Comparative investigations of ternary thermite Al/Fe2O3/CuO and Al/Fe2O3/Bi2O3 from pyrolytic, kinetics and combustion behaviors

Abstract

To develop new energy enhancement energetic materials with great combustion performance and thermal stability, two kinds of ternary thermite, Al/Fe2O3/CuO and Al/Fe2O3/Bi2O3, were prepared and analyzed via mechanical ball milling. The samples were characterized by SEM, XRD, TG-DSC, constant volume and constant pressure combustion experiments. The first exothermic peaks of Al/Fe2O3/CuO and Al/Fe2O3/Bi2O3 appear at 579 °C and 564.5 °C, respectively. The corresponding activation energies are similar. The corresponding mechanism functions are set as G(α)=[−ln(1−α)]3/4 and G(α)=[−ln(1−α)]2/3, respectively, which belong to the Avrami-Erofeev equation. Al/Fe2O3/CuO has better thermal safety. For small dose samples, its critical temperature of thermal explosion is 121.05 °C higher than that of Al/Fe2O3/Bi2O3. During combustion, the flame of Al/Fe2O3/CuO is spherical, and the main products are FeAl2O4 and Cu. The flame of Al/Fe2O3/Bi2O3 is jet-like, and the main products are Al2O3, Bi and Fe. Al/Fe2O3/Bi2O3 has better ignition and gas production performance. Its average ignition energy is 4.2 J lower than that of Al/Fe2O3/CuO. Its average step-up rate is 28.29 MPa/s, which is much higher than 6.84 MPa/s of Al/Fe2O3/CuO. This paper provides a reference for studying the thermal safety and combustion performance of ternary thermite.

Keywords

• Ternary thermite
• Thermal kinetics
• Reaction mechanism
• Combustion