Reactivity adjustment from the contact extent between CuO and Al phases in nanothermites

Abstract

The development of nanothermites with adjustable reactivity has always been the research hotspot in the field of energetic materials, and its key issue is to control the interfacial contact extent and diffusion length between fuel and oxidizer. Here, the 3DOM CuO/Al, 3DOM CuO/Al-NPs and CuO-NPs/Al-NPs nanothermites, which show a gradual decrease in contact extents between reactants, were firstly prepared simultaneously using magnetron sputtering, P4VP self-assembly and ultrasonic mixing, respectively. The DSC thermograms show that the heat release of the 3DOM CuO/Al (sputtering 200 nm Al) can reach 2541.4 J/g, much larger than either value of the prepared 3DOM CuO/Al-NPs and CuO-NPs/Al-NPs. The activation energies of these CuO/Al systems also exhibit the similar results as the heat releases. However, the 3DOM CuO/Al-NPs can lead to the highest combustion pressure (24.6 MPa), the shortest pressure rise time (0.067 ms), and the fastest pressurization rate (647.98 GPa/s), followed orderly in corresponding values by the CuO-NPs/Al-NPs and 3DOM CuO/Al. All data indicate that the contact extent between CuO and Al plays a great effect on the overall reactivity, and their differences in structure and volume are responsible for the diverse combustion pressure performance. Furthermore, the presence of reaction voids between components can promote the O diffusion to enhance the continuous mass and heat transfer for an efficacious reaction. Hence, it is believed that similar methods can be used to improve the contact extent and diffusion length between fuels and oxidants so as to achieve an adjustment in reactivity for various nanothermites.