Dual-core–shell structure B@LiF@AP with multi-effect synergies to improve processibility and energy release characteristics of B

Wang, Deqi; Liu, Jie; Tan, Tianyu; Liu, Shishuo; Xu, Guozhen; Zhang, Zhimiao; Qin, Ying-zhi; Li, Fengsheng

doi:10.1039/d2ta08298e

Cited by 15 publications

(3 citation statements)

References 46 publications

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“…The high boiling point (2065 °C) makes it difficult to evaporate, resulting in longer ignition delay times and incomplete combustion. 8,14 Additionally, the presence of HOBO species has been observed in the combustion products of boron, which may indicate incomplete release of the heat of combustion of B. 15,16 To improve the ignition and combustion characteristics of boron, many groups have carried out research on the modification of boron, such as metals (Al, 17,18 Fe, 19 Ti, 15 Mg, 20 and Ni 21 ), which are more reducible and reactive compared to boron powder and can form metal borides with boron at lower ignition temperatures, thus enhancing the ignition and combustion of boron.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Both experimental and theoretical studies suggest that boron possesses an extremely high volumetric heat value (137.45 kJ/cm 3 ) and gravimetric heat value (58.74 kJ/g) among metal fuels (such as Mg, Li, Al, Zr, etc.). The volumetric heat value is 1.9 times that of Al, and the gravimetric heat value is 1.6 times that of Al. − Consequently, boron has emerged as one of the most promising metal fuel additives in propellants and explosives. − Despite this, the application of boron is not as extensive as Al. − The most important factor is the pre-existing boron oxide (B 2 O 3 ) layer with 2–5 nm thickness that forms on the surface of boron powder . This coating leads to compatibility issues with commonly used binder components in propellant formulas, specifically hydroxy-terminated polybutadiene (HTPB). , Furthermore, the low melting point (450 °C) of B 2 O 3 leads to the formation of a viscous liquid during combustion, hindering the transfer of oxygen to inner boron.…”

Section: Introductionmentioning

confidence: 99%

“…This coating leads to compatibility issues with commonly used binder components in propellant formulas, specifically hydroxy-terminated polybutadiene (HTPB). , Furthermore, the low melting point (450 °C) of B 2 O 3 leads to the formation of a viscous liquid during combustion, hindering the transfer of oxygen to inner boron. The high boiling point (2065 °C) makes it difficult to evaporate, resulting in longer ignition delay times and incomplete combustion. , Additionally, the presence of HOBO species has been observed in the combustion products of boron, which may indicate incomplete release of the heat of combustion of B. , …”

Section: Introductionmentioning

confidence: 99%

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Synergistic Enhancement on Ignition and Combustion Properties of Boron via Viton Core–Shell Coating

Liu,

Wang,

Zhao

et al. 2024

Langmuir

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The high gravimetric (58.74 kJ/g) and volumetric (137.45 kJ/cm3) heat values loaded in boron (B) offer significant potential for application in solid propellants and explosives. However, the high melting (2076 °C) and boiling (3927 °C) points of boron powder and the low melting point (450 °C) of oxidation products affect the energy performance and application of boron. Fluorine-containing polymers have high oxidation potential and excellent mechanical properties and can produce expectant gaseous products through the combustion reaction with boron oxide, but research examining the interaction between purified boron powder and fluoropolymers and the optimal selection of the fluoropolymer remains scarce. Herein, the binding energy between typical fluoropolymers [Viton, polyvinylidene fluoride, poly(vinylidene fluoride-co-chlorotrifluoroethylene), and vinylidene fluoride] and boron was calculated via molecular dynamics simulations, which shows that Viton is an appropriate candidate for coating boron powder. In the experiment, The Bw@Viton core–shell composites were prepared using Viton as the coating layer, and boron powder was pre-purified with acetonitrile. Its structure, thermal properties, ignition, and combustion characteristics were then characterized. The results revealed successful removal of the oxide layer, and the hydrophobicity was significantly improved after Viton coating. Purification and coating synergistically enhance the energy release of boron powder, and the composites demonstrated excellent thermal, ignition, and combustion performances. In particular, the heat of oxidation and heat of combustion were increased by 26.6 and 32.7%, respectively. The ignition delay time was reduced by 53.2% compared to raw boron. A prospective reaction mechanism between boron and Viton is thus proposed.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synergistic Enhancement on Ignition and Combustion Properties of Boron via Viton Core–Shell Coating

Liu,

Wang,

Zhao

et al. 2024

Langmuir

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Preparation and characteristics of boron‐based composite micro‐units encapsulated by potassium perchlorate

Qin,

Liu,

Zeng

et al. 2024

Propellants Explo Pyrotec

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To improve the ignition and combustion performance of boron (B), the B@ potassium perchlorate (KP) composite micro‐units are successfully prepared by recrystallization of solvent evaporation. The morphology and structural composition show that B@KP composite micro‐units are formed by the gentle recrystallization of KP at the heterogeneous interface between B particles and solvents. It is shown by thermal analysis that the initial thermal decomposition temperature of KP is reduced by 49 °C due to the reduction of particle size. In addition, the heat of 420 J/g released by the thermal decomposition of KP is beneficial to the evaporation of the oxide boron (B2O3) film on the surface of B, which reduces the initial oxidation temperature of B by 185 °C and improves the ignition performance of B. Interestingly, the oxygen (O2) released by the thermal decomposition of KP quickly reacts with B to release heat of 3608 J/g, which improves the combustion performance of B. The optimal mass ratio of B to KP is 1: 5, which results in the ignition delay time of 641 ms, a reduction of 19 ms compared to the physical mixed sample. The ignition delay times of other samples are 724 ms, 680 ms and 650 ms respectively, and B could not be ignited successfully. In the combustion process, all samples emit a bright green flame of B combustion, and even a fierce combustion flame like a mushroom cloud appears. In a word, the B@KP composite micro‐units have great potential for application in solid propellants.

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Construction of Fe Nanoparticles Interfacial Layer on Micron Al Surface: Boosting the Efficient Energy Release of High‐Energy DAP‐4 as a Gradient Catalyst

Kou,

Lu,

et al. 2024

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The high‐energy (H2dabco)[NH4(ClO4)3] (DAP‐4) with excellent energetic performance attracts wide attention from researchers. The investigation of its interaction with the Aluminum (Al) is of great importance. However, the higher ignition threshold of DAP‐4 and the dense oxide layer (Al2O3) of Al severely limit the energy release efficiency of Al/DAP‐4. In this study, a new idea to is first proposed to improve and adjust the thermal decomposition and combustion performance of Al/DAP‐4 by constructing a highly dispersed iron (Fe) nanoparticle interfacial layer. It acts as a gradient catalyst to promote the thermal decomposition and combustion of DAP‐4 and Al, and it also act as an oxygen transport channel to promote the contact and reaction of oxidizing gases with the internal reactive Al powder. It reduces the thermal decomposition temperature of Al@Fe‐3/DAP‐4 from 386.30 °C (Al/DAP‐4) to 349.48 °C and leads to the vigorous combustion. Theoretical calculations show that Fe nanoparticle interfacial layer can facilitate the transport of oxygen through the established oxygen transport channels, and it can also significantly improve the energetic properties of Al@Fe‐3/DAP‐4 composites. In conclusion, the new approach is proposed to improve the performance of metal fuel/oxidizer composites by constructing interfacial layers, which is expected to promote their practical applications.

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Dual-core–shell structure B@LiF@AP with multi-effect synergies to improve processibility and energy release characteristics of B

Abstract: Boron (B) is the most suitable fuel for rocket ramjet. However, boron oxide (B2O3) on the surface of B causes many problems in application. B2O3 will cross-link with hydroxyl prepolymer,...

Cited by 15 publications

References 46 publications

Synergistic Enhancement on Ignition and Combustion Properties of Boron via Viton Core–Shell Coating

Synergistic Enhancement on Ignition and Combustion Properties of Boron via Viton Core–Shell Coating

Preparation and characteristics of boron‐based composite micro‐units encapsulated by potassium perchlorate

Construction of Fe Nanoparticles Interfacial Layer on Micron Al Surface: Boosting the Efficient Energy Release of High‐Energy DAP‐4 as a Gradient Catalyst

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