Research on the Size of Defects inside RDX/HMX Crystal and Shock Sensitivity

Intragranular defects inside RDX/HMX were studied by optical microscopy with matching refractive (OMS), sink‐float method (SFM), and micro‐focus CT (μCT) techniques. OMS results revealed the phenomenon that RDX/HMX had more defects and cracks than RS‐RDX/RS‐HMX. μCT results indicated that RDX/HMX had more defects with larger volume than RS‐RDX/RS‐HMX. The gap test showed that critical shock pressure/gap thickness was 6.4 GPa/19.4 mm for PBX based on RDX, while they were 7.5 GPa/17.5 mm and 8.6 GPa/16.2 mm for PBX based on M‐RDX and RS‐RDX, respectively. Meanwhile, an analysis of the relationship between defects inside RDX/HMX crystal and shock sensitivity was made. Finally, the shock pressure response under impact loading was investigated by discrete element method.     

Micro Videographic Analysis of the Melt Layer of Self‐Deflagrating HMX and RDX

Micro videographic analysis of the thin molten layer on the surface of HMX (Octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine) and RDX (Hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine) during self deflagration were performed. This was done to gain a better understanding of the physical structure present in this 100–300 μm layer and give a visual picture for the development of computational models. During steady‐state combustion, RDX had a consistent melt layer with vigorous bubble formation. There was a continuous liquid layer throughout combustion and no foam was formed. The surface of HMX during steady‐state combustion at ambient initial temperatures was an uneven layer of foam. Foam appeared to convect across the surface in undulating waves. At elevated initial temperatures, the HMX molten layer was a consistent foam layer in both time and space. Micro videography was also done with a diagnostic laser sheet as illumination to measure the melt layer thickness. The RDX bubbling layer was about 217±30 μm thick. The HMX foam thickness varied from almost nothing to 660 μm, with an average value of about 234±106 μm.     

Stationary phases. Part 39(1): Trace analysis of RDX in HMX on a novel copoly(vinylthiazole-vinylimidazole) stationary phase by HPLC

A method for the HPLC analysis of RDX and HMX on a novel copoly(vinylthiazole-vinylimidazole) stationary phase [P(Th-Im) phase] is described. Special elution order of RDX and HMX on this phase using methanol/water (60/40∼90/10) as mobile phase is HMX > RDX, which is quite different from those on a commercial RP-18 phase. The chromatographic selectivities (α-values) between RDX and HMX are 2.40∼2.55. This advantage can be used to identify the limited impurity of ca. 1 ppm RDX in HMX during the manufacture of HMX.     

近红外光谱法测定HMX中α-HMX杂质晶型的含量

为了快速检测HMX中杂质晶型α-HMX的含量,在制备建模样品的基础上,利用近红外光谱技术,采用偏最小二乘法建立了HMX光谱与其α-HMX杂质晶型含量的计算模型。讨论了建模样品的代表性、模型光谱范围的选择及模型的优化过程。结果表明,模型具有广泛代表性,最佳光谱范围为6 476~6 446cm-1和4 602~4 424cm-1,交互验证决定系数(R2)为0.996,参考值交互验证残差均方根(RMSECV)为0.20%;外部验证的残差均方根(RMSEP)为0.27%;该法误差均小于0.13%,标准偏差为0.1%;近红外光谱法操作简单、快速、无损、绿色环保,可用于HMX中α-HMX杂质晶型含量的检测。     

老化对TNT基熔铸炸药性能的影响

为了研究老化对炸药性能的影响,对自然贮存的3种熔铸炸药TNT／RDX、TNT／RDX／Al和 TNT／HMX／Al进行了加速老化试验。通过扫描电镜、真空安定性试验研究了老化前后3种炸药的微观形貌和安全性能,并测试了老化前后3种炸药的感度和爆速。结果表明,老化后炸药颜色变深,体积膨胀,质量变轻。样品的放气量小于2 mL／g ,热感度变化也较小。机械感度的变化与炸药组分和老化方式有关。TNT／RDX的爆速随着贮存时间的增加而降低,与整体加速老化情况一致,TNT／RDX／Al和 TNT／HMX／Al的爆热随贮存时间的增加变化趋势相反,说明两者老化机理可能不同。     

RDX and HMX with Reduced Sensitivity Towards Shock Initiation–RS‐RDX and RS‐HMX

Reduced Sensitivity RDX (RS‐RDX) has received a lot of attention and interest from the explosive community in the recent years. There are several producers of RS‐RDX, most of them using a direct nitration (Woolwich process) for the RDX synthesis, while Chemring Nobel uses the Bachmann process. The processes for obtaining the RS properties probably differ between the various producers. Chemring Nobel has also developed an HMX quality that shows Reduced Sensitivity (RS‐HMX) of different particle size distributions. The shock sensitivity is at the same level as for RS‐RDX in comparable compositions. Reduced shock sensitivity has been obtained for RS‐RDX and Reduced Sensitivity (RS‐HMX) in both pressable and cast‐cured compositions. By using a pressable composition, it is possible to get the results from a BICT gap test faster than from a cast‐cured composition that has to go through a curing process. Chemring Nobel in cooperation with FFI have performed an extensive accelerated ageing testing of RS‐RDX produced by the Bachmann process. The samples have been aged at 60 and 70 °C and the shock sensitivity tested by two different gap tests. The results demonstrate that the Chemring Nobel RS‐RDX retain the insensitivity towards shock during ageing and show no degradation at all. Accelerated ageing testing of RS‐HMX has also been performed and shows no degradation in the shock sensitivity.     

Degradation of TNT,RDX, and HMX Explosive Wastewaters Using Zero‐Valent Iron Nanoparticles

The high‐energy explosives 2,4,6‐trinitrotoluene (TNT), hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX), and the high melting explosive octahydro‐1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocine (HMX) are common groundwater contaminants at active and abandoned munitions production facilities causing serious environmental problems. A highly efficient and environmentally friendly method was developed for the treatment of the explosives‐contaminated wastewaters using zero‐valent iron nanoparticles (ZVINs). ZVINs with diameters of 20–50 nm and specific surface areas of 42.56 m² g⁻¹ were synthesized by the co‐precipitation method. The explosives degradation reaction is expressed to be of pseudo first‐order and the kinetic reaction parameters are calculated based on different initial concentrations of TNT, RDX, and HMX. In addition, by comparison of the field emission scanning electron microscopy (FE‐SEM) images for the fresh and reacted ZVINs, it was apparent that the ZVINs were oxidized and aggregated to form Fe₃O₄ nanoparticles as a result of the chemical reaction. The X‐ray diffraction (XRD) and X‐ray absorption near edge structure (XANES) measurements confirmed that the ZVINs corrosion primarily occurred due to the formation of Fe₃O₄. Furthermore, the postulated reaction kinetics in different concentrations of TNT, RDX, and HMX, showed that the rate of TNT removal was higher than RDX and HMX. Furthermore, by‐products obtained after degradation of TNT (long‐chain alkanes/methylamine) and RDX/HMX (formaldehyde/methanol/hydrazine/dimethyl hydrazine) were determined by LC/MS/MS, respectively. The high reaction rate and significant removal efficiencies suggest that ZVINs might be suitable and powerful materials for an in‐situ degradation of explosive polluted wastewaters.     

EAK基熔铸分子间炸药的能量和撞击感度

通过水下爆炸试验研究了RDX和HMX对EAK基熔铸分子间炸药水下能量的影响。结果表明,RDX和HMX对EAK基混合炸药起到明显的增能作用,但对含铝和非含铝体系有不同的作用效果。爆速和撞击感度测定表明,EAK—RDX混合炸药爆轰的理想化程度和稳定性及撞击感度随RDX含量的增加而增加。从能量和撞击感度两个方面综合考虑,RDX的较佳加入量应为20％～30％。     

Multivariate Calibration of Semi‐Synthetic Data Sets: Gun Powder Analysis

Quantitative analysis of multi‐component mixtures such as propellant powders is not trivial since it usually requires separation of the mixture constituents. Multivariate calibration combined to the use of semi‐synthetic data sets can eliminate the need for standard solutions preparation, and therefore allow the rapid determination of mixtures provided no intermolecular interactions occur in the systems. Multivariate compositional analyses of FTIR spectra of low‐vulnerability (LOVA), high‐energy low‐vulnerability (HELOVA) and energetic thermoplastic elastomer (ETPE) propellant powder systems were performed using the partial least‐squares (PLS) regression algorithm. All constituents except ethyl centralite (EC) were quantified. Concentrations were predicted within 1% error for the major component (1,3,5‐trinitro‐1,3,5‐triazacyclohexane or RDX), and within 5% error for the minor components (between 12 and 2% nominally by weight). LOVA, HELOVA, and ETPE gun powder samples concentrations were estimated and compared to expected compositions.     

Modifying the Wettability of Nitramine Explosives using Anionic,Cationic and Nonionic Surfactants

Wetting behavior of energetic materials surface including cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine (HMX) and hexanitrohexaazaisowurtzitane (CL‐20) using nonionic (Triton‐X), anionic (SDS), and cationic (TTAB) surfactants has been studied by contact angle tensiometry. Results show that TTAB more significantly reduces the contact angle and improves wettability as compared to SDS and Triton‐X. The liquid‐vapor surface tension was measured as a function of TTAB surfactant concentration in aqueous solutions and used to construct a Zisman plot to determine the critical surface tension of RDX, HMX and CL‐20. The results show that HMX displays the highest degree of wettability while RDX is most difficult to wet. The computed values of the work of spreading complement the previously discussed results where contact angle decreases with increasing surfactant concentration. They also indicate that RDX appears most impacted by the addition of TTAB surfactant. However, the addition of TTAB also has a significant impact on improving the wettability of HMX and CL‐20. This wettability study plays an important role in the formation of well‐wetted energetic surfaces needed for efficient wet milling, coating and granulation processes.     

Na_2·cis-BNT和G_2·trans-BNT与几种含能材料相互作用的热分析

采用差示扫描量热法(DSC)并结合热重-微商热重法(TG-DTG)研究了双(3-(5-硝基-1,2,4-三唑))的钠盐(Na_2·cis-BNT)和胍盐(G_2·trans-BNT)与黑索金(RDX)、奥克托今(HMX)及3,3-双叠氮甲基氧丁环-聚叠氮缩水甘油醚共聚物(BAMO-GAP)的相容性,及混合物体系的热行为。初步探索了样品制备方法 (研磨法与溶剂法)对混合物体系相容性的影响。结果表明,对Na_2·cis-BNT、G_2·trans-BNT采用干法和湿法制备得到的混合体系相容性结果有一定差异。用干法制备二元体系时,Na_2·cis-BNT/RDX体系相容,Na_2·cis-BNT/HMX体系为轻度敏感,适合短期使用;而G_2·trans-BNT/RDX体系为敏感,不适合使用,G_2·trans-BNT/HMX体系为不相容;用湿法制备二元体系时,Na_2·cis-BNT与RDX、HMX、BAMO-GAP的混合物及G_2·trans-BNT与BAMO-GAP的混合物为相容,而混合物G_2·trans-BNT/RDX、G_2·trans-BNT/HMX为敏感,不适合使用。非均相过程分解的HMX混合体系相容性会受混合方式的影响,因此,由DSC法测定相容性时,制样的混合方法需要明确说明,并应当结合其他方法作最后判定。     

Laboratory‐Scale Method for Estimating Explosive Performance from Laser‐Induced Shock Waves

A new laboratory‐scale method for predicting explosive performance (e.g., detonation velocity and pressure) based on milligram quantities of material is demonstrated. This technique is based on schlieren imaging of the shock wave generated in air by the formation of a laser‐induced plasma on the surface of an energetic material residue. The shock wave from each laser ablation event is tracked for more than 100 μs using a high‐speed camera. A suite of conventional energetic materials including DNAN, TNT, HNS, TATB, NTO, PETN, RDX, HMX, and CL‐20 was used to develop calibration curves relating the characteristic shock velocity for each energetic material to several detonation parameters. A strong linear correlation between the laser‐induced shock velocity and the measured performance from full‐scale detonation testing has been observed. The Laser‐induced Air Shock from Energetic Materials (LASEM) method was validated using nitrocellulose, FOX‐7, nano‐RDX, three military formulations, and three novel high‐nitrogen explosives currently under development. This method is a potential screening tool for the development of new energetic materials and formulations prior to larger‐scale detonative testing. The main advantages are the small quantity of material required (a few milligrams or less per laser shot), the ease with which hundreds of measurements per day can be obtained, and the ability to estimate explosive performance without detonating the material (reducing cost and safety requirements).     

纳米铝粉对硝胺炸药热分解催化性能的影响

采用直流电弧等离子体蒸发法制备了高纯度的纳米铝粉,并用比表面积分析仪和扫描电子显微镜(SEM)对样品进行了表征.将纳米铝粉与硝胺炸药HMX和RDX用研磨混合法制成混合粒子,用DSC对单质HMX和RDX炸药以及纳米铝粉/硝胺炸药混合物进行催化特性测试,并对样品的热分解动力学和热力学参数进行了计算和对比.结果表明,加入纳米铝粉后,HMX和RDX在不同升温速率(2、5、10、20 K/min)下的放热峰峰温降低,活化能分别降低15和16 kJ/mol,热力学参数都有明显变化.纳米铝粉对HMX和RDX有明显的热分解催化作用.     

Thermal Behaviour of HMX/RDX Mixtures

Thermal behaviour of HMS/RDX mixtures is studied by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). It has been found that the temperature of polymorphic transformation of HMX shows an increase due to the presence of RDX. The enthalpies of the enothermic transformations depend on the composition of the mixture, and up to 30% RDX there is a linear relationship. The formation of an eutectic with a composition of 30/70 (HMX/RDX) is postulated to explain the melting processes.     

用LC/APCI/MS方法检测粉尘中的炸药成分

采用高选择性和灵敏度的LC(液相色谱)/APCI(大气压化学电离源)/MS(质谱)方法定量分析粉尘样品中的HMX、RDX、PETN、CE、NQ和TNT。采用ASE萃取,GPC净化浓缩作为前处理方法,在粉尘中分别添加所测炸药组分,用丙酮作为ASE萃取溶剂,乙酸乙酯和环己烷(体积比为1∶1)作为GPC净化时的流动相并抛弃杂质500s,收集1 520s。在LC/MS分析时,通过在流动相中添加1mmol/L甲酸与样品形成[M+HCOO]-的甲酸加合离子。结果表明,HMX、RDX、PETN、CE、NQ、TNT的方法检测限分别为0.78,1.44,1.69,0.77,1.06,1.72ng/mL,回收率为49.0%～88.4%,相对标准偏差为3.5%～10.3%。该方法可以用来系统排查及定量分析爆炸残留物及环境样品中的NQ、RDX、PETN、CE、HMX、TNT成分。     

Optical Properties of Energetic Materials: RDX,HMX, AP,NC/NG,and HTPB

Optical properties of RDX, HMX, AP, HTPB/IPDI and a catalyzed NC/NG propellant (N5) were obtained from 2.5 μm to 18 μm using FTIR transmission spectrometry. Scattering-corrected KBr pellet methodology was used for the crystalline materials. Absorption index (k) was measured directly and refractive index (n) was deduced using dispersion theory. At 10.600 μm the absorption coefficients were AP, 190 cm⁻¹ (240 cm⁻¹ at 10.6036 μm); HTPB/IPDI, 360 cm⁻¹; N5, 510 cm⁻¹; RDX, 2800 cm⁻¹; and HMX, 5670 cm⁻¹.     

Study of Plastic Explosives based on Attractive Cyclic Nitramines Part I. Detonation Characteristics of Explosives with PIB Binder

Four plastic explosives based on energetic nitramines and a non‐energetic binder were prepared and studied. The nitramines were RDX (1,3,5‐trinitro‐1,3,5‐triazine), HMX (1,3,5,7‐tetranitro‐1,3,5,7‐tetrazine), BCHMX (cis‐1,3,4,6‐tetranitro‐octahydroimidazo‐[4,5‐d]imidazole) and HNIW (ε‐2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane, ε‐CL‐20). The binder was in all cases polyisobutylene (PIB) as in the standard composition C‐4. These powerful plastic explosives were compared to standard PETN‐based commercially available explosives Semtex 1A and Sprängdeg m/46. The detonation velocities were experimentally measured and compared to the ones calculated by the Kamlet–Jacobs method, CHEETAH and EXPLO5 Codes. The experimental detonation velocities as well as the calculated detonation parameters decrease in the following order: HNIW‐PIB>HMX‐PIB≥BCHMX‐PIB>RDX‐PIB>Sprändeg m/46≥Semtex 1A. Urizar coefficients for the various binders were calculated from experimental data.     

Anaerobic biodegradation of RDX and HMX with different co-substrates☆

Simulated wastewater of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) was treated under anaerobic conditions with co-substrates such as ammonium chloride, dex-trose, sodium acetic, sodium nitrate and sulfate. The results showed that with nitrogen compounds such as ammonium chloride added as co-substrate, no significant change was observed, indicating that the molar ratio of N/C for RDX and HMX is sufficient for biodegradation. With the addition of dextrose and acetate to the system, biodegradation efficiency was enhanced greatly. For example, with dextrose as the co-substrate, degradation efficiency of 99.1%and 98.5%was achieved for RDX and HMX, respectively, after treatment for 7 days. When so-dium acetic was used as the co-substrate, the enhancement of degradation percentage was similar, but was not as high as that with dextrose, indicating the selectivity of RDX and HMX to co-substrate during anaerobic degrada-tion. With sodium nitrate as the co-substrate, the degradation efficiency of RDX or HMX decreased with the increase of salt concentration. Sodium sulfate has no significant effect on the biodegradation of RDX and HMX. A wel-selected co-substrate should be employed in applications for degradation of RDX and HMX wastewaters.     

热红联用研究AP与RDX和HMX混合体系的热分解

用DSC—TG—FTIR（热红）联用研究了RDX／AP，HMx／AP，RDx／HMx和RDX／HMX／AP混合体系的热分解，测定和比较了它们的热分析特征量和分解气相产物。结果表明，AP与RDX和HMX之间存在强烈的相互作用，尤其是与后者的作用更强烈。在AP（不含碳）分解的温度区间，混合体系的分解也出现CO、CO2和CH2O等碳氧化物，说明体系中RDX和HMX分解的部分产物或残渣与AP同时分解。     

Aging of Standard and Insensitive RDX Crystals Investigated by Means of X‐Ray Diffraction

Coarse particles of the high explosive RDX in different qualities (S‐RDX, I‐RDX, VI‐RDX) were aged artificially in air and argon, equivalent up to 25 years at 25 °C. The samples were investigated by means of X‐ray diffraction and rocking curves, revealing the behavior of microstrain during the artificial aging. The investigations revealed that the improved crystal quality of RDX survives artificial aging in contrast to a standard quality, where aging increases microstrain significantly. Besides aging details and mechanisms on a crystal level are described and discussed, such as eutectic mixtures with HMX impurities, crystal growth, defect healing, surface diffusion and smoothing, and reconstruction of crystal faces, edges and corners in rounded particles.