碳物质在固体推进剂中的功能及其作用机理

综述了碳黑（CB）、富勒烯烟炱（FS）、C60（Buckmister Fuller）、碳纤维（CF）及碳纳米管（CNTs）在固体推进剂催化燃烧中的作用、作用规律及作用机理。在双基系推进剂中加入碳黑和C60可富集催化剂,阻滞催化剂凝聚,使双基推进剂产生平台或麦撒效应,推进剂压力指数降低,低压下的燃速大幅度提高。碳纤维改善了推进剂燃烧表面的导热,增加了推进剂基体强度,可提高其燃速,预防复合推进剂的破裂。推进剂中的碳纤维、碳纳米管能加速含能材料的分解,提高推进剂的燃速。展望了固体推进剂中碳物质的发展方向。     

含N,N-二硝基哌嗪无烟改性双基推进剂的燃烧性能

以CMDB推进剂为基础,用N,N-二硝基哌嗪(DNP)替代推进剂中的RDX,研究了DNP含量、燃烧稳定剂(CaCO3、TiO2、MgO及Al2O3)、燃烧催化剂(铅盐、铅盐/铜盐、铅盐/铜盐/炭黑)对DNP-CMDB推进剂燃烧性能的影响。结果表明,DNP可明显降低无烟CMDB推进剂的燃速,当DNP完全替代RDX时,在18MPa压强下推进剂的燃速降低约68%;铅盐/铜盐/炭黑燃烧催化剂复配体系能够有效降低DNP-CMDB推进剂的燃速压强指数,使其出现平台燃烧效应。     

RDX-CMDB推进剂燃速温度敏感系数的实验研究

为了揭示RDX-CMDB推进剂中各常见组分对其燃速温度敏感系数的影响规律,制备了一系列含RDX、铝粉及燃烧催化剂的CMDB推进剂样品。采用氮气靶线法测得其在2~14MPa下的燃速温度敏感系数(σp)。讨论了RDX含量、铝粉、燃烧催化剂对RDX-CMDB推进剂燃速温度敏感系数的影响。结果表明,提高工作压强、增加RDX含量、添加燃烧催化剂均有助于降低RDX-CMDB推进剂在一定初始条件下的燃速温度敏感系数。配方中引入铝粉后可降低中低压下RDX-CMDB推进剂的燃速温度敏感系数,且燃速温度敏感系数几乎不随压强变化而变化。选用含邻苯二甲酸铅和没食子酸铋锆作燃烧催化剂,均可在2~10MPa下降低RDX-CMDB推进剂的燃速压强指数,同时降低燃速温度敏感系数。     

含相稳定硝酸铵CMDB推进剂的机械感度和燃烧性能

通过测试撞击感度、摩擦感度和燃速,研究了含相稳定硝酸铵(PSAN)的改性双基(CMDB)推进剂的燃烧性能和机械感度。结果表明,PSAN可改善CMDB推进剂的机械感度;用PSAN作氧化剂,其推进剂的燃速低于RDX作氧化剂的燃速,压强指数高于后者的压强指数;1～5MPa压力范围内随PSAN在配方中含量的增加,推进剂的燃速降低,压强指数升高。     

含黑索今酮的火药热分解及燃烧性能研究

用ＤＳＣ技术考察了７种含黑索今酮（Ｋｅｔｏ－ＲＤＸ）火药的热分解特性,并对其中３种进行了密闭爆发器测试。将ＤＳＣ数据对动力学方程进行拟合以求得动力学参数。从密闭爆发器测试结果转换得到了该３种火药的燃速－压力曲线,并对其进行了转折性分析。结果表明,向火药中加入Ｋｅｔｏ－ＲＤＸ可提高火药燃速并降低其热分解表观活化能。含Ｋｅｔｏ－ＲＤＸ的火药其燃速压力指数在低压区较在高压区为高。在火药中同时存在有Ｋｅｔｏ－ＲＤＸ和ＲＤＸ对火药热分解和燃烧的稳定性是不利的。仅由Ｋｅｔｏ－ＲＤＸ与双基粘结剂组成的火药,其燃速压力指数较由ＲＤＸ与双基粘结剂组成的火药为低。     

Effects of an Organic‐inorganic Nanocomposite Additive on the Combustion and Erosion Performance of High Energy Propellants Containing RDX

A nanocomposite microsphere consisting of solid paraffin, nano‐TiO₂, nano‐BN, zeolitic imidazolate framework‐67 particles and polymethyl methacrylate was prepared and applied as a functional additive for high energy propellants (with about 23 wt % RDX) to reduce the barrel erosion and improve its combustion performance as well. High energy propellants modified with the nanocomposite were manufactured by a solvent extrusion technique. According to the scanning electron microscope and differential scanning calorimetry results, there exists a good compatibility between the nanocomposite and propellant matrix. The energy and combustion performance as well as erosion of the modified propellants were studied by a closed bomb test and an erosion tube device, respectively. Results showed that compared with the unmodified propellant, both the erosion and energy performance of modified high energy propellant gradually decreased with the increase of nanocomposites contents. When the content of nanocomposites was 5.1 %, the erosion mass of the modified propellant reduced to 37.0 % while the propellant force only decreased 5.7 %, indicating that the nanocomposite has enormous ability to improve gun erosion resistance while barely affect energy performance of propellant. Furthermore, the closed bomb burning curves of the samples showed that addition of nanocomposites to propellant matrix could prolong the combustion time, efficiently inhibit the initial generation rate of combustion gas, and further achieve the progressive burning of the propellants.     

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.     

Temperature profile in the combustion wave of low calorific value propellants

Combustion wave temperature profiles are determined for two low calorific value propellants (Q _c = 2189 and 2518 kJ/kg). It is shown that the structure and parameters of the combustion wave differ significantly from those for previously studied propellants of medium (propellant N) and high (propellant NB) calorific values. At a relatively short distance from the burning surface, the temperature is significantly (180–270 K) higher than the calculated value due to fact the combustion products contain carbon black from the decomposition of heat-resistant dibutyl dinitrotoluene and dibutyl phthalate. Then, part of carbon black reacts endothermically with CO₂ and H₂O, leading to a decrease in temperature, which for the first sample is nevertheless 100–140 K higher than the thermodynamic value. For the investigated propellants, the activation energy of the leading reaction is the same as for the previously studied propellants, suggesting a common decomposition kinetics of the condensed phase regardless of the propellant composition. However, a uniform dependence of the burning rate on surface temperature is not observed. For low calorific value propellants, the surface temperatures are close to those for propellant N although their burning rate is significantly (2–2.2 times) lower. The causes of this fact are considered.     

有机铋铜复盐对DNTF/HMX-CMDB推进剂燃烧性能的影响

研究了有机铋铜复盐(Gal-BiCu)与炭黑、不同芳香族铜盐(Cu1和Cu2)及金属燃烧功能助剂(NB)复配对DNTF/HMX-CMDB推进剂燃烧性能的影响。分析了Gal-BiCu与其他催化剂复配后影响DNTF/HMX-CMDB推进剂燃烧行为的原因。结果表明,Gal-BiCu能有效调节DNTF/HMX-CMDB推进剂的燃烧性能,提高推进剂燃速,显著降低压强指数;当Gal-BiCu与炭黑、Cu1、NB复合时,催化性能更佳;NB质量分数为0.5%时,推进剂在8~20MPa较宽区间内出现平台燃烧,压强指数n≤0.2;8~15MPa区间内压强指数降至0.11。     

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.     

1,3,3-三硝基氮杂环丁烷作为增塑剂的无烟CMDB推进剂综合性能研究

对1,3,3-三硝基氮杂环丁烷（TNAZ）作为增塑剂的无烟CMDB推进剂的能量性能、安全性能、燃烧性能和热行为进行了研究,结果表明,TNAZ部分代替NG和DINA应用到无烟CMDB推进剂中,一定程度上提高了推进剂的能量,对推进剂的热稳定性影响不大,推进剂的机械感度和不同压力下推进剂的燃速均有所降低。微量量热实验研究发现,高压下TNAZ作为增塑剂的无烟CMDB推进剂的分解温度为180-235℃,其中TNAZ的分解温度大于220℃,而常压下该推进剂中的TNAZ在70～180℃时即挥发或升华。TNAZ的含量变化对TNAZ—CMDB推进剂火焰结构的影响不明显。     

Preparation and Properties of a nRDX‐based Propellant

The incorporation of nano‐scaled cyclotrimethylene trinitramine (nRDX) in nitrocellulose (NC)‐based propellants poses processing problems when following conventional methods. Hence, a new preparation method containing a pre‐dispersion process was developed, by which 30 mass % RDX (290 nm) was incorporated in the propellant. Meanwhile, the corresponding 290 nm, 12.85 μm and 97.76 μm RDX‐based propellants were prepared for comparison using a conventional method. The morphology, structure, ballistic and mechanical properties of the prepared propellants were characterized by scanning electron microscopy (SEM), density analyzer, closed vessel (CV), uniaxial tensile tester and impact tester. The results indicate that the nRDX particles were uniformly dispersed in the NC/NG/TEGDN matrix using the novel method, while agglomerated and recrystallized into large particles with the conventional method. The propellant density increased with decreasing RDX particle size. In particular, the 290 nm RDX‐based propellant exhibited a higher burning rate and lower average pressure exponent (α =0.958) compared to the 12.85 μm RDX‐based propellant (α =1.043). The tensile strength, elongation at break and impact strength of the RDX‐based propellant at −40 °C, 20 °C and 50 °C were dramatically improved by using 290 nm RDX with the novel method.     

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.     

AP-CMDB 推进剂稳态燃烧性能计算研究

建立了一个ＡＰ－ＣＭＤＢ推进剂稳态燃烧模型。该模型可用于ＡＰ－ＣＭＤＢ推进剂和经典双基推进剂燃速特性的模拟计算，其计算结果与文献值相符合，说明该模型是合理、可行的。ＡＰ－ＣＭＤＢ推进剂计算结果表明，ＡＰ粒径减小，ＡＰ含量增加，推进剂燃速升高；而含能粘结剂——ＤＢ母体的含能程度越高，即ＮＧ含量增加，或ＮＣ的硝化度加大，都有利于提高推进剂的燃速。     

Effect of RDX and HMX on the Efficiency of Catalysts for Double–Base Propellant Combustion

High explosives (RDX or HMX) are added to double–base propellant formulations to improve their energy characteristics. The influence of these HE on the catalysis of propellant combustion practically has not been discussed in the literature. The present paper considers the role of RDX and HMX in the catalysis of double–base propellant combustion. Propellants having various compositions and energy characteristics were studied experimentally. It is established that RDX and HMX decrease the burning rate of double–base propellants (without catalysts) with moderate and high calorific values irrespective of their effect on the energy and combustion characteristic of the propellants. It is shown that if the burning rate of a propellant is affected by catalysts, the addition of RDX or HMX to this propellant (in excess of 100%) does not decrease the relative efficiency of catalysis but even increases it somewhat.     

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.     

双基系推进剂用生态安全的含铋催化剂

综述了生态安全的含铋催化剂对双基和ＲＤＸ－ＣＭＤＢ推进剂燃烧性能的影响,分析比较了铋化物和铅化物的催化作用。分析结果表明,粒度小、分散性好的铋化物能够取代生态安全性差的含铅燃速催化剂用于双基系推进剂中。     

Burning Characteristics and Thermochemical Behavior of AP/HTPB Composite Propellant Using Coarse and Fine AP Particles

The burning rate of AP/HTPB composite propellant increases with increasing AP content and with decreasing AP size. In addition, the burning rate can be enhanced with the addition of Fe₂O₃. The burning characteristics and thermal decomposition behavior of AP/HTPB composite propellant using coarse and fine AP particles with and without Fe₂O₃ at various AP contents were investigated to obtain an exhaustive set of data. As the AP content decreased, the burning rate decreased and the propellants containing less than a certain AP content self‐quenched or did not ignite. The self‐quenched combustion began at both lower and higher pressures. The lower limit of AP content to burn the propellant with coarse AP was lower than that with fine AP. The lower limit of AP content to burn was decreased by the addition of Fe₂O₃. The thermal decomposition behavior of propellants prepared with 20–80 % AP was investigated. The decrease in the peak temperature of the exothermic decomposition suggested an increased burning rate. However, a quantitative relationship between the thermochemical behavior and the burning characteristics, such as the burning rate and the lower limit of AP content to burn, could not be determined.     

Ballistic Modification of RDX-Based CMDB Propellants

The effect of lead and copper salts and certain metallic oxides was studied on the burning rates of RDX-based CMDB propellants in the pressure region 35–105 [kg/cm²]. Lead methylene disalicylate (LMDS), basic copper salicylate (BCS). cobaltic oxide and lead stannate produced higher burning rates by 10%–16%. However, these additives were comparatively more effective with nitramine-based CMDB propellants than AP-based CMDB propellants. Fluorides of iron, lead and chromium were ineffective as burning rate catalysts. Inclusion of carbon black along with lead salts or metallic oxide gave only marginally higher burning rates. None of the ballistic modifiers studied produced plateau/mesa effect.     

Influence of Particle Size on the Combustion of CL‐20/HTPB Propellants

The effect of nitramine particle size on the combustion behavior of inert binder based propellants has been extensively studied for RDX and HMX, but not CL‐20. Although materials such as RDX and HMX are useful for particular combustion applications, CL‐20 has a greater potential to improve the oxygen balance and energy density of a propellant. The current work investigates the effect of CL‐20 particle size on the combustion of CL‐20/HTPB propellants down to submicrometer sizes. An influence of particle size on the burning rate and combustion mechanism is reported. The 30 micrometer formulation burning rate data showed evidence of convective burning specifically at higher pressures, but the pressure dependence was comparable to neat CL‐20 at pressures below 8 MPa. A change in the combustion mechanism of the submicrometer formulation as a function of pressure was determined to be a result of the interaction of the propellant flame and the combustion residue. Data suggested that at low pressures diffusion in terms of active cooling was dominant for the submicrometer formulation. Higher pressure data for both the submicrometer and 3 micrometer formulations suggest the degree of active cooling is decreased as the burning rate pressure exponent is near 0.5 for both propellants. The indirect evidence for the presence of a melt layer for CL‐20 propellants is discussed.