burning speed became faster and the flame was bright with sparks. This work lays the foundation for the further study of the thermite mechanism.
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