A new nitride sprayed aluminum/copper ferrite (Al/CuFe2O4@NC) high explosive composite with intermediate energy release was developed through electrodeposition in a study published in the journal Fuel.
Study: Effects of oxidizer and architecture on the thermochemical reactivity, laser ignition and combustion properties of nanothermite. Image Credit: agsandrew/Shutterstock.com
In Al/CuFe2O4@NC microparticles, intimate interaction and homogeneous distribution of the fuel (Al) and oxidizer (CuFe2O4) were obtained.
An Introduction to Nanothermite
Nanothermite, a subgroup of metastable intermixed composites (MICs), is a composite made up of a fuel (such as Al, Mg, or B) and an oxidizer (such as polymer materials and metal oxides) that has high power density and improved initiation and burning performance than standard CHNO systems. Furthermore, its qualities may be modified by altering the oxidant, choosing suitable compounds, and improving interfacial contact among constituents, which has attracted the interest of researchers all around the world.
Nanothermite ignition is a complicated multistage mechanism that includes a thermal conductivity process, induction, feedback, and emission. Because of the phase transition of the fuel and oxidizer in the nanocomposite, energy transfer and thermal dispersion govern the reaction rates.
In terms of composite structures, homogenous dispersion and intimacy indicate a close interfacial connection between constituents and small distances of mass transport and thermal propagation, which is significantly favorable for increasing reaction rate and enhancing high explosive composite burning qualities.
Why Electrospray is the Preferred Method of Assembling Nanothermite
In recent decades, significant efforts have been made to investigate nanomaterials with superior energy density and outstanding ignition characteristics.
The preparation of thoroughly blended composite materials for enhancing the contact area and improving heat release and burning effectiveness of nanothermite, numerous integrated innovations such as thermonuclear deposition technique, self-assembly, sol–gel synthesizing, electrochemical methods, on-site growth, and arrested reactive milling (ARM) have been used.
However, the resultant composite is disorganized in some situations, leading to volatile and unrepeatable combustion characteristics. Furthermore, unfavorable conditions such as extreme heat and powerful abrasive environments are necessary for some manufacturing methods, resulting in a drop in active aluminum concentration and a spike in safety threats.
Electrospray, on the other hand, is a simple way of building homogeneous microparticles with various potential benefits in the control and management of nanoparticle constituents, size distribution, and design. The electrospray assembly technique may also effectively stop further oxidation of the aluminum while also improving interfacial contact between elements.
Significance of Oxidizer Type
Another important aspect in temperature increase, combustion, and ignition efficiency of nanocomposite is the oxidant kind in thermite.
Many recent studies on thermite have focused on the fabrication and performance enhancement of Al/CuO, Al/Fe2O3, Al/Bi2O3, Al/NiO, and Al/WO3 MICs in which the oxidizer is primarily focused on metal oxides using different complex assembly processes. Despite substantial development, thermite composites' customizable sensitivity still confronts certain obstacles because the composition of the oxidizer has a major impact on the kinetic parameters and redox potential of the thermite composites.
Composite metal oxides integrate the qualities of two types of individual metal oxides to provide unique traits such as electrical properties, good catalytic efficiency, and synergistic influences. Because it has higher catalytic characteristics than individual metal oxides, it has been widely employed in treating functional materials. There have also been a few reports of synthetic metal oxides being utilized as an oxidizer in thermite composites.
Findings of the Research
An electrospray technique was used to create thermite composites with various oxidizers (CuO, Fe2O3, and CuFe2O4), and the homogenous dispersion and close interface interaction between the fuel and oxidizer were well developed.
The composites' reaction characteristics were tested, and the Al/CuFe2O4@NC composite was found to exhibit a fairly comprehensive reaction and a substantial heat flux in the solid-solid response.
When compared to Al/[email protected], Al/Fe2O3@NC, and a physical mixing of Al and CuFe2O4, the Al/CuFe2O4[email protected] composite had a reduced combustion delay period and a milder flame propagation. By altering the NC concentration, the ignition efficiency of the Al/CuFe2O4@NC composite may be adjusted.
Al/CuFe2O4@NC has a slower combustion efficiency than Al/[email protected] and Al/Fe2O3@NC. When compared to Al/[email protected] and Al/Fe2O3@NC composites, Al/CuFe2O4@NC composites exhibit a low pressurization rate and a long duration, signifying moderate combustion.
To summarize, the oxidizer in thermite compounds has a substantial impact on the power transfer, combustion latency, and burning parameters.
The homogeneous distribution and intimate interfacial interaction between the fuel and oxidizer are advantageous in reducing mass transport and heat dispersion ranges, resulting in improved performance. This research offers an approach for developing and enhancing innovative conductive polymers.
Continue reading: Breakthrough for Atomic Arrangement of Amorphous Materials.
Wang, W., Li, H., et al. (2022). Effects of oxidizer and architecture on the thermochemical reactivity, laser ignition and combustion properties of nanothermite. Fuel, 314. Available at: https://www.sciencedirect.com/science/article/pii/S0016236122000138?via%3Dihub