摘要
以零氧平衡为配比依据,硝化棉(NC)为粘结剂、高氯酸铵(AP)为氧化剂、环三亚甲基三硝胺(RDX)和纳米铝粉(Al)为燃烧剂,分别采用机械混合法和静电喷雾法制备RDX/NC/AP/Al复合炸药。采用扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT‑IR)和热重‑差示扫描量热仪(TG‑DSC)对样品的形貌、结构和热性能进行表征;并利用高速摄影仪、撞击感度仪和摩擦感度仪和对样品的燃烧过程和机械感度进行了分析。结果表明:机械混合法制得的RDX/NC/AP/Al复合炸药颗粒为球形;采用静电喷雾法制得的RDX/NC/AP/Al复合炸药颗粒为团聚微球;机械混合法和静电喷雾法制得的RDX/NC/AP/Al复合炸药中的组分NC、RDX、AP、Al之间为物理复合;采用机械混合法和静电喷雾法制得的RDX/NC/AP/Al复合炸药的失重过程分为两个阶段(200~210 ℃和250~350 ℃),第一阶段是部分RDX和AP的分解,第二阶段是剩余RDX和NC的分解;与机械混合法制得的RDX/NC/AP/Al复合炸药相比,静电喷雾法制得的RDX/NC/AP/Al复合炸药的表观活化能提高了41.25 kJ·mo
图文摘要
环三次甲基三硝胺(RDX,C3H6N6O6)是当今应用最为广泛的硝胺炸药,其爆炸威力极强,是TNT的1.5倍,但由于其机械感度高、体积燃烧焓和能量密度均较低,使得RDX无法满足各方面的性能需
静电喷雾技
氧平衡是决定炸药各组分之间的重要依据之
NC,含氮量12.76%,255厂;RDX,工业级,粒径10~110 µm,805厂;纳米Al,平均粒径为96.5 nm,上海超威纳米科技有限公司;丙酮,N,N‑二甲基酰胺(DMF),分析纯,天津天大化学仪器厂。
SS系列静电喷雾装置,北京永康乐业科技发展有限公司。
按照氧平衡为零的原则,将一定质量的NC(0.04 g)、RDX(1 g)、AP(0.588 g)和纳米Al粉(0.412 g)溶解在丙酮和DMF混合溶液中(体积比为1∶1,5 mL),然后在磁力搅拌器上进行蒸发结晶(温度55 ℃),蒸发40 min后,过滤、冷冻干燥得到复合炸药。制备流程见

图1 机械混合法制备RDX/NC/AP/Al复合物流程图
Fig.1 Flow chart of RDX/NC/AP/Al composive explosives prepared by mechanical mixing mthod
按照氧平衡为零的原则,将一定质量的NC(0.04 g)、RDX(1 g)、AP(0.588 g)溶解在DMF(5 mL)中形成混合溶液,再将纳米Al粉(0.412 g)加入混合溶液中,超声分散形成稳定的悬浮液,然后进行静电喷雾操作,具体见

图2 静电喷雾法制备RDX/NC/AP/Al复合物流程图
Fig.2 Flow chart of RDX/NC/AP/Al composive explosives prepared by electrostatic spray method
扫描电镜(SEM)表征:采用SU8020型扫描电子显微镜(日本日立公司)观察样品的粒径、表面形貌,样品测试前进行喷金处理,扫描电子显微镜工作电压为5 kV。
组分分析:采用Tensor‑27型傅里叶变换红外光谱仪(布鲁克光学仪器有限公司)(FT‑IR)对样品的组分进行分析,测试波段范围为400~4000 c
热性能表征:采用STA 449 F5 Jupiter 型TG‑DSC热分析仪(德国耐驰)对样品的热性能进行分析,升温速率为5,10,20 K·mi
燃烧测试:采用快速加热丝对样品进行点燃,采用PHANTOM v 12.0 UX50高速摄像机(美国视觉研究影像公司)记录燃烧过程。
撞击感度测试:参照国标GB/T2178‑2005,采用BFH‑12A型落锤撞击感度仪(捷克OZM探索公司)测试样品的特性落高,测试条件为:落锤质量2.5 Kg,药量(35±1) mg。测试25发。
摩擦感度测试:参照国标GB/T2178-2005,采用FSKM‑10型摩擦感度仪(捷克OZM探索公司)测定样品的爆炸百分数。测试条件为:摆角90°,表压3.92 MPa,药量(20±1) mg,测试25发。
为研究机械混合与静电喷雾复合过程中炸药微观结构的变化,对原料RDX、机械混合法和静电喷雾法制得的RDX/NC/AP/Al复合炸药进行了SEM测试,结果如

a. raw RDX

b. RDX/NC/AP/Al composite explosive
prepared by mechanical mixing method

c. RDX/NC/AP/Al composite explosive
prepared by electrostatic spray method
图3 不同样品的的SEM图
Fig.3 SEM images of the different samples
采用傅里叶红外光谱仪对原料RDX、NC、Al、AP、机械混合法和静电喷雾法制得的RDX/NC/AP/Al复合炸药进行测试,所得FT‑IR谱图如

图4 各组分与RDX/NC/AP/Al复合炸药的红外光谱图
Fig.4 Fourier transform infrared spectroscopy of RDX/NC/AP/Al composite explosive and each component (RDX, NC, AP and Al)
将
原料RDX、机械混合法和静电喷雾所制得的RDX/NC/AP/Al复合炸药的DSC曲线如

a. raw RDX

b. RDX/NC/AP/Al composite explosive
prepared by mechanical mixing method

c. RDX/NC/AP/Al composite explosive
prepared by electrostatic spray method
图5 三种样品在不同升温速率下的DSC曲线图
Fig.5 DSC curves of three samples at different heating rates.
根据
(1) |
以1/Tp为横坐标,以ln[βi/(Tpi
Note: Ea,Apparent activation energy, kJ·mo
由
原料RDX、机械混合法和静电喷雾所制得的RDX/NC/AP/Al复合炸药在升温速率为10 K·mi

图6 不同样品的TG‑DTG曲线图
Fig.6 TG‑DTG curves of different samples
根据自加速分解温度(TASDT
(2) |
式中,R=8.314 J·(mol·K
对原料RDX进行点火燃烧测试,利用钨丝引燃RDX,RDX并未燃烧,整个过程仅伴随着大量的白色烟雾生成,无火花和火焰的出现,这是由于纯的RDX着火点较高,在开放的室内环境中较难点燃,故无法用高速摄影捕捉到燃烧过程。
采用快速加热丝的点火方式,并用5000帧/s的高速摄像机记录机械混合法和静电喷雾法所制得的RDX/NC/AP/Al复合炸药的燃烧过程,结果如

a. RDX/NC/AP/Al prepared by mechanical mixing method

b. RDX/NC/AP/Al prepared by electrostatic spray method
图7 RDX/NC/AP/Al复合炸药的燃烧过程
Fig.7 Combustion process of RDX/NC/AP/Al composite explosive
由
原料RDX、机械混合法制得的RDX/NC/AP/Al和静电喷雾法制得的RDX/NC/AP/Al复合炸药的撞击感度和摩擦感度测试数据见
从
(1)机械混合法制得的RDX/NC/AP/Al复合炸药为球状,粒径在200~700 nm之间;静电喷雾技术制备出的RDX/NC/AP/Al复合炸药为微球结构,粒径在100~500 nm之间。两种方法所制得的混合物中的组分之间复合方式为物理复合。
(2)和原料RDX相比,机械混合法和静电喷雾法制得的RDX/NC/AP/Al复合炸药的活化能分别提高了222.87 kJ·mo
(3)原料RDX在室内无法正常燃烧,机械混合法制得的RDX/NC/AP/Al复合炸药点火延时间约为39.8 ms,整个燃烧持续时间约为960 ms,静电喷雾法制得的RDX/NC/AP/Al复合炸药的点火延迟时间为18.4 ms,样品燃速较快,燃烧时间约为219.8 ms,纳米Al与催化剂AP的燃烧使得各组分之间相互加热,因此静电喷雾法所制得的RDX/NC/AP/Al复合炸药具有较高的燃烧速率。
(4)原料RDX的撞击感度为2 J,摩擦感度为144 N;机械混合法制得的RDX/NC/AP/Al复合炸药的撞击感度和摩擦感度分别为35 J和200 N,静电喷雾法制得的RDX/NC/AP/Al复合炸药的撞击感度和摩擦感度分别为>45 J和>350 N,由此可见,机械混合法和静电喷雾法制得的RDX/NC/AP/Al复合炸药的撞击感度和摩擦感度相较于原料RDX均大幅度降低,降感效果显著。
参考文献
GNANAPRAKASH K, CHAKRAVARTHY S R,JAYARAMAN K, et al. Combustion behaviour of composite sandwich propellants containing RDX[J]. Proceedings of the Combustion Institute, 2021, 38(3): 4451-4459. [百度学术]
YU Cun‑juan,XU Ya‑bei,YU Shuo, et al. Study on the thermal stability of octogen and other energetic materials (RDX, TNT, NQ, PBT, TDI and HTPB)[J]. Chemistry Select, 2020, 5(46): 14811-14815. [百度学术]
LIU Xin, AO Wen, LIU Huan, et al. Aluminum agglomeration on burning surface of NEPE propellants at 3-5 MPa[J]. Propellants, Explosives, Pyrotechnics, 2017, 42(3): 259-267. [百度学术]
周小清, 单军辉, 陈东, 等. 花球状LLM‑105晶体的构筑及性能[J].含能材料,2021,29(12):1168-1175. [百度学术]
ZHOU Xiao‑qing, SHAN Jun‑hui, CHEN Dong, et al. Synthesis and characterization of llM‑105 crystal[J]. Chinese Journal of Energetic Materials(Hanneng Cailiao), 2021,29(12):1168-1175. [百度学术]
LI Yuan‑yuan,NI Bing,LI Kun,et al. Preparation of ultrafine CL‑20 by wet grinding method and the study on its properties[J]. Propellants, Explosives, Pyrotechnics,2020,45(11):1720-1728. [百度学术]
YANG Jihua, CAI Xingwang. Process research of solution enhanced dispersion by supercritical fluids to prepare energetic material nano‑capsules[J]. Propellants, Explosives, Pyrotechnics, 2021, 46(10): 1611-1623. [百度学术]
吴喜娜,咸漠,陈夫山,等.DNA自组装制备CuO/Al纳米复合含能材料[J]. 含能材料, 2018, 26(12): 1038-1043. [百度学术]
WU Xi‑na, XIAN Mo, CHEN Fu‑shan, et al. Preparation of CuO/Al nanocomposites by DNA self‑assembly[J]. Chinese Journal of Energetic Materials(Hanneng Cailiao), 2018, 26(12): 1038-1043. [百度学术]
ZUO Bei‑lin,ZHANG Jia‑ling,CHEN Shu‑wen, et al. Fabrication of Si@AP/NC metastable intermixed nanocomposites (MICs) by electrospray method and their thermal reactivity[J]. Advanced Composites and Hybrid Materials, 2019, 2(2): 361-372. [百度学术]
YAN S,JIAN G Q,ZACHARIAH M R.Electrospun nanofi‑ ber‑based thermite textiles and their reactive properties[J]. Applied Materials & Interfaces, 2012, 4: 6432-6435. [百度学术]
甘璐瑶, 李宁, 李亚宁, 等. 溶液参数对n‑Al/F2604复合粒子微观形貌的影响机制[J]. 含能材料, 2018, 26(10): 881-887. [百度学术]
GAN Lu‑yao, LI Ning, LI Ya‑ning, et al. Effect of Solution Parameters on the Microstructure of n‑Al/F2604 composite Particles[J]. Chinese Journal of Energetic Materials(Hanneng Cailiao), 2018, 26(10): 881-887. [百度学术]
胡绵伟,张哲,刘晓莲,等. 静电喷雾法制备HMX/F2603复合物及其性能研究[J]. 火炸药学报, 2020, 43(6): 608-613+619. [百度学术]
HU Mian‑wei, ZHANG Zhe, LIU Xiao‑lian, et al. Preparation of HMX/F2603 composite by electrostatic spray method and its properties [J]. Chinese Journal of Explosives & Propellants, 2020, 43(6): 608-613+619. [百度学术]
黄荣慧,闫石,王现锋,等. 静电喷雾法制备超细CL‑20基复合含能微球及其性能研究[J].火炸药学报, 2017, 40(6): 49-54. [百度学术]
HUANG Rong‑hui, YAN Shi,WANG Xian‑feng, et al. Preparation and properties of ultra‑fine CL‑20 matrix energetic microspheres by electrostatic spraying[J]. Chinese Journal of Explosives & Propellants, 2017, 40(6): 49-54. [百度学术]
LUO T T, WANG Y, HUANG H, et al. An electrospun preparation of the NC/GAP/Nano‑LLM‑105 nanofiber and its properties[J]. Nanomaterials, 2019, 9: 854-869. [百度学术]
梁宁, 陈丽红, 冀威, 等. 静电喷雾法制备RDX/NC/Al复合炸药[J]. 火炸药学报, 2020, 43(6): 620-625. [百度学术]
LIANG Ning, CHEN Li‑hong, JI Wei,et al.Preparation of RDX/NC/Al composite explosive by electrostatic spray method[J]. Chinese Journal of Explosives & Propellants, 2020, 43(6): 620-625. [百度学术]
陆明,吕春绪.氧平衡对粉状硝铵炸药爆炸性能影响的数学计算方法[J].兵工学报,2004(2):225-228. [百度学术]
LU Ming, Lü Chun‑xu. Mathematical calculation method of influence of oxygen balance on explosive performance of powdery ammonium nitrate explosive[J]. Acta Armamentarii,2004(2): 225-228. [百度学术]
ZHOU Xiang, ZHU Ying, CHENG Zhi‑peng,et al. Preparation of cyclotrimethylenetrinitramine‐copper oxide core‐shell particles and their thermal decomposition kinetics[J]. Propellants, Explosives, Pyrotechnics,2019,44(11): 1368-1374 [百度学术]