Evaluation of some thermal,mechanical and explosive properties of plastic bonded explosives based on epoxy resin

Abstract

RDX/HMX based Plastic Bonded Explosives (PBXs) with epoxy resin as a binder have been formulated and studied in detail for their explosive, mechanical and thermal properties. The effect of pressure on the moulding powder has also been optimized to achieve maximum loading density and compression strength. Further, these PBXs have been analysed for homogeneity and coating of binder over RDX/HMX crystals. The data suggest that epoxy resin based PBXs have higher loading density, higher mechanical strength and higher velocity of detonation (VOD) as compared to polyurethane based PBXs.     

An Investigation into the Effects of Additives on Crystal Characteristics and Impact Sensitivity of RDX

Additives are one of the most important factors that greatly affect the crystal characteristics of the high energy compound hexahydro-1,3,5-trinitro-1,3,5-s-triazine (RDX, C₃H₆N₆O₆) and they have an influence on impact sensitivity. In this article, a growth morphology method was applied to obtain the crystal habit of RDX in a vacuum as well as the morphologically important faces, and molecular dynamics simulations were applied to calculate the interaction energy between these crystal faces and additive molecules for prediction of the additive-effect crystal habits of RDX. On this basis, crystal characteristics including crystal morphology, aspect ratio, and total surface charge were investigated. Then the particle size and surface electrostatic voltage of the samples from recrystallization were analyzed experimentally. The impact sensitivity test indicated that acrylamide, which could enhance the regularity and degree of sphericity of RDX crystals and effectively reduce the surface static electricity of RDX, was successful in reducing the impact sensitivity of RDX as an additive for crystallization. The above experimental results were in good agreement with the conclusions based on the theoretical calculations.     

Preparation and Structure Study of Water-Blown Polyurethane/RDX Gun Propellant Foams

Water-blown polyurethane/RDX foamed propellants were prepared using polyols and isocyanate as reactive binder system, hexogen (RDX) as energetic component, triethanolamine (TEA)/Ditin butyl dilaurate (T-12) as composite catalysts, and H₂O as blowing agent. The influences of catalyst ratio, blowing agent amount, and solid filler content on the inner porous structure were studied. The results show that the balance of gel rate and cream rate that could be adjusted by catalyst ratio is a major influencing factor on porous structure of foamed propellants. When the ratio of TEA/T-12 was adjusted to 1/0.7, the morphology of the foamed propellant exhibited spherical and closed porous structure. Besides, when the water amount was increased from 0.1% to 0.5%, the pore size increased from 0.43 to 0.64 mm. The contents of RDX particles affected the cell nucleation and thus, the cell geometry. When the blowing agent amount was constant, the increased content of RDX filler led to a decreased pore size. The closed bomb test results showed that foamed propellants burned progressively in an in-depth combustion mode.     

新型仿金属高分子修复材料的研制

采用混合刚玉磨料与复配的粘合剂为基料,聚酰胺树脂和二乙烯三胺及一定量的B型增粘剂和无机填料得到的复配物为固化剂,制备了一种性价比较好的仿金属高分子修复材料。经正交实验确定其主要组成为基料中混合刚玉磨料(颗粒度65μm与55μm,质量比1:1,机械混合)与混合粘合剂的质量比为O.8:1;固化剂由聚酰胺树脂和二乙烯三胺按质量比1:2复配,加入B型增粘剂和适量无机填料;使用时固化剂和基料按1:5的质量比混合,将其应用于在线修复金属设备及机械零件,其粘接强度、抗冲击强度和耐磨性(磨耗量)分别为416 MPa,0.450 J/cm~2和10.3 mg,均超过进口修复材料(对应各项指标为384 MPa,0.403 J/cm~2和12.8 mg)的水平。     

Microstructure effects on the detonation velocity of a heterogeneous high-explosive

ABSTRACT

Although numerous methods exist for the theoretical calculation of detonation parameters of explosives, few thermodynamic-hydrodynamic-based theoretical codes take into account particle size. The basis for their computational analysis is primarily focused on the equation of state of the detonation products, heat of formation, and density of the explosive composition. This study utilized regression analysis to model the relationship between the microstructure characteristics and detonation velocity of a heterogeneous high-explosive composition containing cyclotrimethylene-trinitrmaine (RDX). The principal characteristics examined were the average particle size of RDX, amount of HMX impurity within the RDX particles, method of RDX manufacture, and compositional density. Statistical analysis demonstrated the relevancy of the microstructure influence on the detonation velocity of the developed experimental compositions of 73 wt. % solids and 27 wt. % polyurethane binder. An equation is developed that accurately predicts detonation velocity based on average particle size, density, and manufacturing process for RDX. The model underscores the significance of the relationship between the average particle size and detonation velocity. Compositions containing smaller average particle sizes of RDX generate higher detonation velocities. A 100 micron increase in the average particle size was shown to decrease detonation velocity by 161 m/s for the monomodal polyurethane compositions used in this study. The relevance of using statistical models for selecting characteristics that result in optimum explosive performance is addressed.     

A Successive and Scalable Process for Preparing Spherical Submicrometer-Sized RDX by the SEDS Process

The preparation spherical and submicrometer-sized cyclotrimethylene-trinitramine (RDX) is described through the process of solution-enhanced dispersion by supercritical fluids (SEDS). Because SEDS is a successive and scalable process, about 40.5 g RDX particles can be obtained within 70 min and the total yield is about 90.0% under optimized conditions. Submicrometer-sized RDX and original samples were characterized and confirmed by different analysis methods. The results revealed that submicrometer-sized RDX particles are spherical with a mean particle size of 767.7 nm, have high purity, show no crystal structure change, and decompose easily. Mechanical sensitivity tests of submicrometer-size RDX were decreased in comparison to the original RDX.     

宝浪油田煤层封堵剂配方及其性能

研制了以水溶性热固树脂、耐温聚合物、超微粉体颗粒增强剂及延迟剂组成的煤层封堵剂,并对封堵剂性能进行评价。结果表明,该封堵剂初始粘度低,流动性能好,成胶时间可调;可渗入煤层孔缝与煤层胶结性能好,固化后具有吸水微膨胀性能,能压实软煤层;煤层封堵剂耐高温、高压和高矿化度,耐腐蚀性能强,具有较高的成胶强度和封堵能力,封堵率达99．6％以上。     

KAUST-8晶体尺寸的调控及其吸水性能

通过采用向合成液中加入醇类添加剂的方法调控MOFs材料粒径,成功制备了纳米级金属有机骨架材料KAUST-8.采用X射线衍射(XRD)、热场发射扫描电子显微镜(SEM)及粒度分析等检测手段对KAUST-8的晶体结构、形貌和尺寸进行了表征,并探索了不同尺寸KAUST-8晶体的吸水性能.结果表明:随着介质中乙醇的体积分数从0...     

3-Nitro-1,2,4-triazol-5-one,a less sensitive explosive

A new, less sensitive explosive has been prepared and subjected to preliminary characterization tests. The compound, 3-nitro-1,2,4-triazol-5-one (NTO) has a crystal density of 1.93 g/cm³ and calculated detonation velocity and pressure equivalent to those of RDX. Results from initial small-scale sensitivity tests indicate that NTO is less sensitive than RDX and HMX in all respects. A 4.13-cm-diam, unconfined plate-dent test at 92% of crystal density gave the detonation pressure predicted for NTO by the BKW calculation. Finally, NTO can be prepared in high yield from inexpensive starting materials.     

Shock Initiation Characteristics of an Aluminized DNAN/RDX Melt-Cast Explosive

Shock sensitivity is one of the key parameters for newly developed, 2,4-dinitroanisole (DNAN)-based, melt-cast explosives. For this paper, a series of shock initiation experiments were conducted using a one-dimensional Lagrangian system with a manganin piezoresistive pressure gauge technique to evaluate the shock sensitivity of an aluminized DNAN/cyclotrimethylenetrinitramine (RDX) melt-cast explosive. This study fully investigated the effects of particle size distributions in both RDX and aluminum, as well as the RDX’s crystal quality on the shock sensitivity of the aluminized DNAN/RDX melt-cast explosive. Ultimately, the shock sensitivity of the aluminized DNAN/RDX melt-cast explosives increases when the particle size decreases in both RDX and aluminum. Additionally, shock sensitivity increases when the RDX’s crystal quality decreases. In order to simulate these effects, an Ignition and Growth (I&G) reactive flow model was calibrated. This calibrated I&G model was able to predict the shock initiation characteristics of the aluminized DNAN/RDX melt-cast explosive.     

Quantitative evidence for nitroso compound formation in drop-weight impacted RDX crystals

Abstract

Quantitative results are presented for the formation of two nitroso compounds during the drop-weight impact of Holston production-grade Class D RDX explosive crystals. Gas chromatography, using a sensitive Ni-63 electron capture detector, was employed to analyze “RDX residues” recovered from impact tests involving a 5 kg mass dropped from 10, 12, and 14 cm heights. The compounds, 1,3,5-trinitroso-1,3,5-triazacyclohexane (R) and 1,3-dinitroso-5-nitro-1,3,5-triazacyclohexane (RO) were detected at levels of (0·80 to 9·3) × 10^?10 percent and (1·3 to 560) × 10^?10 percent, respectively. More RO than R was formed at the 14 cm drop height. This appears to be the first time that nitroso compounds structurally similar to RDX have been observed in impacted RDX crystals.     

鄂尔多斯盆地三叠系延长组富有机质页岩孔隙特征及发育机制

页岩储层孔隙发育特征是页岩储层评价的重要内容,也是开展页岩油气赋存机理研究的基础。提出了通过“基质类型—孔隙产状—孔隙成因”划分孔隙类型的方案。利用氩离子抛光和场发射扫描电镜技术观察孔隙发育情况,根据基质类型和孔隙产状,识别了4类孔隙：粒间孔、粒内孔、有机质孔和微裂缝,并根据孔隙成因将粒间孔分为碎屑颗粒间原生孔、黏土矿物片体间孔和颗粒间溶蚀孔,将粒内孔分为长石颗粒内溶蚀孔、黏土矿物片体内孔和黄铁矿晶体间孔。有机质孔主要为有机质颗粒内的微裂缝和有机质内孤立分布的孔径较小的孔隙。微裂缝主要表现为纹层缝或页理缝。综合孔隙图像分析、低温液氮吸附实验结果、孔隙结构参数与矿物组成、有机碳含量和有机质成熟度等参数相关性分析,认为沉积条件、成岩作用和有机质热演化控制了孔隙的形成和保存。半深湖—深湖沉积环境下,富有机质页岩中发育重力流成因的薄层砂质纹层,纹层段碎屑颗粒含量高,有利于形成碎屑颗粒粒间孔、碎屑颗粒粒内孔和顺层微裂缝。早期成岩作用阶段形成黄铁矿,有利于形成黄铁矿晶间孔,但黄铁矿也是压实作用的主要参与者;压实作用造成粒间孔和粒内孔的孔径变小和孔体积降低,碎屑颗粒和黄铁矿与有机质颗粒间呈凹凸接触,有机质孔在压实作用下闭合导致有机质孔不发育;溶蚀作用促进长石粒间溶孔和长石粒内溶孔的形成,一定程度改善储层质量。在成熟度达到一定阶段(R_O≈0.75%)后,开始出现有机质孔。有机质孔发育程度差,一方面受成熟度的影响,另一方面可能是压实作用造成的。此外,富有机质泥页岩渗透性较差,烃类被吸附在有机质表面或溶于干酪根内部,造成干酪根体积膨胀也可能是有机质孔不发育的一种原因。     

砂岩成分对储层孔隙结构及天然气富集程度的影响——以苏里格气田西区二叠系石盒子组8段为例

鄂尔多斯盆地苏里格气田西区二叠系石盒子组8段是典型的致密砂岩储层,同时又具有低效充注、普遍产水的特点,其天然气有利勘探区的寻找不仅依赖于优质储层的预测,还需要对储层的含气性进行分析。为此,利用扫描电镜、CT扫描、覆压孔渗、激光拉曼等技术手段,对该区不同类型砂岩的微观特征差异及其对天然气富集程度的影响进行了研究。结果表明:(1)该区盒8段发育岩屑石英砂岩与岩屑砂岩2种类型储层,由于岩屑颗粒密度小且易破碎,在强水动力作用下不易富集,因此岩屑砂岩以细粒沉积为主;(2)岩屑石英砂岩中主要发育残余粒间孔与铸模孔,其喉道为石英颗粒间的孔隙,渗透率在覆压下损失小,而岩屑砂岩主要发育微孔,喉道以杂基内束状喉道为主,渗透率在覆压下损失大;(3)天然气充注时,岩屑砂岩经过压实作用已完成致密化,不利于天然气充注,而相反,因石英次生加大而致密的岩屑石英砂岩,天然气充注时其致密化过程尚未完成,物性与孔隙结构优于现今,是天然气的优势富集区。     

累积工况下CO2对稠油热采水泥石的修复作用

根据稠油火烧水泥石在井下先经历蒸汽吞吐、蒸汽驱,再经历稠油火烧的实际工况,利用超高温水泥石养护装置及高温高压腐蚀釜,研究累积工况下CO₂对水泥石抗压强度及腐蚀深度的变化规律;同时,利用XRD和SEM等技术探明了CO₂对水泥石化学结构及微观形貌的影响。实验结果表明,水泥石经常温及高温养护后呈现高孔渗、低强度的特征,但累积工况下经CO₂腐蚀釜养护后,抗压强度不减反增,到28 d时已升至53.4 MPa,较蒸汽驱后提高了54.87%;而随着CO₂腐蚀龄期的延长,水泥石腐蚀深度逐渐加深,结构更为致密,且28 d后已被完全碳化。究其原因,水泥石经CO₂腐蚀后,腐蚀产物CaCO₃溶解度较低,并在孔隙中沉淀结晶,堵塞毛细孔或将大孔分割成小孔,使水泥颗粒密实度提高。该研究结果可进一步丰富业界对CO₂腐蚀的认识,同时也为稠油火烧水泥浆体系的性能评价、配方优化提供参考。      

紧密堆积优化固井水泥浆体系堆积密实度

紧密堆积技术是高性能固井水泥浆体系设计关键技术,对提高固井水泥浆性能具有重要意义,其核心是提高颗粒体系的堆积密实度。为此,选用可压缩堆积模型作为紧密堆积理论模型,确定了模型参数和数值计算方法,编制了堆积密实度计算程序并对计算结果进行了验证;通过计算多元颗粒体系的堆积密实度,对影响颗粒体系堆积密实度的因素进行了分析,并进行了水泥浆设计和性能试验。研究结果表明,适当增加超细颗粒组分、合理优化粒径分布区间、提高颗粒体系的大小颗粒平均粒径比可以有效提高堆积密度,相比三元体系,含有纳米材料的五元体系可达到颗粒体系的最紧密堆积,水泥浆性能更好。利用紧密堆积模型指导油井水泥体系干混配比设计具有可行性。     

CT技术在致密砂岩微观孔隙结构研究中的应用——以鄂尔多斯盆地延长组长7段为例

为揭示致密砂岩复杂的孔隙结构特征,应用高分辨率CT技术,对鄂尔多斯盆地延长组长7段致密砂岩样品开展了定量研究。利用CT阈值差异识别样品中的孔隙和喉道,从而获得致密砂岩高精度二维及三维孔喉图像;应用数字岩心方法建立致密砂岩孔隙网络模型,并根据模型中的定量参数分析,获得孔隙及喉道的半径分布及其对储集空间的贡献率、孔喉连通性等特征,实现了长7段致密砂岩微观孔隙结构特征定量表征：长7段致密砂岩微米级孔喉连续分布;半径大于2 μm 的孔隙是长7段致密砂岩的主要储集空间;孔隙、喉道间具有一定的连通性,配位数主要为1~3. 应用高分辨率CT技术可定量表征致密砂岩孔隙结构特征。     

碳酸盐矿物溶蚀对页岩孔隙的改造作用及其意义——以川东地区下志留统龙马溪组页岩为例

碳酸盐矿物与页岩气储层的孔隙结构密切相关,探讨二者之间的定量关系有助于深化对页岩岩石学定量表征与微米/纳米尺度孔隙改造等的认识。为此选取四川盆地东部彭水地区下志留统龙马溪组页岩,开展了稀盐酸—页岩酸岩反应实验;综合利用场发射电镜、微CT以及低压氮气吸附方法,表征溶蚀前后孔隙结构;研究碳酸盐矿物对页岩储层孔隙结构的影响,进而探讨溶蚀孔的地质、工程指示意义。研究结果表明：①常温下酸岩反应120 h,碳酸盐矿物完全溶蚀而其他矿物则无明显变化;②碳酸盐矿物完全溶蚀后,出现大量孔径介于3.9~62.5 μm的溶蚀孔,溶蚀孔总体积分数占比为6.8%,与样品酸溶率数值6.9%接近,同时纳米孔的形态、体积、孔径、表面积等参数未发生明显的变化;③碳酸盐矿物完全酸溶后仅产生微米孔,而在纳米尺度未表现出增孔、扩孔现象,表明碳酸盐晶粒处于微米尺度。结论认为,基于微米级溶蚀孔的图像统计参数,可以有效反演碳酸盐矿物的微观分布、形貌、数量、粒径等特征参数,为页岩岩石学定量研究提供了一种新的方法,同时该溶蚀孔协同水力压裂缝网,有助于加速页岩气的产出。     

微孔防砂筛管的研制与应用

针对辽河油田稠油油藏的出砂情况及现有防砂工艺中存在的防砂后筛管易被泥质及原油中的胶质堵塞、防砂有效期短等周期,研制成带有衬管（保护管）的防砂筛管总成,用于油水井的防砂。微孔筛管由于选用刚玉砂作为制作的基质颗粒,其颗粒表面光滑且对原油润滑角小于临界值。该防砂筛管可耐高温、强酸、强碱,且避免了原油通过其孔隙在其晶体表面的聚集,防砂后不易堵塞,具有滤砂性能好、防砂有效期长、施工方便快捷、防砂施工成本低等优点,特别适用于稠油及特稠油防砂后注汽开采。在现场应用21井次,防砂施工成功率100%,防砂有效率90.47%,经济效益显著。实现了微孔 孔隙两级过滤和筛管单体间柔性联接两大技术突破。     

Non-isothermal crystallization kinetics of waxy crude oil

The crystallization behavior of Shengli waxy crude oil from the sol state to gel state was studied by the microscopic observation and DSC curve. The study shows that as the cooling rate decreases, the number of wax grains becomes smaller, the area is larger and the morphology of wax crystals is more irregular. Moreover, under different cooling rates, wax crystals were homogeneous transient nucleation, but the growth mode of wax crystals was different. When the cooling rate is between 1–4?°C/min, Crystallization Peak 1 wax crystal grows according to the mixed crystal mode of one-dimensional rod crystal and two-dimensional discoid crystal; When the cooling rate is between 6–8?°C/min, Crystallization Peak 1 wax crystal grows according to the mixed crystal mode of two dimensional discoid crystal and three-dimensional spherical crystal; Crystallization Peak 2 wax crystal grows according to the mixed crystal mode of two dimensional discoid crystal and three-dimensional spherical crystal at different cooling rates. Crystallization activation energy of crystallization Peak 1 and Peak 2 are 556.91?kJ/mol and 299.62?kJ/mol, respectively.     

Electrospray Preparation and Properties of RDX/F2604 Composites

This article was an attempt to prepare energetic materials based on 1, 3, 5-trinitro-1, 3, 5-triazinane (RDX) using the electrospray method to expand its scope of application. After preparation, the morphologies and crystal structures of the samples were characterized, and thermal decomposition properties as well as mechanical sensitivities were also investigated. The sizes of the composite particles were found to be in the range of 2–4 μm. Compared with raw RDX, the crystal structures of the RDX/F2604 composites were unchanged. The activation energy of the composites was decreased with the increase of the F2604 mass ratio, and 10 wt% F2604 composites had the lowest activation energy. In the mechanical sensitivity aspect, the impact sensitivity and friction sensitivity of the RDX/F2604 composites were lower than those of raw RDX. 10 wt% F2604 composites had the highest H₅₀ (65.9 cm) and the lowest friction sensitivity (76%).