硝胺发射药燃速压力指数转折及其改善途径

综述了硝胺发射药燃烧方面的研究工作，从发射药配方研究角度总结了影响硝胺发射药燃速压力指数的一些基本因素，指出了改善硝胺发射药燃烧性能的一些有效途径；初步讨论了硝胺发射药燃烧改良剂的选择和使用。     

表面活性剂在发射药中的应用

采用密闭爆发器试验手段,对低易损性发射药的燃烧性能进行了研究。研究发现,硝胺颗粒的形状、颗粒度对发射药燃烧性能有较大的影响。化学重结晶处理的硝胺呈针状容易引起应力集中,不利于发射药燃烧性能的改善;球磨处理的硝胺呈鹅卵石状,有利于发射药燃烧性能。在配方组成及工艺参数完全相同的条件下,在一定范围内硝胺颗粒度越大。燃速越大,而且燃速压力指数也高;颗粒度减小。在一定程度上可以改善燃烧性能,但颗粒度减小到一定程度时。反而引起了高燃速压力指数的现象。用表面活性剂对细颗粒硝胺处理后,可以达到改善燃烧性能的目的。     

高能硝胺发射药物的膛内基本燃烧特征

针对高能硝胺发射药在静态下燃速压力指数大的特殊燃烧性能，通过３０ｍｍ高压模拟炮试验，采用与制式单基药相对比的研究分析方法，对高能硝胺发射药在火炮膛内条件下的基本燃烧特征进行了研究分析。     

高能硝胺发射药的膛内基本燃烧特征

针对高能硝胺发射药在静态下燃速压力指数大的特殊燃烧性能，通过３０ｍｍ高压模拟炮试验，采用与制式单基药相对比的研究分析方法，对高能硝胺发射药在火炮膛内条件下的基本燃烧特征进行了研究分析。     

硝胺发射药的压力指数与爆温的关系

指出硝胺发射药的燃烧性能问题，提出了研制综合性能优良的高能低烧蚀发射药的课题，使火药的爆温较低，而燃速压力指数小于１，同时解决了炮管的烧蚀问题。     

硝胺发射药的热行为与燃烧性能的关系

应用ＤＳＣ热分析技术，结合密闭爆发器测试结果，分析了各种制式发射药及硝胺发射药的热化学行为与燃烧性能之间的关系，研究了燃烧改良剂ＳＧ对热化学行为的影响及对改善硝胺发射药燃烧性能的贡献。     

梯度硝基发射药吸湿性研究

梯度硝基发射药作为一种新型能量释放渐增性发射药,其表面的硝酸酯基被还原为羟基。由于梯度硝基发射药表面羟基含量增加,在长期贮存过程中,环境湿度会对梯度硝基发射药燃烧性能产生影响。为了研究梯度硝基发射药的吸湿性,针对单孔药、七孔药和球扁药三种不同药型的梯度硝基发射药,采用平衡干燥器法研究了不同脱硝工艺梯度硝基发射药的吸湿性,探索了吸湿性对三种不同药型梯度硝基发射药燃烧性能的影响。结果表明,随着脱硝试剂浓度和反应温度的增大,梯度硝基单孔药的吸湿率增加。在环境湿度为90.26%,梯度硝基单孔药、梯度硝基七孔药和梯度硝基球扁药的吸湿率分别为2.52%、2.71%和1.56%。吸湿前后三种梯度硝基发射药燃烧性能测试表明,吸湿后三种梯度硝基发射药的最大燃烧压力较吸湿前均有所降低,但吸湿后的梯度硝基发射药仍然具有能量释放的高渐增性。     

高性能改性单基发射药的制备与性能

以高氮量单基发射药为原料,使用先吸收NG、后吸收聚酯钝感剂的两步法工艺,成功制备出高能钝感单基药（HEDS）。试验表明,对比单基发射药,HEDS发射药的能量更高,燃烧渐增性更强,吸湿性更小。随NG加入量增大,钝感剂加入量减小,HEDS发射药的爆热增大。HEDS发射药具有十分优异的燃烧渐增性能,且钝感剂含量对其燃烧渐增性有显著影响,这种特性与其特殊结构有关。HEDS发射药的点火性能有待改进。     

四种硝胺发射药燃烧规律研究

通过密闭爆发器恒压燃速仪对四种硝胺发射药在５０－４００ＭＰａ压力范围的燃速测定，分析了它们的燃烧规律，发现在黑索今基硝胺发射药中，除加入硝基胍作为燃速改良剂外，另一种化合物的加入。更有效地改善了黑索今基硝胺发射药ｕ－ｐ曲线转折的程度，并使压力指数控制在１。００左右。     

新型高能高强度JMZ发射药的燃烧特性

为探索混合硝酸酯增塑的聚醚聚氨酯黏合剂体系的新型发射药的燃烧性能,通过密闭爆发器常规实验和高压实验．研究分析了JMZ发射药在不同压力范围的燃烧特性。结果表明,JMZ发射药在低压下的燃速压力指数较大,具有高含量RDX硝胺发射药的共同特征,但在高压下的燃速压力指数逐渐变小,与制式发射药相当,在燃速压力指数的变化过程中不存在明显的转折现象。另外,JMZ发射药在起始阶段表现出了良好的燃烧渐增性,对身管武器的应用是十分有利的。     

Burning Characteristics of Ammonium Nitrate‐based Composite Propellants Supplemented with Ammonium Dichromate

Ammonium nitrate (AN)‐based composite propellants have attracted much attention, primarily because of the clean burning nature of AN as an oxidizer. However, such propellants have some disadvantages such as poor ignition and low burning rate. Ammonium dichromate (ADC) is used as a burning catalyst for AN‐based propellants; however, the effect of ADC on the burning characteristics has yet to be sufficiently delineated. The burning characteristics of AN/ADC propellants prepared with various contents of AN and ADC have been investigated in this study. The theoretical performance of an AN‐based propellant is improved by the addition of ADC. The increase in the burning rate is enhanced and the pressure deflagration limit (PDL) becomes lower with increasing amount of ADC added. The increasing ratio of the burning rate with respect to the amount of ADC is independent of the AN content and the combustion pressure. The optimal amount of ADC for improving the burning characteristics has been determined.     

Thermal Decomposition Behaviors and Burning Characteristics of Ammonium Nitrate/Polytetrahydrofuran/Glycerin–based Composite Propellants Supplemented with MnO2 and Fe2O3

Although a polytetrahydrofuran (PTHF) blend with added glycerin as a crosslinking modifier is an effective binder for improving the performance of a propellant, a burning catalyst is required for the combustion of the ammonium nitrate (AN)/PTHF/glycerin propellant. MnO₂ and Fe₂O₃ are useful burning catalysts for AN‐based propellants. The thermal decomposition behaviors of the AN/PTHF/glycerin propellant supplemented with MnO₂ and Fe₂O₃ catalysts, and the catalytic effect of these catalysts on the burning characteristics was investigated in this study. The thermal decomposition behaviors of these propellants depended on the kind of catalyst used. The propellants containing MnO₂ burned above 4 MPa, while those containing Fe₂O₃ burned above 0.5 MPa. The burning rate increased in the order, (AN/PTHF/Fe₂O₃)<(AN/PTHF/MnO₂)<(AN/PTHF/MnO₂/Fe₂O₃). The improvement in the ignitability and burning rate was dependent on the kind of catalyst used. The burning characteristics of the AN/PTHF/glycerin propellants were improved by the combined effect of multiple catalysts with differing catalytic mechanisms, as compared to the propellant supplemented with any single catalyst.     

颗粒粘结高燃速推进剂燃速设计方法的研究

介绍了颗粒粘结高燃速固体推进剂的工艺特点,利用推进剂燃烧特征化学基团方法预估了几种小药粒和速燃粘结剂的燃速,提出了颗粒粘结高燃速固体推进剂燃速的设计方法.     

Burning Characteristics of Ammonium Nitrate‐based Composite Propellants Supplemented with MnO2

Ammonium nitrate (AN)‐based composite propellants have several major problems, namely, a low burning rate, poor ignitability, low energy, and high hygroscopicity. The addition of a burning catalyst proved to be effective in improving the burning characteristics of AN‐based propellants. In this study, the burning characteristics of AN‐based propellants supplemented with MnO₂ as a burning catalyst were investigated. The addition of MnO₂ is known to improve the ignitability at low pressure. The most effective amount of MnO₂ added (ξ) for increasing the burning rate is found to be 4 %. The increasing ratio with ξ is virtually independent of the burning pressure and the AN content. However, the pressure exponent unfortunately increased by addition of MnO₂. The apparent activation energy of the thermal decomposition for AN and the propellant is decreased by addition of MnO₂. From thermal decomposition kinetics it was found that MnO₂ could accelerate the thermal decomposition reaction of AN in the condensed phase, and therefore, the burning characteristics of the AN‐based propellant are improved.     

镁铝中能贫氧推进剂燃烧性能初探

系统地研究了镁铝中能贫氧推进剂的燃烧特性,并对该类推进剂的配方进行了初步的优化设计。研究发现,高氯酸铵含量和镁铝比对贫氧推进剂燃烧特性有显著影响。增加ＡＰ含量和金属添加剂中镁粉含量均有助于提高推进剂的燃速和拓宽其低压可燃极限。另外,采用超细组分或添加燃速催化剂也是提高推进剂燃速和拓宽低压可燃极限的重要途径。     

Ballistic Modification of Nitramine Propellants with Special Reference to NG‐PE‐PCP‐Based High Energy Propellants

The burning rate pressure relationship is one of the important criteria in the selection of the propellant for particular applications. The pressure exponent (η) plays a significant role in the internal ballistics of rocket motors. Nitramines are known to produce lower burning rates and higher pressure exponent (η) values. Studies on the burning rate and combustion behavior of advanced high‐energy NG/PE‐PCP/AP/Al‐ and NG/PE‐PCP/HMX/AP/Al‐based solid rocket propellants processed by a conventional slurry cast route were carried out. The objective of present study was to understand the effectiveness of various ballistic modifiers viz. iron oxide, copper chromite, lead/copper oxides, and lead salts in combination with carbon black as a catalyst on the burning rate and pressure exponent of these high‐energy propellants. A 7–9 % increase in the burning rates and almost no effect in pressure exponent values of propellant compositions without nitramine were observed. However, in case of nitramine‐based propellants as compared to propellant compositions without nitramines, slight increases of the burning rates were observed. By incorporation of ballistic modifiers, the pressure exponents can be lowered. The changes in the calorimetric values of the formulations by addition of the catalysts were also studied.     

Burning Characteristics of Ammonium Nitrate‐Based Composite Propellants Supplemented with Fe2O3

Ammonium nitrate (AN)‐based composite propellants have attracted a considerable amount of attention because of the clean burning nature of AN as an oxidizer. However, such propellants have several disadvantages such as poor ignition and a low burning rate. In this study, the burning characteristics of AN‐based propellants supplemented with Fe₂O₃ as a burning catalyst were investigated. The addition of Fe₂O₃ is known to improve the ignitability at low pressure. Fe₂O₃ addition also increases the burning rate, while the pressure exponent generally decreases. The increasing ratio (R) of the burning rate of the AN/Fe₂O₃ propellant to that of the corresponding AN propellant vs. the amount of Fe₂O₃ added (ξ) depends on the burning pressure and AN content. R decreases at threshold value of ξ. The most effective value of ξ for increasing the burning rate was found to be 4 % for the propellant at 80 % AN, and the value generally decreased with decreasing AN content. According to thermal decomposition kinetics, Fe₂O₃ accelerates the reactions of AN and binder decomposition gases in the condensed‐ and/or gas‐phase reaction zones. The burning characteristics of the AN‐based propellant were improved by combining catalysts with differing catalytic mechanisms instead of supplementing the propellant with a single catalyst owing to the multiplicative effect of the former.     

Burning Rate – Pressure Relationship of NG‐PE‐PCP‐based High Energy Propellants

Nitramines are known to produce lower burning rates and higher pressure exponent (η) values. Studies on the burning rate and combustion behavior of advanced high‐energy NG/PE‐PCP/HMX/AP/Al based solid propellant processed by slurry cast route were carried out using varying percentages of HMX and AP. It was observed that propellant compositions containing only AP and Al loaded (total solids 75 %) in NG plasticized PE‐PCP binder produce comparatively lower pressure exponent (η) values similar to AP‐Al filled HTPB based composite propellants. However, energetic propellants containing high level of nitramine (40–60 %) produce high pressure exponent (0.8–0.9) values in the same pressure range. Incorporation of fine particle size AP (ca. 6 μm) and change in its concentration in the propellant composition reduces η value marginally and influences the burning rate. However, such compositions have higher friction sensitivity.     

Combustion Characteristics of a Novel Grain‐Binding High Burning Rate Propellant

The novel grain‐binding high burning rate propellant (NGHP) is prepared via a solventless extrusion process of binder and spherical propellant grains. Compared with the traditional grain‐binding porous propellants, NGHP is compact and has no interior micropores. During the combustion of NGHP, there appear honeycomb‐like burning layers, which increase the burning surface and the burning rate of the propellant. The combustion of NGHP is a limited convective combustion process and apt to achieve stable state. The larger the difference between the burning rate of the binder and that of the spherical granular propellants exists, the higher burning rate NGHP has. The smaller the mass ratio of the binder to the spherical granular propellants is, the higher the burning rate of NGHP is. It shows that the addition of 3 wt.‐% composite catalyst (the mixture of lead/copper complex and copper/chrome oxides at a mass ratio of 1 : 1) into NGHP can enhance the burning rate from 48.78 mm⋅s⁻¹ in the absence of catalyst to 56.66 mm⋅s⁻¹ at P=9.81 MPa and decrease the pressure exponent from 0.686 to 0.576 in the pressure range from 9.81 to 19.62 MPa.     

Burning Rates and Thermal Behavior of Bistetrazole Containing Gun Propellants

The influence of two selected bistetrazoles, 5,5′‐bis(1H‐tetrazolyl)‐amine (BTA) and 5,5′‐hydrazinebistetrazole (HBT), on the combustion behavior of a typical triple‐base propellant was investigated. Seven propellant formulations, one reference and six others incorporating 5 %, 15 %, and 25 % of either HBT or BTA compounds, respectively, were mixed and extruded into a cylindrical, no perforations, geometry. The resulting propellants showed high burning rates, up to 93 % higher than the reference formulation at 100 MPa. However, the increase in burning rates came at the cost of higher burning rate dependency on pressure, with a pressure exponent as high as 1.4 for certain formulations. HBT‐containing propellants showed notably lower flame temperature when compared to the reference formulation, with a flame temperature reduction of up to 461 K for the propellant containing 25 % HBT. The thermal behavior of the propellants was also investigated through DSC experiments. The addition of bistetrazoles provided lower decomposition temperatures than the pure nitrogen‐rich materials, indicating that the two compounds probably react readily with the −ONO₂ groups present in the nitrocellulose and the plasticizers used in the formulation. The onset temperature of all propellants remained within acceptable ranges despite the observed decrease caused by the addition of the bistetrazole compounds.