KEYWORDS Additives, Ammonium perchlorate, Catalyst, High energetic material, Thermal analysis
INTRODUCTION
Materials such as ammonium perchlorate (AP), ammonium nitrate (AN), 3-nitro-3H-1,2,4-triazol-5-one (NTO), etc release a large amount of heat and gases during their decomposition. These large gases and heat released during the components’ decomposition are utilized for various applications such as destroying a target, propelling objects, etc.1–3 Changing the combustion or decomposition behavior of these materials influences the performance of explosive formulations or solid rockets propellants. Significant research has been conducted to identify alternative methodologies that focus on finding a synergistic impact between better stability and improved combustion and decomposition performance of high energetic materials.3 Various catalysts were utilized in the past for changing the thermal decomposition behaviors of high energetic materials, among which nanosize materials possess a slightly better catalytic effect for decreasing both thermal decomposition energy and decomposition of these materials.3–5 Nanosize materials have a size ranging below 100 nm and differ in properties compared to their bulk size material because of increased surface area and quantum confinement effects.6,7 e.g., a Study of Padwal and Varma8 show that the Fe2O3 nanoparticles exhibit a better effect for increasing the burning performance of solid propellants than micron size Fe2O3. The use of metal oxides, specifically 3d transition metal oxides were well studied for improving the thermal decomposition of high energetic materials.9,10 Recently, Perovskite type oxides (PTOs) have gained attention for improving the thermal performance of high energetic materials.11 PTOs have a general formula ABO3 Where A site is occupied by a larger cation such as alkaline earth metals and B site is occupied by smaller cations such as transition metal cations. PTOs can catalyze reactions such as oxidation of CO, NOX , and reduction of CO2, N2, O2, etc,12 which can potentially be produced during high energetic materials’ decomposition process and therefore, can potentially catalyze the decomposition of these materials.13–16 Use of metal oxides-reduced graphene oxide (r GO) or other carbon-based materials were known to improve the heat released during the decomposition of these high energetic materials as well as further reducing the decomposition temperature.17,18 This additional feature of metal oxides containing r GO could be assigned to r GO’s large surface support for various redox processes occurring during the decomposition.
In the present work, the catalytic effect of BaZnCuO3(BZC) on the thermal decomposition of inorganic material AP and one heterocyclic energetic material NTO was investigated. Comparative studies of the catalytic effect of pure BZC and BZC/rGO composite are also presented. BZC was synthesized using the sol-gel method and characterized using powder X-ray diffraction (XRD), Raman, and UV analysis.
EXPERIMENTAL PROCEDURES
2.1 MaterialsMetal nitrate salts (Ba2+, Zn2+, and Cu2+) were acquired from SRL Pvt. Ltd., India. GO was purchased from Merck, India. Go was thermally reduced at 350oC to rGO.19 NTO was synthesized using previously reported literature20, AP was acquired from national chemicals.2.2 Synthesis of BZC and BZC/rGOBZC was synthesized using the previously reported sol-gel citrate-disodium ethylenediaminetetraacetate (EDTA) method.21 Nitrate salts of metals Ba2+, Cu2+, and Zn2+ were mixed in the 2:1:1 ratio followed by the addition of citric acid and EDTA in 2:1 mole ratio than of total metal content. The mixture was heated between 90-100 oC to form a gel. After the combustion of gel in the open air, the obtained residue was calcined at 700 oC for 4 hours to yield BZC. BZC was mixed with rGO in a 2:1 ratio in acetone followed by ultrasound irradiation for 40 minutes and drying in an oven to yield BZC/rGO composite.2.3 Preparation of energetic material sample containing catalystThe obtained BZC and BZC/rGO were mixed with NTO and AP to study their catalytic influence on the decomposition of AP and NTO. The composition of the samples and their labeling is depicted in Table 1.
Table 1. Samples for NTO and AP in the presence of different additives for thermal decomposition studies