Showing papers on "Ammonium perchlorate published in 2018"

Bipyrazole bearing ten nitro groups – a novel highly dense oxidizer for forward-looking rocket propulsions

Abstract: Taking into account the manifold requirements for future rocket industry breakthroughs, the scientific community is currently focusing on the design of novel higher performance, high-tech and environmentally more acceptable materials compared with conventional propellant ingredients for liquid, solid, gelled, and hybrid propellant systems. Earlier, considerable efforts were made to find environmentally friendly chlorine free alternatives to ammonium perchlorate (AP) which is still the main oxidizer for solid propellants; however, success in this way is extremely rare. In this work, a novel oxygen-rich energetic material, 4,4′,5,5′-tetranitro-2,2′-bis(trinitromethyl)-2H,2′H-3,3′-bipyrazole (11), was obtained by N-alkylation of 4,4′,5,5′-tetranitro-2H,2′H-3,3′-bipyrazole (9) with bromoacetone and subsequent nitration. X-ray single-crystal diffraction confirmed its structure and revealed a unique high crystal density of 2.021 g cm−3 at room temperature, introducing it into the top three of the densest CHNO compounds known. This high density material has an attractive positive oxygen balance, acceptable sensitivity, and enthalpy of formation (on a unit of weight) similar to CL-20, with calculated specific and effective impulses exceeding those of AP and ADN, making it a competitive replacement for AP as a green energetic oxidizer for diverse propellants.

The high efficient catalytic properties for thermal decomposition of ammonium perchlorate using mesoporous ZnCo 2 O 4 rods synthesized by oxalate co-precipitation method

Abstract: Mesoporous ZnCo2O4 rods have been successfully prepared via oxalate co-precipitation method without any template. The nano-sized spinel crystallites connected together to form mesoporous structure by annealing homogeneous complex oxalates precursor at a low rate of heating. It is found that the low anneal rate plays an important role for the formation of mesoporous ZnCo2O4 rods. The effects of the heat temperature on the phase, morphology and catalytic properties of the products were studied. The XRD, SEM TEM, and N2 absorption/desorption have been done to obtain compositional and morphological information as well as BET surface area of the as-prepared sample. Catalytic activities of mesoporous ZnCo2O4 rods toward the thermal decomposition of ammonium perchlorate (AP) were investigated with differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques. The results show that the addition of ZnCo2O4 rods to AP dramatically reduces the decomposition temperature. The ZnCo2O4 rods annealed at 250 °C possesses much larger specific area and exhibits excellent catalytic activity (decrease the high decomposition temperature of AP by 162.2 °C). The obtained mesoporous ZnCo2O4 rods are promising as excellent catalyst for the thermal decomposition of AP.

CuO nanoparticles supported on three-dimensional nitrogen-doped graphene as a promising catalyst for thermal decomposition of ammonium perchlorate

Abstract: In the present work, CuO nanoparticles grown on three-dimensional nitrogen-doped graphene-based frameworks (CuO@3D-(N)GFs) were synthesized using a two-step method. After the synthesis of three-dimensional nitrogen-doped graphene, CuO nanoparticles were deposited on it, by adding cupric acetate followed by thermal treatment. Different analysis methods were used to characterize the products. The as-prepared nanocomposite was used as a promising catalyst for thermal decomposition of ammonium perchlorate (AP) as one of the most common oxidizer in composite propellants. Differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) techniques were used to investigate the thermal decomposition of ammonium perchlorate. According to the DSC/TGA, high temperature decomposition of AP decreased to 111 °C in the presence of 4% CuO@3D-(N)GFs and the total heat release (ΔH) from decomposition of AP increased to 1893 J g−1 which is much more than 590 J g−1 for pure AP.

Effect of rGO–Fe2O3 nanocomposites fabricated in different solvents on the thermal decomposition properties of ammonium perchlorate

Abstract: rGO–Fe2O3 composites were prepared using different solvents (distilled water, ethanol, N-methylpyrrolidone, ethyl acetate, n-butyl alcohol and N,N-dimethylformamide) via a simple solvothermal method and characterized by SEM, TEM, XRD, FT-IR, Raman and XPS techniques. Then, the catalytic action of rGO–Fe2O3 composites (prepared in different solvents), GO, rGO and pristine Fe2O3 on the thermal decomposition of ammonium perchlorate (AP) were studied using a TG-DSC instrument. DSC results showed that GO, rGO, pristine Fe2O3 and rGO–Fe2O3 composites could effectively promote the thermal decomposition of AP. Additionally, rGO–Fe2O3 fabricated in N,N-dimethylformamide (DMF) solvent possesses the best catalytic performance among the investigated materials. This result can be attributed to the better dispersibility of Fe2O3 nanoparticles on graphene oxide prepared in DMF solvent, which was confirmed by SEM and TEM imaging. The high temperature decomposition exothermic peak (HTP) and the apparent activation energy of AP are reduced by 119.6 °C and 173.3 kJ mol−1, respectively, in the presence of Fe2O3–rGO (DMF) composite.

Thermal Behavior and Thermolysis Mechanisms of Ammonium Perchlorate under the Effects of Graphene Oxide-Doped Complexes of Triaminoguanidine

Abstract: Several transition metal complexes of triaminoguanidine (TAG) nitrate, TAG-Ni, TAG-Co, graphene oxide (GO)/TAG-Ni (GT-Ni), GO/TAG-Co (GT-Co), and GO/ TAG-Cu (GT-Cu) were prepared using GO as a stabilizer. It has been shown that these complexes are promising energetic catalysts for decomposition of ammonium perchlorate (AP), which was uniformly coated with the mentioned catalysts. The decomposition kinetic parameters and mechanisms of the complexes have been studied by means of differential scanning calorimetry/thermogravimetric techniques. Results show that the presence of GO in such hybrid catalysts is able to stabilize AP before its decomposition, but the strong catalytic effects occur on HClO4 as the intermediate of the initial decomposition of AP. In the cases of TAG-Co, GT-Co, and GT-Cu, they would make the two-step decomposition of AP into a single step. The heat releases have been greatly increased as well because of a more complete decomposition. More importantly, the thermolysis mechanism of AP c...

Thermal decomposition and combustion characteristics of HTPB-coarse AP composite solid propellants catalyzed with Fe2O3

Abstract: Many factors and their mutual interactions induce complexity in the combustion of hydroxyl-terminated polybutadiene (HTPB)–ammonium perchlorate (AP)–ferric oxide (Fe2O3) composite solid propellant ...

Effect of the homo- and heterobimetallic compounds derived from s-indacene on the thermal decomposition of ammonium perchlorate

Abstract: This contribution describes an approaching about the catalytic activity of the homo- and heterobimetallic complexes derived from s-indacene on the thermal decomposition of ammonium perchlorate (abbreviate AP). The complexes, anti-[Cp*Fe-s-Ic′-FeCp*] (1), anti-[Cp*Fe-s-Ic′-CoCp*] (2), anti-[Cp*Fe-s-Ic′-NiCp*] (3) and anti-[Cp*Fe-s-Ic′-Mn(CO)3] (4) (with s-Ic′: 2,6-diethyl-4,8-dimethyl-s-indaceneiide), were compared with the catalytic activity of the catocene (cat) complex previously reported. Furthermore, in order to clarify the mechanism of the bimetallic compounds, it was tested ferrocene (Fc) compound as burning rate (BR) catalyst on the thermal decomposition of AP. These compounds shown a shift on the peak temperature to left and an increase released heats during thermal decomposition of AP. The burning rate catalytic activity of Fc, 1, 2, 3 and 4 on thermal decomposition of AP was examined by thermogravimetry and differential scanning calorimetry techniques.

Agglomerate Sizing in Aluminized Propellants Using Digital Inline Holography and Traditional Diagnostics

Abstract: Aluminized ammonium perchlorate composite propellants can form large molten agglomerated particles that may result in poor combustion performance, slag accumulation, and increased two-phase flow lo...

MnCo 2 O 4 nanoparticles with excellent catalytic activity in thermal decomposition of ammonium perchlorate

Abstract: MnCo2O4 spinel nanoparticles (NPs) have been prepared using Aloe vera gel solution. The characterization of prepared spinel was performed applying Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron spectroscope, scanning electron microscope and dynamic light scattering. The results manifested that the prepared nanoparticles were mainly spherical plus minor agglomeration with average size distribution between 35 and 60 nm. The catalytic activity of the prepared nanoparticles upon thermal degradation of ammonium perchlorate (AP) was evaluated applying differential scanning calorimetry and thermogravimetry instruments. MnCo2O4 nanoparticles increased the released heat of AP from 450 to 1480 J g−1 and decreased the decomposition temperature from 420 to 293 °C. The kinetic parameters obtained from Kissinger methods showed that the activation energy of AP thermal decomposition in the presence of MnCo2O4 NPs considerably decreased. Also, a mechanism has been proposed in the presence of catalyst for the process of thermal decomposition of AP.

Highly dispersed Ni–Mn bimetallic nanoparticles embedded in 3D nitrogen-doped graphene as an efficient catalyst for the thermal decomposition of ammonium perchlorate

Abstract: The development of efficient thermal decomposition of ammonium perchlorate (AP) to improve the combustion behavior of propellants is a vital research topic. In this work, NiMn bimetallic nanoparticles were successfully grown on three-dimensional nitrogen-doped graphene-based frameworks by the chemical co-reduction method. The as-prepared nanocomposite showed a high catalytic activity for the thermal decomposition of AP, which is probably related to the synergistic effect of Ni and Mn. The as-prepared NiMn@3D-NGF nanocomposite was characterized by spectroscopic and microscopic analyses. The catalytic activity of the as-obtained material was investigated by differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). The high-temperature decomposition of AP was decreased by 115.22 °C and the total heat release from the decomposition of AP increased from 510.40 to 1744.92 Jg−1.

Fabrication of porous MgCo2O4 with rod-like morphology and its superb catalytic activity towards ammonium perchlorate thermal decomposition

Abstract: In this paper, porous MgCo2O4 with rod-like morphology was successfully synthesized through the thermal treatment of metal oxalates precursor originated by the reaction of metal sulfates and oxalic acid, without the addition of other additives. The porous rod-like MgCo2O4, with a diameter of several hundred nanometers and a length of several micrometers, was formed through the agglomeration of numerous crystalline grains sized in 10–25 nm. Its catalytic effect on ammonium perchlorate (AP) thermal decomposition was evaluated using differential scanning calorimetry (DSC) techniques. It was found that the pyrolysis temperature of AP reduced by 129 °C and the heat release increased more than 3.19-fold with a 2 wt% addition of MgCo2O4. Meanwhile, the addition of MgCo2O4 resulted in an AP decomposition activation energy reduction from 216 kJ mol−1 to 155 kJ mol−1, calculated using the Kissinger correlation. This study provides new insights into the design and development of high performance catalysts for AP thermal decomposition.

Investigation of simultaneous formation of nano-sized CuO and ZnO on the thermal decomposition of ammonium perchlorate for composite solid propellants

Abstract: Core/shell composites of CuC2O4·2H2O@AP and ZnC2O4·2H2O@AP were prepared from metal oxalates on suspended AP particles in ethanol. CuO and ZnO nano-metal oxides as the nano-catalysts were made from CuC2O4·2H2O and ZnC2O4·2H2O simultaneously by thermal decomposition of AP. The particle size of CuO nano-particles was very finer, and the ZnO particles showed a considerable growth during formation. The kinetic triplet of activation energy, frequency factor, and model of thermal decomposition of pure AP, CuC2O4·2H2O@AP, and ZnC2O4·2H2O@AP composites were estimated by applying three model-free (FWO, KAS, and Starink) and model-fitting (Starink) methods. Based on the thermal analysis, the CuC2O4@AP composite has better catalytic performance and the thermal decomposition temperature of AP decreased to about 126.44 °C.

Synthesis of ferrocene‐modified poly(glycidyl methacrylate) and its burning rate catalytic property

Abstract: A series of ferrocene-modified poly(glycidyl methacrylate) (PGMA-Fc) compounds were synthesized and applied as burning rate catalysts in simulative solid propellant to overcome migration problems. 1H NMR and Fourier transform infrared spectroscopies and gel permeation chromatography were used to characterize the synthesized polymers. Their electrochemical behavior was evaluated using cyclic voltammetry. Their catalytic performance for the decomposition of ammonium perchlorate (AP) was investigated using thermogravimetric analysis. Anti-migration studies were conducted in migration tubes under 50°C. The results show that PGMA-Fc has a good catalytic effect on lowering the thermal decomposition temperature of AP. Anti-migration studies show that PGMA-Fc has better anti-migration performance than ferrocene and catocene.