Effect of CuO on the thermal kinetics and combustion properties of Al/MoO3 thermite prepared by ball milling

Abstract

Abstract 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\xa0J/g and 849\xa0J/g heat, respectively. The peak temperature of the exothermic reaction was 560.22\xa0°C and 609.43\xa0°C. Interestingly, the Al/MoO3 thermite with 5% CuO released higher heat, about 1747\xa0J/g. The temperature of the exothermic peak was also greatly advanced to 526\xa0°C. Thermodynamic analysis results showed that the activation energy (Ea) of Al/MoO3/5% CuO thermite was merely 184.75\xa0kJ\xa0mol−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 ( α ) = 1 − α . 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\xa0J/g, respectively. The reaction mechanism of Al/MoO3 thermite with 10% and 20% CuO addition can be set as f ( α ) = 3 / 2 ∗ ( 1 − α ) [ − ln ( 1 − α ) ] 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.