几种典型固体推进剂的燃烧转爆轰实验研究

为探索影响固体推进剂发生燃烧转爆轰的因素,对4种典型固体推进剂样品进行了实验研究。通过选用不同壁厚的样品管及改变样品的装填形式,实现了燃烧转爆轰。利用电离探针对试样稳定爆轰时的爆速进行了测试。结果表明,含RDX、NG高敏感度含能材料的颗粒状CMDB推进剂及药柱内部含有大量气孔的NEPE推进剂发生燃烧转爆轰。推进剂的配方、装药形式、外界约束条件是影响推进剂发生燃烧转爆轰的主要因素。证明了推进剂在特定条件下可以发生燃烧转爆轰。     

含微米级AP的HTPB推进剂工艺性能和力学性能

制备了含微米级AP(质量分数大于50%)的HTPB推进剂药浆和标准试件,利用流变仪测试了+20℃和-40℃时药浆的表现黏度,用材料试验机测试了标准试件的力学性能,讨论了增塑比、AP粒度级配、键合剂等对HTPB推进剂工艺性能和力学性能的影响。结果表明,当增塑比为0.42、AP粒度级配采用25%的120μm AP、30%的6~8μm AP和20%的1μm AP时,推进剂样品6h的表观黏度为1 267Pa·s,低温延伸率达到38%。     

PVB基高固体含量推进剂胶片的力学性能

采用光辊压延工艺制备了含质量分数78%碳酸钙(CaCO3)的聚乙烯醇缩丁醛(PVB)基推进剂胶片。通过静态力学试验分析了不同相对分子质量PVB和11种液体石蜡对推进剂胶片力学性能的影响,用扫描电镜观察了推进剂胶片的剖片形貌。结果表明,以相对分子质量为40 000的PVB作黏合剂、醇质量分数为5%的液体石蜡作工艺助剂时,推进剂胶片内部结构致密,力学性能最佳,低温延伸率为2.97%,高温拉伸强度为3.55MPa。用黑索今(RDX)全部替代CaCO3时,可安全稳定地制备PVB基高固体含量推进剂。含43.25μm RDX的推进剂比含21.02μm RDX的推进剂的拉伸强度及延伸率分别高45%和17%。     

CL-20含量及其粒度级配对NEPE推进剂燃烧性能的影响

采用静态与水下声发射法测试了CL-20含量及其粒度级配对NEPE推进剂燃速与压强指数的影响;采用DSC与TG-IR联用研究了CL-20对NEPE推进剂热分解行为的影响。结果表明,随着CL-20质量分数由42%增至50%,推进剂燃速与压强指数上升,燃烧效率提高,表明CL-20氧化能力高于GAP/硝酸酯含能黏合剂体系;随着CL-20/HMX、CL-20/Al质量比增高,推进剂燃速上升,燃烧效率上升;CL-20对推进剂燃速和压强指数的贡献高于HMX;随着CL-20/AP质量比增高,CL-20/AP混合体系分解产物氧化能力降低,燃烧反应速率降低,燃速降低;CL-20粒度级配对NEPE推进剂燃烧行为影响显著,当CL-20的粒径(d50)在5~50μm时,随着细粒度CL-20含量增高,推进剂燃速与燃速压强指数下降;当体系中存在超细粒度CL-20(d50=500nm)时,推进剂燃速与燃速压强指数随着超细粒度CL-20含量的增加而有所增加,4种粒度CL-20对NEPE推进剂燃速的贡献顺序为:粗粒度>中粒度>超细粒度>细粒度。     

含1,1–二氨基–2,2–二硝基乙烯推进剂的能量特性参数计算研究

利用国军标方法及CAD系统软件,在标准条件(pc∶p0=70∶1)下,计算了含1,1-二氨基-2,2-二硝基乙烯(FOX-7)的各类推进剂的能量特性参数,分析了氧化剂(AP、RDX、CL-20)及黏合剂(HTPB、PET、GAP、PBAMO)等成分对FOX-7推进剂能量特性的影响。结果表明,将AP加入HTPB/FOX-7推进剂配方中取代FOX-7可有效改善氧条件,有利于推进剂能量的提高。在黏合剂含量较低(质量分数<8%)的推进剂体系中,使用惰性黏合剂有利于提高推进剂的能量;而在黏合剂含量较高(质量分数>10%)的推进剂体系中,使用含能黏合剂提高推进剂能量的幅度优于惰性黏合剂,且GAP优于PBAMO。用FOX-7取代NEPE推进剂中的AP,推进剂最大理论比冲可达2 567 N.s/kg。由GAP/FOX-7/RDX组成的无烟推进剂,在很宽的范围内都可以达到2 400 N.s/kg以上的理论比冲值。     

含RDX低燃速丁羟推进剂的配方研究

为满足某发动机装药需求,设计了固体质量分数为87.5%含RDX的低燃速丁羟推进剂配方,采用最小自由能法进行理论计算,研究了RDX和改性草酸铵对热力学参数的影响.用BSFΦ165标准试验发动机测试了比冲和燃速.结果表明,含RDX低燃速推进剂配方中,RDX和改性草酸铵的含量影响其热力学参数.当RDX质量分数为(10.0%),改性草酸铵为2.0%时,低燃速推进剂的实测比冲为2 374 N·s·kg~(-1),比冲效率为0.919,燃速为4.12 mm·s~(-1);通过添加少量改性草酸铵、改变氧化剂的粒度级配,能够在保证推进剂能量基本不变的前提下,满足含RDX低燃速丁羟推进剂配方的低燃速指标要求.     

撞击作用下螺压复合改性双基推进剂药片的响应

采用落锤仪研究了螺压复合改性双基(CMDB)推进剂药片在撞击作用下发生分解、燃烧或爆炸响应的临界值,获得了不同RDX含量、样品厚度及样品温度对推进剂在撞击作用下响应临界值的影响规律。结果表明,在推进剂中引入RDX不会增加推进剂对撞击刺激的敏感程度;RDX的质量分数为0~54.5%时,随着RDX含量的增加,推进剂药片对撞击刺激的敏感程度逐渐降低;样品厚度为1、2、3mm时,随着样品厚度的增加,推进剂药片对撞击刺激的敏感程度显著降低;推进剂在70℃时对撞击刺激比25℃时更加敏感。     

过渡金属催化剂对低燃温双基推进剂性能的影响

为探索过渡金属催化剂粒度对低燃温双基推进剂燃烧性能、点火性能的影响,分别测试了含不同粒度(1μm、3μm、5μm)过渡金属催化剂及粒度级配的低燃温双基推进剂的燃速。以压强指数较小作为优选标准,对优选配方进行放大试验。采用螺旋压伸成型工艺制备了Φ50mm标准发动机药柱并进行发动机点火试验。结果表明,过渡金属催化剂可显著改善推进剂在低压下的燃烧性能,降低压强指数及临界燃烧压强,使推进剂在2MPa下能稳定燃烧。该装药在低温下(-40℃)点火正常、燃烧稳定。     

低铝粉含量的HMX/HTPB推进剂研究

对低铝粉含量的HMX/HTPB推进剂进行了配方研究。为获得少烟、高密度、高模量、高燃速、低压强指数的优良的综合性能,配方调试以铝粉质量分数<10%,用HMX替代部分AP来达到少烟目的;以HTPB/TDI/MAPO/STR黏合剂体系来获取高模量;通过AP级配调节,燃速催化剂的选择等方法,使推进剂具有不挥发物质量分数≥88.5%、20℃下密度≥1.78 g/cm3、σm≥3.1 MPa,燃速≥40 mm/s的良好性能,并具有药浆初始黏度低,流动、流平性好的优点。HTPB/AP/Al/HMX四组元推进剂经BSFΦ127标准发动机地面试车,内弹道p–t曲线在压强30 MPa以下,燃烧稳定;推进剂燃烧未急升导致压强异常现象。研制成的药柱经发动机地面试验可知混合比冲高达2 456.7 N·s/kg。     

Al粉在高燃速AP/CMDB推进剂中的应用

采用量热仪、燃速仪、PDSC分别研究了含不同粒度和含量Al粉的高燃速AP/CMDB推进剂的爆热、燃烧性能与热分解特性。结果表明,推进剂爆热与Al粉的含量成正比;Al粉质量分数为0~8%时,对推进剂燃烧性能无明显影响;Al粉粒度由14μm减小至5μm时,推进剂爆热降低40J/g,热分解放热量增加107J/g,7~10MPa压强下推进剂燃速提高1~1.8mm/s,7~22MPa下压强指数由0.56降至0.50;当Al粉(质量分数3%)粒度减小为150nm时,推进剂的爆热降低93J/g,热分解放热量增加343J/g,18~22MPa压强下的燃速提高2~3mm/s。     

含3,5-二硝氨基-1,2,4-三唑肼盐推进剂的能量特性计算

为评价新型高氮化合物3,5-二硝氨基-1,2,4-三唑肼盐(HDNAT)作为固体推进剂组分的应用潜力,采用NASA-CEA软件,在标准条件下(pc∶p0=70∶1),计算了含HDNAT的丁羟推进剂(HTPB)、聚叠氮缩水甘油醚(GAP)推进剂和改性双基推进剂(CMDB)的能量特性。绘制了HTPB/Al/AP/HDNAT推进剂(金属Al的最大质量分数为20%)的标准理论比冲Isp、特征速度C*、燃烧温度Tc、燃气平均相对分子质量Mw的等性能三角图。结果表明,HDNAT单元推进剂的比冲为2 533.0N·s/kg;在HTPB推进剂中,当HDNAT质量分数为50%时,Isp最大为2 658.0N·s/kg,较基础配方提高了326.6N·s/kg;在GAP推进剂中,当HDNAT质量分数为30%时,Isp最大为2 529.0N·s/kg,较基础配方提高了252.7N·s/kg;在CMDB推进剂中,当HDNAT质量分数为27%时,Isp最大为2 593.1N·s/kg,较基础配方提高了57.3N·s/kg。     

Application of the BAMO‐AMMO Alternative Block Energetic Thermoplastic Elastomer in Composite Propellant

A BAMO‐AMMO alternative block (BAAB)‐based thermoplastic composite propellant with 80 % solid content was prepared using BAAB energetic thermoplastic elastomer (ETPE) as the binder, and the formulation was optimized through energy calculation. The densities, heats of explosion, glass‐transition temperatures, and mechanical properties of the samples were determined by surface tension measurements, oxygen bomb calorimetry, differential scanning calorimetry and static tensile tests, respectively. The results showed that this composite propellant can reach a standard theoretical specific impulse of 275.45 s (10 MPa), a density of 1.8102 g cm⁻³, a heat of explosion of 6256 kJ kg⁻¹, a T_g of −50.46 °C, a tensile strength of 1.56 MPa and an elongation at break of 20 %, thus presenting a superior comprehensive property to BAMO‐AMMO random block (BARB)‐based thermoplastic composite propellant.     

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.     

Applying modified hyperbranched polyester in hydroxyl‐terminated polyether/ammonium perchlorate/aluminium/cyclotrimethylenetrinitramine (HTPE/AP/Al/RDX) composite solid propellant

Composite solid propellants demand fine and stable mechanical properties, creep resistance and stress relaxation performance during their long storage and usage time. In this study, modified hyperbranched polyester (MHBPE) was prepared and introduced into HTPE/AP/Al/RDX (HTPE, hydroxyl‐terminated polyether; AP, ammonium perchlorate; RDX, cyclotrimethylenetrinitramine) solid propellant as an effective additive. The static tensile and dynamic mechanical properties of this propellant before and after the introduction of MHBPE were evaluated. The elevated interfacial interaction by using MHBPE between the binder and RDX fillers improved the toughness and elasticity of the propellant. The enhancement mechanisms were also confirmed by the influence on the fracture surface morphology of the binder which was investigated by SEM. In addition, some influence on the dynamic mechanical properties of HTPE/AP/Al/RDX propellant caused by MHBPE was investigated by dynamic mechanical analysis. The creep behaviors of the HTPE/AP/Al/RDX propellants with and without MHBPE were also investigated at different stresses and temperatures. Reduced creep strain rate and strain were obtained for the modified propellant, implying enhanced creep resistance performance. The creep properties were quantitatively evaluated using a six‐element model and the long‐term creep performance of the propellant was predicted using the time–temperature superposition principle. A creep behavior of nearly 10⁶ s at 30 °C could be acquired in a short‐term experiment (800 s) at 30–70 °C. Moreover, the stress relaxation investigation of the propellants with and without MHBPE at ?40 °C, 20 °C and 70 °C suggested that MHBPE/HTPE/AP/Al/RDX propellant possessed better response ability to deformation. Thus, the application of MHBPE provides an efficient route of reinforcement to enhance the creep resistance and stress relaxation properties. © 2020 Society of Chemical Industry     

B/Fe_2O_3/NC复合物的制备及其对HTPB/AP推进剂性能的影响

为改善硼粉(B)的性能和纳米氧化铁(Fe_2O_3)在固体推进剂中的分散性,用静电喷雾法制备了B/Fe_2O_3/NC复合物,采用扫描电镜(SEM)表征了复合物的表面形貌,用TG-DSC分析了复合物的热性能及其对HTPB/AP推进剂热性能的影响,并用燃速测试和密闭爆发器实验研究了该复合物对HTPB/AP推进剂燃烧性能的影响。结果表明,所制备的B/Fe_2O_3/NC复合物均以团聚体的形式存在,复合物中B的活性提高,其氧化反应温度提前;团聚硼粉对HTPB/AP推进剂燃烧性能的改善效果明显优于原料硼粉;加入Fe_2O_3后,会进一步改善含硼推进剂的燃烧性能,而且随Fe_2O_3含量的增加,在密闭爆发器中HTPB/AP推进剂达到最高压力所需的时间逐渐减小。当Fe_2O_3的质量分数为8%时,推进剂在常压空气中的燃速最大,为不添加B/Fe_2O_3/NC复合物的HTPB/AP推进剂的2.77倍。B/Fe_2O_3/NC复合物对推进剂的热分解具有一定催化作用,且随Fe_2O_3含量的增加催化作用增强。     

Rheological studies on energetic thermoplastic elastomers

Energetic thermoplastic elastomers containing energetic groups, such as azido, nitrato, nitro, and so forth, are emerging as attractive binder systems for advanced solid rocket propellants. Poly[3,3‐bis(Azidomethyl) oxetane (BAMO)‐co‐3‐azidomethyl‐3‐methyl oxetane (AMMO)] comprising hard crystalline BAMO segment and the soft/amorphous AMMO segment in various molar ratios (80 : 20, 50 : 50 and 20 : 80) were synthesized during the present work. The homo polymers namely Poly‐BAMO and Poly‐AMMO were also synthesized. All the polymers and copolymers were characterized by spectral and thermal methods. They were found to be thermally stable. The most promising 80 : 20 copolymer softened at 56°C with T_g of −36°C. Rheological studies were also carried out to determine their suitability as a binder in explosive and propellant formulations. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010