Changes in the state of matter of KCIO 4 to improve thermal and combustion properties of Al/MoO 3 nanothermite.

To improve the thermal and combustion properties of nanothermites, a design theory of changing the state of matter and structural state of the reactants during reaction was proposed. The Al/MoO ₃ /KClO ₄ (Kp) nanothermite was prepared and the Al/MoO ₃ nanothermite was used as a control. SEM and XRD were used to characterize the nanothermites; DSC was used to test thermal properties; and constant volume and open combustion tests were performed to examine their combustion performance. Phase and morphology characterization of the combustion products were performed to reveal the mechanism of the aluminothermic reaction. The results show that the Al/MoO ₃ /Kp nanothermite exhibited excellent thermal properties, with a total heat release of 1976 J·g ^- 1 , increasing by approximately 33% of 1486 J·g ^- 1 of the Al/MoO ₃ nanothermite, and activation energy of 269.66 kJ·mol ^- 1 , which demonstrated higher stability than the Al/MoO ₃ nanothermite (205.64 kJ·mol ^- 1 ). During the combustion test, the peak pressure of the Al/MoO ₃ /Kp nanothermite was 0.751 MPa, and the average pressure rise rate was 25.03 MPa·s ^- 1 , much higher than 0.188 MPa and 6.27 MPa·s ^- 1 of the Al/MoO ₃ nanothermite. The combustion products of Al/MoO ₃ nanothermite were Al ₂ O ₃ , MoO, and Mo, indicating insufficient combustion and incomplete reaction, whereas, the combustion products of Al/MoO ₃ /Kp nanothermite were Al ₂ O ₃ , MoO, and KCl, indicating complete reaction. Their "coral-like" morphology was the effect of reactants solidifying after melting during the combustion process. The characterization of reactants and pressure test during combustion reveals the three stages of aluminothermic reaction in thermites. The excellent thermal and combustion performance of Al/MoO ₃ /Kp nanothermite is attributed to the melt and decomposition of Kp into O ₂ in the third stage. This study provides new ideas and guidance for the design of high-performance nanothermites.
(© 2024. The Author(s).)