The Impact of Metastable Intermolrecular Nanocomposite Particles on Kinetic Decomposition of Heterocyclic Nitramines Using Advanced Solid‐Phase Decomposition Models

Journal of Inorganic and Organometallic Polymers and Materials - Surface oxygen of oxide catalyst has low coordination number; they are negatively charged. Surface oxygen can act active site for...     

Microwave-Assisted Synthesis of the Flexible Iron-based MIL-88B Metal–Organic Framework for Advanced Energetic Systems

The 3D metal–organic framework (MOF), MIL-88B, built from the trivalent metal ions and the ditopic 1,4-Benzene dicarboxylic acid linker (H₂BDC), distinguishes itself from the other MOFs for its flexibility and high thermal stability. MIL-88B was synthesized by a rapid microwave-assisted solvothermal method at high power (850 W). The iron-based MIL-88B [Fe₃.O.Cl.(O₂C–C₆H₄–CO₂)₃] exposed oxygen and iron content of 29% and 24%, respectively, which offers unique properties as an oxygen-rich catalyst for energetic systems. Upon dispersion in an organic solvent and integration into ammonium perchlorate (AP) (the universal oxidizer for energetic systems), the dispersion of the MOF particles into the AP energetic matrix was uniform (investigated via elemental mapping using an EDX detector). Therefore, MIL-88B(Fe) could probe AP decomposition with the exclusive formation of mono-dispersed Fe₂O₃ nanocatalyst during the AP decomposition. The evolved nanocatalyst can offer superior combustion characteristics. XRD pattern for the MIL-88B(Fe) framework TGA residuals confirmed the formation of α-Fe₂O₃ nanocatalyst as a final product. The catalytic efficiency of MIL-88B(Fe) on AP thermal behavior was assessed via DSC and TGA. AP solely demonstrated a decomposition enthalpy of 733 J g^?1, while AP/MIL-88B(Fe) showed a 66% higher decomposition enthalpy of 1218 J g^?1; the main exothermic decomposition temperature was decreased by 71 °C. Besides, MIL-88B(Fe) resulted in a decrease in AP decomposition activation energy by 23% and 25% using Kissinger and Kissinger–Akahira–Sunose (KAS) models, respectively.

     

Infrared Signature of Novel Super-Thermite (Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/Mg) Fluorocarbon Nanocomposite for Effective Countermeasures of Infrared Seekers

Infrared (IR) guided missiles are real threat; they caused 90% of aircraft damage. Fluorocarbon polymer nanocomposite based on super-thermites can offer superior thermal signature to countermeasure IR guided missile seekers. This study reports on the sustainable fabrication of mono-dispersed colloidal Fe₂O₃ nanoparticles with 3 nm average particle size. Fe₂O₃ nanoparticles were dispersed in acetone for subsequent integration in fluorocarbon polymer. The impact of Fe₂O₃ content on thermal signature was evaluated using (FT-MIR 2–6 μm) spectrophotometer. Nanocomposite polymer with 8 wt% Fe₂O₃ offered an increase in the average intensity of α (2–3 μm) and β (4–5 μm) bands by 50 and 85% respectively to that of reference formulation. Quantification of stimulated emitting species in the combustion flame was conducted using ICT thermodynamic code. The developed nanothermite particles extended the primary reaction zone by 183%. Full discussions about combustion zones with associated exothermic chemical reactions have been represented.     

Super-Thermite (Al/Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>) Fluorocarbon Nanocomposite with Stimulated Infrared Thermal Signature via Extended Primary Combustion Zones for Effective Countermeasures of Infrared Seekers

Super-thermites can offer large amount of energy up to 16736 J/g. Flares based on super-thermites can offer superior thermal signature to countermeasure infrared (IR) guided missile seekers. This study reports on the sustainable fabrication of mono-dispersed Fe₂O₃ nanoparticles of 3 nm average particle size. Colloidal Fe₂O₃ nanoparticles were harvested from their synthesis medium and re-dispersed in acetone. Fluorocarbon polymers (teflon and viton) as well as aluminum metal fuel were integrated into Fe₂O₃/acetone colloid. The colloid mixture was granulated and mold pressed to develop the desired grain. The impact of Fe₂O₃ nanoparticles on thermal signature was assessed using (FT-MIR 1–6 µm) spectrometer. Flame propagation was investigated by video imaging of combustion wave. Combustion zones were quantified using image analysis. Quantification of flame temperature and main IR emitting species was performed using ICT thermodynamic code (virgin 2008). Nanocomposite flare with 12 wt% Fe₂O₃ offered an increase in the intensity of β band by 230% to that of reference formulation. The primary reaction zone was extended by 164%. Super-thermite particles not only offered superior spectral performance but also altered the combustion mechanism.     

Novel Colloidal Nanothermite Particles (MnO<Subscript>2</Subscript>/Al) for Advanced Highly Energetic Systems

Nanothermites (metal oxide/metal) are tremendously exothermic and run with self sustaining oxygen content. Manganese oxide is one of the most effective oxidizers for nanothermite applications. This paper reports on the sustainable fabrication of different nanoscopic forms of colloidal manganese oxides including: MnO₂ nanoparticles of 20 nm average particle size and Mn₂O₃ nanorods of 50 nm diameter and 1 µm length. TEM micrographs demonstrated mono-dispersed particles and rods. XRD diffractograms revealed highly crystalline materials. MnO₂ nanoparticles (oxygen content 37 wt%) can offer high oxidizing ability compared with Mn₂O₃ nanorods (oxygen content 30 wt%). The integration of colloidal particles into energetic matrix can offer enhanced dispersion characteristics; consequently stoichiometric binary mixture of MnO₂ and Al nanoparticles were re-dispersed in organic solvent. The integration of developed colloidal nanothermite particles into tri-nitro toluene offered enhanced shock wave strength by 35% using ballistic mortar test. Thanks to nanotechnology which offered sustainable manufacture and subsequent integration of one of the most effective nanothermite particles into highly energetic system.     

Reduced graphene oxide: a novel black body emitter for advanced infrared decoy flares

ABSTRACT

Reduced graphene oxide (RGO) possesses unique thermal and optical properties. It could act as black body emitter with high-infrared emissivity. RGO could meet wide applications in advanced infrared decoy flares. In this study, RGO nano-sheets were synthesized through the reduction of GO after applying Hummers’ method using graphite powder as a precursor. The synthesized RGO owns 10 µm dimensions and 10 nm thicknesses. TEM analysis revealed the amorphous structure of the prepared nano-sheets. XRD diffractogram demonstrated the amorphous RGO structure. Moreover, Raman spectroscopy confirmed the complete reduction of GO into RGO. In addition, decoy flare formulations based on RGO, reactive metal fuels, and fluorocarbon polymer were developed. Additionally, thermal signature was evaluated using Arc-Optics IR spectrometer (1–6 µm) to reference formulation. Our results revealed that nanocomposite flare based on 6 wt % RGO demonstrated superior spectral intensity with an increase in average intensity by 147%. Moreover, advanced radiometric performance with superior relative intensity value (?) of 0.7 was recorded. To sum up, RGO can act as an excellent source of carbonaceous materials that can strengthen incandescence emission. Surplus magnesium could vaporize and combust with substantial heat output that could promote black body emission.