Comparative study on aluminum agglomeration characteristics in HTPB and NEPE propellants: The critical effect of accumulation

Li, Shipo; Xiang, Lin; Liu, Lu; Yue, Songchen; Liu, Peijin; Ao, Wen

doi:10.1016/j.combustflame.2022.112607

Cited by 18 publications

(10 citation statements)

References 30 publications

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“…Figure 12 illustrates the mechanism by which AlH 3 inhibits agglomeration. Particles leave the burning surface when the aerodynamic force acting on the particles exceeds the adhesion force [40]. Increasing the burning rate of the propellant can create a high gas flow velocity, thereby increasing the aerodynamic force.…”

Section: Resultsmentioning

confidence: 99%

Reduction of agglomeration effect by aluminum trihydride in solid propellant combustion

Gou,

Hu,

et al. 2023

Propellants Explo Pyrotec

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Aluminum trihydride (AlH3) has gained considerable attention as a substitute fuel for aluminum in solid propellants. In this study, we conducted a systematic investigation to evaluate the effects of AlH3 content, ranging from 0 % to 18 %, on propellant ignition, combustion, and agglomeration. Experimental methods such as thermogravimetry−differential scanning calorimetry (TG‐DSC), laser ignition, high‐speed photography, and collecting condensed combustion products (CCPs) were employed. The results indicate that AlH3 significantly promotes the high‐temperature decomposition of ammonium perchlorate (AP). Meanwhile, the addition of cyclotetramethylene tetranitramine (HMX) in propellant does not affect the hydrogen release reaction of AlH3. As the AlH3 content increases from 0 % to 18 %, the spectral emission intensity of the propellants decreases, and the ignition delay time initially increases from 253 ms to 321 ms, and then decreases to 258 ms. Furthermore, the burning rate increases with increasing the AlH3 content, while the pressure exponent is reduced from 0.551 to 0.460. The inclusion of AlH3 in propellants significantly inhibits aluminum agglomeration near the burning surface. Additionally, as the AlH3 content increases, the mean particle size D43 of the CCPs decreases from 50.95 μm to 8.28 μm at 1 MPa. The agglomeration degree of aluminum is very weak at 7 MPa, especially when the AlH3 content exceeds 9 %. The conclusions drawn from this study can serve as valuable guidance for optimizing propellant formulations.

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Section: Resultsmentioning

confidence: 99%

Reduction of agglomeration effect by aluminum trihydride in solid propellant combustion

Gou,

Hu,

et al. 2023

Propellants Explo Pyrotec

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“…During the combustion process, particles ejected from the condensed phase to the gas phase must get enough aerodynamic force to overcome the adhesion between the particles and the binder. 33 Both RDX and AP have a decomposition temperature below 400°C, making them highly susceptible to rapid decomposition when the condensed phase is quickly heated. However, aluminum has a melting temperature above 600°C and does not decompose directly.…”

Section: Combustion Process Characterizationmentioning

confidence: 99%

“…The brightest flame region is mainly contributed by the combustion of aluminum particles, which can help to identify the agglomeration of aluminum. 33 The bright areas of HF-1 are mainly located near the combustion surface, while the combustion in the gas phase is relatively sparse. This phenomenon indicates that instead of completely detaching the burning surface, the melted aluminum particles in HF-1 formed agglomerations on the burning surface.…”

Section: Combustion Process Characterizationmentioning

confidence: 99%

“…The surface of the coarse spheres in the combustion residue of sample HF-1 shows cracks and "cap-shaped" oxides, which is related to the stress that the propellant undergoes during combustion. 33,41 With the increase of PFD content in the sample, the proportion of nanoscale particles increases sharply, while the proportion of micrometer-sized coarse spheres decreases correspondingly. According to Babuk et al, 42 the regular spherical particles observed in the CCPs are primarily composed of Al 2 O 3 .…”

Section: Combustion Heat and Residue Characterizationmentioning

confidence: 99%

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A new fluorocarbon adhesive: Inhibiting agglomeration during combustion of propellant via efficient F–Al₂O₃ preignition reaction

Yao,

Xia,

Wang

et al. 2024

Carbon Energy

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Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants. In this investigation, the hydroxyl‐terminated structured fluorinated alcohol compound (PFD) was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization (HTPE) binder; that is, a unique fluorinated polyether (FTPE) binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing. The FTPE was applied in aluminum‐based propellants for the first time. Due to the complete release of fluorinated organic active segments in the range of 300°C to 400°C, the burning rate of FTPE‐based propellant increased from 4.07 (0% PFD) to 6.36 mm/s (5% PFD), increased by 56.27% under 1 MPa. The reaction heat of FTPE propellants increased from 5.95 (0% PFD) to 7.18 MJ/kg (5% PFD) under 3.0 MPa, indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products (CCPs) dropped by 81.84% from 75.46 (0% PFD) to 13.71 μm (5% PFD) under 3.0 MPa, in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants. Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments, which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion, and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.

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“…However, traditional Al powders, particularly those with micron-sized particles, suffer from prolonged ignition delay owing to the presence of an Al oxide layer on their surface. This issue leads to the formation of sizable Al droplets during propellant combustion, resulting in a lower combustion efficiency and thereby restricting their application in propellants [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Enhancing RDX Thermal Decomposition in Al@RDX Composites with Co Transition Metal Interfacial Layer

Yang,

Xie,

Wang

et al. 2024

Aerospace

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In this study, an Al/Co@RDX composite was meticulously prepared through a combination of planetary high-energy ball-milling and a spray-drying technique. The thermal reactivity of these Al/Co@RDX composites was comprehensively investigated and compared using the TG/DSC technique. It is shown that the initial decomposition temperature of RDX in the DSC curve was decreased by 26.3 °C in the presence of Al/Co, which could be attributed to the nano-sized Co transition metal catalyzing the decomposition reaction of nitrogen oxides in RDX decomposition products. The decomposition peak temperature of RDX and the heat released by the thermal decomposition of RDX in the Al/Co@RDX composite were decreased by 26.3 °C and increased by 74.5 J·g−1, respectively, in comparison with those of pure RDX. The types of major gaseous products released from Al/Co@RDX were found to be identical to those of pure RDX, encompassing N2O, CH2O, CO2 and HCN. However, the concentrations of those gaseous products for Al/Co@RDX were higher than those observed for pure RDX, which may owe to the fact that the Al/Co composite can interact with the –CH2 and –NO2 within RDX molecules, which leads to the weakening of the C-N and N-N bonds. In addition, the decomposition of RDX in the Al/Co@RDX composite was observed as a one-step process with an apparent activation energy (Ea) of 115.6 kJ·cm−3. The decomposition mechanism of the RDX in the Al/Co@RDX composite was identified to follow the chain scission model (L2), whereas the two-step decomposition physical models observed for pure RDX were found to closely resemble the L2 and autocatalytic models.

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Comparative study on aluminum agglomeration characteristics in HTPB and NEPE propellants: The critical effect of accumulation

Cited by 18 publications

References 30 publications

Reduction of agglomeration effect by aluminum trihydride in solid propellant combustion

Reduction of agglomeration effect by aluminum trihydride in solid propellant combustion

A new fluorocarbon adhesive: Inhibiting agglomeration during combustion of propellant via efficient F–Al₂O₃ preignition reaction

Enhancing RDX Thermal Decomposition in Al@RDX Composites with Co Transition Metal Interfacial Layer

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Comparative study on aluminum agglomeration characteristics in HTPB and NEPE propellants: The critical effect of accumulation

Cited by 18 publications

References 30 publications

Reduction of agglomeration effect by aluminum trihydride in solid propellant combustion

Reduction of agglomeration effect by aluminum trihydride in solid propellant combustion

A new fluorocarbon adhesive: Inhibiting agglomeration during combustion of propellant via efficient F–Al2O3 preignition reaction

Enhancing RDX Thermal Decomposition in Al@RDX Composites with Co Transition Metal Interfacial Layer

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Product

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A new fluorocarbon adhesive: Inhibiting agglomeration during combustion of propellant via efficient F–Al₂O₃ preignition reaction