Binder melt: Quantification using SEM/EDS and its effects on composite solid propellant combustion

Kumar, Navneet; Vijay, Chaitanya; Ramakrishna, P. A.

doi:10.1016/j.proci.2018.06.003

Cited by 13 publications

(13 citation statements)

References 8 publications

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“…Recent studies on MICs have shown that reducing component size, , enhancing the contact between fuels and oxidizers, − and/or increasing the ignitibility of the fuels − enhance their reactivity. Loose powders must ultimately be manufactured into free-standing architectures by incorporating different types of binders or architectures for any realistic application. − Unfortunately, the incorporation of these energetic materials into dense structures can also inhibit their performance since their combustion becomes limited by binder decomposition and phase transitions, − ultimately leading to order-of-magnitude changes in the burn rate. , This leads to even more parameters to balancebinder materials must be employed to make the materials safe and avoid accidents but must be used in as little quantity as possible to retain their potential energy release. ,− …”

Section: Introductionmentioning

confidence: 99%

Carbon Fibers Enhance the Propagation of High Loading Nanothermites: In Situ Observation of Microscopic Combustion

Wang

Kline

Rehwoldt

et al. 2021

ACS Appl. Mater. Interfaces

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A major challenge in formulating and manufacturing energetic materials lies in the balance between total energy density, energy release rate, and mechanical integrity. In this work, carbon fibers are embedded into ∼90 wt % loading Al/CuO nanothermite sticks through a simple extrusion direct writing technique. With only ∼2.5 wt % carbon fiber addition, the burn rate and heat flux were promoted >2×. In situ microscopic observation of combustion shows that the carbon fiber intercept ejected hot agglomerates near the burning surface and enhanced heat feedback to the unreacted material. This study outlines how these approaches may enhance the propagation and reduce the two-phase flow losses.

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Section: Introductionmentioning

confidence: 99%

Carbon Fibers Enhance the Propagation of High Loading Nanothermites: In Situ Observation of Microscopic Combustion

Wang

Kline

Rehwoldt

et al. 2021

ACS Appl. Mater. Interfaces

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“…In recent years, some studies have found that adjusting propellant formulation can also improve the agglomeration characteristics of aluminum particles. For example, increase the concentration of ammonium perchlorate(AP, NH 4 ClO 4 ), reduce the metal content, change the RDX content [19], introduce catalyst [20] or adjust the performance of binder [21,22] to ameliorate the combustion and agglomeration characteristics of propellant. Researchers have also found that the addition of new materials has a significant impact on the agglomeration of aluminum particles.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation on Combustion Characteristics and Agglomeration of Al/NEPE Propellants

Zhang

Feng³

et al. 2021

Propellants Explo Pyrotec

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In order to understand the ignition and combustion characteristics of NEPE propellants under different pressure conditions and the agglomeration behavior of aluminum particles on the burning surface, the Al/NEPE propellant was tested on a sealed high-pressure laser ignition platform. Laser ignition experiments show that both ignition delay time and combustion time are inversely proportional to ambient pressure. With the increase of pressure, the reduction of ignition delay time and self-sustaining combustion time is reduced. The impact of pressure on ignition and combustion is very complex. We then analyze the effect of pressure on ignition delay time using a theoretical mechanism. High-speed microscopic images display the agglomeration of aluminum particles in propellants mainly through the following three processes: accumulation, aggregation, and agglomeration. It is also found that many aluminum particles are agglomerated on the surface, the aluminum droplet agglomerates formed on the combustion surface are separated from the combustion surface, and the agglomerates rupture and flow out of the liquid alumina during the combustion process. The phenomenon of secondary agglomeration is also observed. The microstructure and elemental composition of combustion products of aluminum particles in NEPE propellant were obtained by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The detection results confirmed some agglomeration phenomena. At 3.0 MPa, the combustion of the propellant sample is sufficient, and the aluminum particles are smooth spherical alumina particles. At 1.0 MPa, the combustion of the propellant sample is insufficient, and the aluminum particles are rough. The particle size under different pressure was analyzed by a laser particle size analyzer. The results show that increasing the pressure can reduce the average agglomeration size of aluminum particles and improve combustion efficiency. The number of large particle aggregates is more at 3 MPa. From the perspective of overall particle size results, within the same diameter interval, the percentage of particle number does not increase or decrease significantly with the increase of pressure.

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“…The mechanism of BRSs is complicated [47], but all of them work out by shifting the equilibrium of AP dissociation to the left. However, the mechanism research used to focus on their influences on the decomposition and combustion of AP, some papers indicated that binders also had effects on the burning rate of propellants [48][49]. Thus, the influence of BRSs on binders may also need our attention.…”

Section: Discussionmentioning

confidence: 99%

A Review on the Use of Burning Rate Suppressants in AP‐Based Composite Propellants

Pang²,

Wang³

et al. 2021

Propellants Explo Pyrotec

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Ammonium perchlorate (AP) is the most widely used oxidant in composite propellants. Propellants based on AP usually have a high burning rate, but in some applications, it is necessary to have a slower burning rate. The functional additives, which can reduce the burning rate of propellants, were named coolants, burning rate suppressants (BRSs), burning rate depressants, or burning rate inhibitors. This paper introduced different types of BRSs, such as amide-based compounds, cyclic azines, quaternary ammonium salts, metal salts, etc., their mechanism and development in AP-based composite propellants. For organic amines, the burning rate trend is as follows: biuret < melamine < oxamide < urea < base. Cyclic azines are special organic amines which form large, thermally stable cyclic azines in addition to common low-molecular-weight gases NH 3 , CO 2 , HCN, and N 2 O when heated. With the smallest addition but the highest effect, quaternary ammonium salts will not reduce the specific impulse of the propellant, nor do they interfere with cure reaction or adversely affect the physical properties of the cured propellant. Metal salts reduce the burning rate by forming more stable substances than HClO 4 with AP. The mechanism of BRSs is complicated, but all of them can be explained based on AP deflagration. At last, the development trend of efficient BRSs was discussed, the preparation of liquid BRSs and the combination of AP bonding agents with BRSs were both first proposed, which worth further research in the future.

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Binder melt: Quantification using SEM/EDS and its effects on composite solid propellant combustion

Cited by 13 publications

References 8 publications

Carbon Fibers Enhance the Propagation of High Loading Nanothermites: In Situ Observation of Microscopic Combustion

Carbon Fibers Enhance the Propagation of High Loading Nanothermites: In Situ Observation of Microscopic Combustion

Experimental Investigation on Combustion Characteristics and Agglomeration of Al/NEPE Propellants

A Review on the Use of Burning Rate Suppressants in AP‐Based Composite Propellants

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