Abstract:

Abstract:To reduce the erosion of R2 high-energy propellant， a new composite erosion inhibitor based on silicon/modified nano TiO₂/paraffin was designed and prepared. The erosion-reducing performance of the new type of composite erosion inhibitor was studied by a semi-closed bomb test with the standard erosion inhibitor as the reference material. The erosion inhibition mechanism of the new composite erosion inhibitor was studied by scanning electron microscope-energy dispersive spectrum （SEM-EDS）， and its effect on the static combustion property of propellant was investigated using a closed bomb test. The results show that the new composite erosion inhibitor has a significant effect on reducing erosion. The erosion inhibition rate can reach 34.24% when the addition of erosion inhibitor is 5%. Decamethylcyclopentasiloxane （D5） in the erosion inhibitor is decomposed at high temperature， and the silicon oxide nanoparticles produced by the decomposition can effectively block the carburization reaction by adhering to the inner wall of the erosion tube. Since R2 propellant added with the new composite erosion inhibitor has higher combustion progressivity， the energy is released at the later stage of combustion which is beneficial to reduce the erosion.

Abstract:In order to study the corrosion inhibition characteristics and action mechanism of octaphenyl cage polysesquioxane （OPS） in the propellant， nitramine propellant samples with OPS content of 2%， 5%， 8% and control samples with no OPS were prepared. The ablation characteristics， combustion characteristics and energy properties of the propellant were studied using a semi-closed explosive device， a closed explosive device and an oxygen bomb calorimeter. The compatibility of OPS with nitramine propellant was studied by a differential scanning calorimeter （DSC）. The microstructure， element distribution and product composition of the inner surface of the ablative tube were characterized by scanning electron microscopy （SEM） and energy dispersive spectroscopy （EDS）. The results showed that OPS had good compatibility with nitramine propellant. When the OPS content was 5% and 8%， the ablation reduction rate was 23.9% and 36.0%， respectively. With the increase of OPS content， the ablation reduction rate gradually increases， while the energy and work ability of the propellant are reduced. The analysis of cracks， products and their distribution on the inner surface of the ablative tube showed that SiO₂ generated by OPS at high temperature was uniformly distributed in the inner layer of the tube wall， forming a protective layer with excellent thermal resistance characteristics， and reducing the erosion and scouring effect of high temperature gas and solid particles on the tube wall.

Abstract:Oblate spherical propellant is the main charges for small and medium caliber and light weapons， and the method of controlling its progressive properties has consistently been a hot research topic. The ethyl cellulose （EC）-coated microporous gun propellant was developed by combining internal microporous combustion enhancement using SC-CO₂ and the surface coating flame retardant via fluidized bed coating， resulting in precise and controllable energy release. Scanning electron microscopy and infrared spectroscopy were applied to investigate the microstructure and composition， and the closed bomb device was used to analyze the combustion and storage performance. The results showed that the coated microporous gun propellant exhibited surface structural integrity and density. The mass fraction of the coating layer increased from 2.32% to 9.79% when the coating time was increased from 5 min to 30 min， and the corresponding film thickness increased from 7 μm to 33 μm. Compared with the original gun propellant， the initial and maximum activities L₀ and L_m of the microporous gun propellant with 10 min coating time were reduced by 62.34% and 55.61%， respectively， with an A_L-B characteristic value of 1.304 MPa^-1·s^-1. Accelerated aging tests showed minimal changes in the combustion performance of the coated spherical propellant. The p-t and L-B curves of the aged samples were consistent with those of the untreated samples after aging at 75 ℃ for 14 days. This indicated that the EC-coated microporous gun propellant exhibits excellent storage stability.

Abstract:DA-propellant is a high-energy and low erosion propellant independently developed in China. It has the characteristics of high energy， low detonation temperature， good combustion cleanliness， and low smoke residue. This article summarizes the research on the synthesis and application azidenitroamine， formulation and performance of DA-propellant， manufacturing process， surface treatment， charge application， and testing methods. It also highlights that there are deficiencies in certain basic theoretical aspects and limited research on environmental adaptability of DA-propellant. Developing green， low-cost synthesis methods and mastering DIANP process amplification technology are effective ways to enhance competitiveness. It is also believed that the development of DA-propellant requires a combination of basic research and practical applications to promote the development of high-energy and low ablation characteristic materials in the industry.

Abstract:As the functional unit to achieve the shooting and precise destruction of barrel weapons， the gun propellant holds a key and core technology status. In this paper， the development histories and evolutionary patterns of the gun propellant and charge technology were systematically summarized and analyzed. The research status and main problems were described across three levels： science， technology and products. Meanwhile， the future development trends of the gun propellant and charge technology were analyzed and prospected in terms of scientific exploration， technological innovation， and the application of products in weapon systems. This paper aims to provide reference for gun propellant researchers， industry management， and manufacturing companies to promote the industry"s healthy development.

Abstract:A semi-closed bomb experiment was designed to construct a system for evaluating the erosion performance of propellant according to actual requirements. A transient numerical simulation model was established based on the geometric dimensions of the erosion tube and the measured p-t curve. The relationship between the transient erosion rate model parameters and the total mass loss of erosion tube was established through the space-time distribution of wall temperature of the erosion tube. Based on the mass loss of the semi-closed bomb experiment， the parameters of erosion reaction were optimized by particle swarm algorithm. The results showed that both the temperature of the interface between the propellant gas and the erosion tube wall and the growth rate of melting depth decreased with the increase of erosion time. The 45^# steel and double base powder （Shuang-fang 3） were selected as the material sample and propellant sample. The optimized pre-factor and apparent activation energy values were 0.3403 s^-1 and 134.6 kJ∙mol^-1， respectively. At this time， the value of loss function was only 3.0×10^-6. Thus， the transient erosion rate model is a promising tool to evaluate the erosion status of the barrel weapon.

Abstract:In order to investigate the application of the fuzzy comprehensive evaluation model in the modification evaluation of high energy nitramine gun propellant， the triamino trinitrobenzene （TATB） coated and polyester （NA） coated gun propellant were prepared by coating technology using TATB and NA as the burning rate reduction materials， and their bulk densities， burning rates， explosion heats， propellant burning progressivities and interior ballistic performances were compared. Moreover， the analytic hierarchy process （AHP） was adopted to quantify the influence of TATB and NA on the basic characteristics and the combustion performances above. It was found that， the fuzzy comprehensive evaluation can be established between the basic characteristics and combustion performances of propellants. For the better overall combustion performance， the weight of burning rate is equal to 0.82， which is the highest； the weights of explosion heat and bulk density are equal to 0.11 and 0.07， respectively. In the case of small difference in bulk density， even though the energy loss caused by NA coating is greater than that of TATB coating， the decrease of burning rate by NA coating would be larger and the propellant coated with NA has the better performance than the propellant coated with TATB， and the two are significantly better than that of blank propellant

Abstract:Three cyclodextrin metal-organic framework （CD-MOF） materials were successfully synthesized using the vapor-diffusion method. The structures were analyzed via single-crystal X-ray diffraction. As potential flame suppressants， the three CD-MOFs exhibit lower thermal decomposition temperatures （250-300 ℃） than traditional potassium nitrate （722.0 ℃）， allowing for potassium ion to release more easily. The good physical dispersibility and chemical compatibility within nitrocellulose （NC） are also demonstrated. Additionally， the NC containing CD-MOF produces fewer flammable and harmful gases （CO， NO， NO₂， and N₂O） during thermal decomposition. The single base propellant containing γ-CD-MOF shows the smallest flame area during combustion （119.6 mm²）. In comparison， the single base propellant containing β-CD-MOF exhibits the lowest standard deviation in the flame area （8.4 mm²）， indicating more consistent flame suppression performance. In contrast， the single base propellant containing KNO₃ displays the largest flame area （392.7 mm²）.

Abstract:Nitro gradiently distributed propellant （NGDP）， as a new type of propellant， has the characteristics of high oxygen balance， less harmful for use， and anti-migration. To analyze the thermal hazard of denitration reaction in the preparation process of NGDP， the exothermic process during the denitration reaction and the thermal decomposition behavior of the material， the reaction was measured by reaction calorimeter （RC1mx）， differential scanning calorimeter （DSC） and accelerated adiabatic calorimeter （ARC）. The results showed that the exothermic amount of the denitration reaction was 61.46 kJ， and the adiabatic temperature rise （ΔT_ad） of the reaction system calculated from this was 58.28 ℃. In the DSC test， the denitration treatment increased the decomposition temperature of the double base propellant from 191.33 ℃ to 194.16 ℃. Based on the ARC test data of the post-reaction system， the relationship between the Time to Maximum Rate （TMR_ad） and the temperature was calculated. When the adiabatic induction period is 24 hours， the corresponding T_D24 is 137.2 ℃. The T_D24， maximum technical temperature （MTT）， and maximum temperature of the synthesis reaction （MTSR） of the reaction are 137.2 ℃， 108 ℃， and 128.52 ℃， which means that the system had the risk of spraying in case of cooling failure. However， the risk of triggering the secondary decomposition reaction was low.

Abstract:In order to investigate the thermal erosion characteristics and variation law of triple base propellant， various kinds of gun propellants with different components content were prepared. The erosion characteristics were determined through simulated test in a semi-closed bomb. The analysis reveals the impact of energy component and plasticizer content on gun propellant explosion temperature， and the impact of explosion temperature on erosion characteristics. The results indicate that changes in the explosion temperature of gun propellant， attributed to variations in cyclotrimetheylenetrinitramine （RDX）， nitroguanidine （NQ） and dioctyl phthalate （DOP） content， significantly affect erosion characteristics. An increase of 1% in RDX content results in an increase in explosion temperature by 0.59% and an increase in erosion rate by 1.23%. Compared with the absence of RDX， the erosion rate of 2% RDX-containing propellant increase 23.38%. Notably， an increase of 1% in NQ content reduces the explosion temperature by 0.23% and the erosion rate by 0.56%. An increase of 1% in DOP content reduces the explosion temperature by 2.99% and the erosion rate by 7.01%. For the triple base propellants within the range of explosion temperature from 2600-3100 K， an exponential relationship between the rate of erosion mass and explosion temperature is established， and characteristic coefficients of RDX， NQ， DOP system is given respectively， which is 0.106， 0.101， 0.163.

Abstract:To adapt to the operational requirements of the wide temperature range environment for the single-based propellant， this work investigated the modification effects of temperature coefficient of propellant through physical structure modification， insensitive technology， and surface modification methods. Here， the prepared propellant was evaluated by the internal ballistic performance test. The low temperature velocity temperature coefficient and high temperature chamber pressure temperature coefficient could be controlled below 5% and 10%， respectively when the propellant was modified with 5% pore extender， a particle size of energetic solid material of 55 μm， the insensitive agent MA， and surface sensibilization modification. The modification mechanism for the propellant towards these methods is attributed to that the pores， irregular bulge， open interface， and zipper hole section structure are formed. Hence， at the lower temperature condition， because of the porous layer and PMA of the propellant becoming brittle， the impact resistance-being weakened， the fracture tendency of the pores and the interface being increased， the initial burning surface of the propellant was increased at low temperature. At the lower temperature condition， because of the closed hole phenomenon of the propellant blocked （closed） hole layer being intensified， insensitive agent being expanded and squeezed into the hole， the impact resistance being enhanced， the fracture tendency of the pore and the interface being reduced， the initial burning surface of the propellant was reduced under high temperature conditions. Through the compensation of the burning rate， the aim of adjusting the temperature coefficient of the propellant is achieved.

Abstract:

Abstract:In order to explore the application prospect of a novel azido plasticizer 1，5-diazide-3-oxapentane （AZDEGDN） in gun propellant formulation， a semi-solvent method was adopted to prepare double- and triple-base gun propellants using AZDEGDN as the plasticizer， and the morphology， density as well as static combustion performance at different temperatures of AZDEGDN-containing propellants were studied. Results show that the AZDEGDN-containing double-base propellant （ADG-2） and triple-base propellant （ADG-3） without obvious defects in appearance can be prepared by semi-solvent extrusion process. SEM test shows that solid additives hexogen （RDX） and nitroguanidine （NGu） are uniformly distributed within ADG-3 propellant. The density of ADG-2 is 1.44 g·cm^-3 and ADG-3 is 1.52 g·cm^-3， both close to their theoretical density， indicating that the internal structures of AZDEGDN-containing propellants are relatively dense. The closed vessel tests demonstrate that the static combustion performances of both ADG-2 and ADG-3 propellants at room temperature （20 ℃） are stable. The burning rates increase evenly with the increase of pressure， without obvious turning phenomenon in burning rate-pressure curves （u-p curves）. The maximum combustion pressure of ADG-2 and ADG-3 propellants is 237.71 MPa and 263.80 MPa， and the burning rate pressure index is 0.9098 and 0.9754， respectively. The addition of RDX and NGu results in an increase of 15.5% and 10.9% in the burning rate pressure index of AZDEGDN-containing propellants in the low pressure range （50-100 MPa） and medium pressure range （100-150 MPa） respectively， while the burning rate pressure index in the high pressure range decreases by 4.2%. At high temperature （50 ℃） and low temperature （-40 ℃）， ADG-3 propellant can still keep stable combustion. The maximum combustion pressure changes from 263.80 MPa at room temperature to 265.92 MPa and 261.13 MPa， respectively. Besides， the combustion time changes from 14.70 ms to 13.52 ms and 16.40 ms respectively， and the burning rate pressure index changes from 0.9754 to 0.9464 and 0.9938 respectively. It is concluded that AZDEGDN-containing gun propellant is simple and mature in preparation method， dense and defect-free in structure， and also stable in static combustion performance， which is expected to become a kind of novel low-ablation gun propellant.