Effect of Bismuth Oxide Particles Size on the Thermal Excitation and Combustion Properties of Thermite Systems

Graphical The particle size of Bi 2 O 3 in thermite systems has an effect on the thermal excitation threshold and combustion performance. The increase of the particle size increases the thermal excitation threshold, reduces the amount of heat release, accelerates the combustion rate, and reduces the duration of combustion. The influence of Bi 2 O 3 particles size at the sub-micron scale on the thermal excitation threshold and combustion performance of nano-thermite systems was investigated. Three formulas were designed and prepared, Al(100 nm)/Bi 2 O 3 (170 nm), Al(100 nm)/Bi 2 O 3 (370 nm) and Al(100 nm)/Bi 2 O 3 (740 nm). The samples were characterized and tested by SEM, XRD, and DSC techniques. Electrical ignition and combustion experiments were performed. The results showed that with the increase of the particle size of Bi 2 O 3 , in the case of slow linear heating, the exothermic heat decreased (1051.2 J g −1 , 527.3 J g −1 and 243.6 J g −1 ) and the thermal excitation threshold temperature increased (564.52 °C, 658.1 °C and 810.9 °C). Simultaneously, the state of the thermite reaction correspondingly changed to solid-solid, liquid-solid and liquid-liquid thermite reaction. In the case of rapid heating , the increase in particle size increased the excitation current (0.561A, 0.710A and 0.837A). During the combustion process, the thermite system with the smallest Bi 2 O 3 particle size showed the largest combustion rate, and that with the largest particle size had the longest combustion duration.