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In order to break through the top-down combustion mode brought by the traditional pillars, it is explored to explore the exploration of delay composition array construction in two-dimensional dimensions. In this study, B-CuO, B-Bi2O3, B-Fe2O3 sticks and combustion networks with good forming properties were prepared with the help of a micro-pen direct ink writing device by dispersing the above materials in DMF with boron and metal oxides as the main body of the charge and F2602 as the binder. The sticks were thermally ignited using a nichrome wire, and the flame propagation behaviors of the sticks with different formulations, spacings and heights were tracked with a high-speed camera, and a series of combustion networks were designed on the premise of not leaping into flames. Results show that the B-CuO stick has the fastest ignition speed level (19.71-29.02 mm ⋅ s-1) at equivalence ratios of 1.0-4.0, followed by B-Bi2O3 (5.99-16.01 mm ⋅ s-1) and B-Fe2O3 is the slowest (1.91-4.94 mm ⋅ s-1). The sticks burned best at an equivalence ratio of 1.0-1.5. A variety of combustion networks were constructed on 50 x 50 mm glass slides by selecting B-CuO, B-Bi2O3, and B-Fe2O3 at the equivalence ratios of 1.0, 1.5, and 1.5, respectively, among which B-CuO had the shortest combustion time (5.17 s), the shortest total combustion network length (252 mm), and 400 mm network could be realized for B-Bi2O3. Construction and 19.85 s, and B-Fe2O3 can realize 608 mm network length and 130.7 s combustion time. Through these studies, the two-dimensional combustion network construction of boron-metal oxides was realized, which provides a new idea for the delay action in small size. [ABSTRACT FROM AUTHOR]

To explore the composite process of B–CuO and B–Bi2O3 two-component laminated sticks, obtain the corresponding sticks with good printing effect, and explore the energy release behavior. In this study, boron, copper oxide, and bismuth trioxide powders were dispersed in the dispersed phase (DMF) using F2602 as a binder, and the construction of two-component B–CuO, B–Bi2O3, three-component micro-composite, and three-component macro-composite sticks were realized with the help of double nozzle direct ink writing (DIW) technique respectively. The resulting sticks were ignited by a nichrome wire energized with a direct current, and a high-speed camera system was used to record the combustion behavior of the sticks, mark the flame position, and calculate the rate of ignition. The results showed that the B–CuO stick burning rate (42.11 mm·s−1) was much higher than that of B–Bi2O3 (17.84 mm·s−1). The formulation with the highest CuO content (ωCuO = 58.7%) in the microscale composite of the sticks also had the fastest burning rate of 60.59 mm·s−1, as the CuO content decreased (ωCuO = 43.5%, 29.3%), its burning rate decreased to 34.78 mm·s−1, 37.97 mm·s−1. The stick with the highest copper oxide content (ωCuO = 60%) also possessed the highest burning rate (48.84 mm·s−1) in the macro-composite sticks, and the burning rates of the macro-composite sticks with component spacing of 0.1 mm, 0.2 mm, and 0.5 mm were 43.34 mm·s−1, 48.84 mm·s−1, and 40.76 mm·s−1.

To explore the composite process of B-CuO and B-Bi2O3 two-component laminated sticks, obtain the corresponding sticks with good printing effect, and explore the energy release behavior. In this study, boron, copper oxide, and bismuth trioxide powders were dispersed in the dispersed phase (DMF) using F2602 as a binder, and the construction of two-component B-CuO, B-Bi2O3, three-component micro-composite, and three-component macro-composite sticks were realized with the help of double nozzle direct ink writing (DIW) technique respectively. The resulting sticks were ignited by a nichrome wire energized with a direct current, and a high-speed camera system was used to record the combustion behavior of the sticks, mark the flame position, and calculate the rate of ignition. The results showed that the B-CuO stick burning rate (42.11 mmªs -1) was much higher than that of B-Bi2O3 (17.84 mmªs-1). The formulation with the highest CuO content (ωCuO = 58.7%) in the microscale composite of the sticks also had the fastest burning rate of 60.59 mmªs -1, as the CuO content decreased (ωCuO=43.5%, 29.3%), its burning rate decreased to 34.78 mm$s -1, 37.97 mmªs -1. The stick with the highest copper oxide content (ωCuO = 60%) also possessed the highest burning rate (48.84 mm$s -1) in the macro-composite sticks, and the burning rates of the macro-composite sticks with component spacing of 0.1 mm, 0.2 mm, and 0.5 mm were 43.34 mm$s -1, 48.84 mmªs -1, and 40.76 mmªs -1. [ABSTRACT FROM AUTHOR]

In the past few years, we have witnessed that due to the pandemic and wars, some countries have limited their export of various ingredients. The request has been made to create a time delay pyrotechnic composition with easily accessible ingredients. For that purpose, black powder with addition of phenol formaldehyde resin was a possible solution. This study aims to show an optimization of the ratio in the fuel-oxidant mixture and how this ratio influences the properties of pyrotechnic compositions. The stoichiometric ratios were determined by using the oxygen balance (OB) and pyro valence (PV) values. The linear burning rate was measured using a VOD 811 measuring system for some typical compositions which were pressed into alluminium tubes. The calorimetric bomb was used in the experiments with an inert gas supply to determinate the heat of reaction and the closed-vessel test was used to measure the production of gaseous products. The theoretical maximum density was calculated using ingredients' density measured with gas pycnometer ULTRAPYC 5000 with an inert gas supply nitrogen or helium. After these tests, it was concluded that pyrotechnic composition with more than 25 wt.% of charcoal does not satisfy requirements for a gas producing pyrotechnic composition. The minimal requirements can be satisfied with pyrotechnic compositions that consist of 75-80 wt.% of potassium

Azidodeoxycellulose (AC) is evaluated in a closed vessel as part of a propellant formulation containing nitrocellulose (NC) and nitroglycerin (NG) as binders. It is found that the AC systematically generates greater pressure and a faster linear burning rate when compared to a formulation having a similar concentration of a mixture of cellulose and NC that is meant to replicate a comparable substitution degree. An additional finding is that a formulation containing 13%wt of AC generates higher pressure in a closed vessel than the mixture of NC and NG alone. These results are evidence that AC is an adequate solid filler for propellant formulations. [ABSTRACT FROM AUTHOR]

Mainly the purpose of this research is to increase the oxidation efficiency of boron powder as well as to accelerate the decomposition of AP by carrying out the trials of several metals with boron-based and AP-based propellants. B/Mg, B/Al, B/Ni, B/Fe and B/Mo composites are prepared by employing ball milling method. The thermal analysis of doped boron powder with Fe and Mo shows the better activity and reaction performance. Then, the solid propellant (SP) is kneaded within proposed proportions of B/Metal composites, HTPB and AP. The B/Metal composites have improved the combustion performance of SP in air, notably in closed bomb and these had an obvious accelerating effect on the thermal decomposition of SP, especially B/Fe. The burning rates of SP/B/Fe in air and closed bomb are 60.4 and 139% faster than that of SP, respectively. Furthermore, B/Fe changed the decomposition process of AP and dropped in the peak temperature due to Fe-promoting effect. The multiple oxidation states enable Fe to be an attractive candidate as a dopant in propellants, which exhibits superior activity in the oxidation of B and decomposition of AP. [ABSTRACT FROM AUTHOR]

The performance of the extruded cord geometry of nitrocellulose (NC) propellants plasticized by glycidyl azide polymer (GAP) and nitroglycerine (NG) has been evaluated using both closed and erosion vented vessel techniques in order to obtain the linear burning rate and the relative erosivity of these propellants. The closed vessel experiments performed at −46, 21 and 63 °C demonstrate that the measured maximum pressure is in accordance with the calculation obtained using the CHEETAH V2 thermochemical code. From the closed vessel analysis, the linear burning rates show that it is on average 89±3 % that of the 21 °C propellant when fired at −46 °C. and 112±4 % when fired at 63 °C. The addition of either GAP or NG increases the linear burning rate when compared to the neat NC formulation. Relative erosion data obtained in the erosion vented vessel are in agreement with the Arisawa‐Kimura models and it is found that the ratio of CO/CO2 concentration in combustion gases is a better erosivity indicator than N2/CO ratio. [ABSTRACT FROM AUTHOR]

• The powder integration of B/KNO 3 was realized using DIW. • The reactivity of B/KNO 3 micro-energetic stick has a size effect. • The reactivity of energetic stick can be significantly enhanced using architectures. Boron/potassium nitrate (B/KNO 3 , BPN) is a promising intermolecular energetic complex with a high calorific value. The powder integration and reactivity regulation mechanism of BPN-based composite on the integrated state have not been revealed. In this study, the BPN/PVDF energetic sticks with good forming performance were prepared through a direct ink writing (DIW) device with polyvinylidene fluoride (PVDF) as the polymer skeleton. Furthermore, the energetic sticks were ignited by a Joule-heated Ni-Cr wire, and the flame propagation behaviors of energetic sticks with different BPN loading, fuel/oxidant ratios, and physical sizes were tracked using a high-speed camera. Additionally, the energy coupling behavior of architectures with different channel widths was studied. The results show that when BPN loading decreases, the linear burning rate of energetic sticks shows a trend of first rapid and then slow decrease, and the burning rates reduce from 125.59 to 28.36 mm/s. When the BPN loading is certain, the slightly fuel-rich formulation (20–30 wt% B content) has the highest burning rate. The energetic sticks have an obvious size effect: when the thickness is less than 110 μm, the combustion cannot propagate stably, and when the thickness is between 750 and 1400 μm, the burning rate–thickness curve shows a plateau. For simple architectures, the burning rate is related to the channel width. When the channel width of the structure reaches 0.2–0.5 times the width of the stick, the burning rate (∼240 mm/s) is about 3 times that of the architecture without channels (∼80 mm/s). Through these studies, we realized the powder integration of the BPN combination and provided a reference for the chemical reaction regulation and the multifunctional applications of BPN sticks. [ABSTRACT FROM AUTHOR]

A new device for measuring the linear burning rate of liquid propellants at high pressures is reported. High-pressure environments were generated by the combustion of solid propellants. The coated propellants, which burn progressively, were introduced to maintain the approximate constant-pressure environments. By use of ion probe transducers, measurements were made of the spread velocity of the flame surface, i.e. the apparent linear burning rate of the HAN-based liquid propellant LP1846 (HAN =hydroxylammonium nitrate) was measured quantitatively at pressures from 6 to 28 MPa. The results show that it follows the exponential burning rate law. The burning rate coefficient and exponent were fitted by least-squares methods. Based on the experiment, a simplified model of the linear burning rate of HAN-based liquid propellants at high pressures was developed. The numerical simulation is found to be in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

This paper considers the mechanisms involved in the effect of the unconnected porosity of the condensed phase of nitrocellulose propellants on the linear burning rate with a pressure rise. A model based on experimental data is proposed for the variation in the linear burning rate taking into account the compaction of the fuel cells resulting in a nonlinear dependence of the burning rate on pressure. The temperature coefficient of the linear burning rate is found to exhibit a nontrivial behavior under pressure rise conditions in various ranges of initial temperatures. [ABSTRACT FROM AUTHOR]