Influencing factors of high-pressure discharge nanothermite composites based on $\mathrm{Al}/\mathrm{Bi}_2\mathrm{O}_3$

To optimize the reactant synthesis and improve the pressure property of $\mathrm{Al}/\mathrm{Bi}_2\mathrm{O}_3$, the influencing factors in the dynamic pressure discharge of nanothermite reactions are investigated, including the oxide type, $\mathrm{Bi}_2\mathrm{O}_3$ particle size, and fuel-to-oxidant mole ratio. All samples are prepared by the ultrasonic mixing method. The synthesized $\mathrm{Al}/\mathrm{Bi}_2\mathrm{O}_3$ composites are characterized by X-ray diffraction analysis and scanning electron microscopy. By using a closed bomb, the pressure discharge characteristics, including the peak pressure, ignition delay time, and pressurization rate, are obtained. Among the as-prepared nanothermites $\mathrm{Al}/\mathrm{CuO}$, $\mathrm{Al}/\mathrm{Fe}_2\mathrm{O}_3$, and $\mathrm{Al}/\mathrm{Bi}_2\mathrm{O}_3$, the latter shows the best pressure discharge performance. For the $\mathrm{Al}$($100$ nm)/$\mathrm{Bi}_2\mathrm{O}_3$ ($47$ nm) composite with an optimal stoichiometric ratio, the maximum peak pressure, the pressurization rate, and the shortest ignition delay time are $4559$ kPa, $11.398$ GPa/s, and $27.20$ ms respectively. The results indicate that the nano-$\mathrm{Bi}_2\mathrm{O}_3$ particle size also produces a significant effect on the pressure output.