Flash Lamps as Ignition and Initiation Sources of the VS-2 Pyrotechnic Composition

In the present work it is found that the pyrotechnic composition VS⁃2 can be initiated with flash lamps IFC⁃500 and EVIS.VS⁃2 pyrotechnic composition contains 90%of mercury(Ⅱ)5⁃hydrazinotetrazolate perchlorate and 10%of optically trans⁃parent copolymer of 2⁃methyl⁃5⁃vinyltetrazole and methacrylic acid(PVMT).We have found that the flash lamps make it possi⁃ble to initiate combustion of VS⁃2 composition with its transition to detonation both in cylindrical charges placed in brass caps of 5 mm diameter and 2 mm high,and film charges with 10 mm×80 mm in size and surface weights of 60 mg·cm^(-2)and 90 mg·cm^(-2),showing ignition delay times 10μs and 3μs,respectively.We also measured detonation velocities for VS⁃2 composition film charges,which were 4375-4505 m·s^(-1)(of the charge being surface mass 60 mg·cm^(-2))and 4221-4281 m·s^(-1)(of the charge be⁃ing surface mass 90 mg·cm^(-2))and their blasting action on the aluminum plate.The depths of the normal shock wave imprints at the charge⁃barrier interface were 0.6-0.7 mm(for surface mass of the film charges 60 mg·cm^(-2))and 1.2-1.3 mm(for surface mass of the film charges 90 mg·cm^(-2))

Preparation and wear properties of TiB_2/Al-30Si composites via in-situ melt reactions under high-energy ultrasonic field

TiB2/Al-30Si composites were fabricated via in-situ melt reaction under high-energy ultrasonic field. The microstructure and wear properties of the composite were investigated by XRD, SEM and dry sliding testing. The results indicate that TiB2 reinforcement particles are uniformly distributed in the aluminum matrix under high-energy ultrasonic field. The morphology of the TiB2 particles is in circle-shape or quadrangle-shape, and the size of the particles is 0.1-1.5μm. The primary silicon particles are in quadrangle-shape and the average size of them is about 10μm. Hardness values of the Al-30Si matrix alloy and the TiB2/Al-30Si composites considerably increase as the high energy ultrasonic power increases. In particular, the maximum hardness value of the in-situ composites is about 1.3 times as high as that of the matrix alloy when the ultrasonic power is 1.2 kW, reaching 412 MPa. Meanwhile, the wear resistance of the in-situ TiB2/Al-30Si composites prepared under high-energy ultrasonic field is obviously improved and is insensitive to the applied loads of the dry sliding testing.

Crystal phase control and ignition properties of HNS/CL-20 composite microspheres prepared by microfluidics combined with emulsification techniques

Improved controllability and energy density of ignition agents are of great significance for the devel-opment of energetic composite materials.In this study,droplet microfluidics and emulsification tech-niques were combined to prepare HNS/CL-20 composite microspheres with polyglycidyl azide polymer(GAP)as the binder.The influence of binder content on the morphology of microspheres was investi-gated,and the microspheres were characterized and tested for particle size,crystal structure,thermal decomposition,dispersibility,mechanical sensitivity,combustion behavior and detonation performance.The results showed that microspheres prepared with a binder content of 3%had higher sphericity and particle size uniformity.The microspheres retained the crystal structure of both HNS and CL-20(ε-type).Compared with raw HNS,the microspheres had higher apparent activation energy,better safety per-formance,and good dispersibility.The ignition experiments and detonation performance tests show that HNS/CL-20 composite microspheres have excellent ignition performance,obvious combustion flame,and significant energy release effects,which are expected to achieve high energy and high-speed response of the igniter,thus improving the ignition reliability in special environments or systems.

In situ(Mg_2Si+MgO)/Mg composites fabricated from AZ91-Al_2(SiO_3)_3 with assistance of high-energy ultrasonic field

In situ （Mg2Si＋MgO）/Mg composites fabricated from AZ91-A12（SiO3）3 under high-energy ultrasonic field were investigated by XRD, DSC and SEM. The results indicate that the size, morphology and distribution of the in situ Mg2Si particles are greatly optimized with the assistance of the high-energy ultrasonic field. The amounts of the in situ Mg2Si particles are increased, the sizes are refined, the distributions become uniform, and the morphologies are changed to smooth olive-shape or spherical shape. The amounts of brittle fl-Mgl7All2 phases are decreased and the morphologies are granulated. The values of the tensile strength ab and HB hardness are increased. These are due to the cavitation effects and acoustic streaming effects induced by the high-energy ultrasonic field.

Optimization of Process Parameters for in High-Energy Ball Milling of CNTs/Al2024 Composites Through Response Surface Methodology

The mathematical models are developed to evaluate the ultimate tensile strength( UTS) and hardness of CNTs / Al2024 composites fabricated by high-energy ball milling. The effects of the preparation variables which are milling time,rotational speed,mass fraction of CNTs and ball to powder ratio on UST and hardness of CNTs / Al2024 composites are investigated. Based on the central composite design( CCD),a quadratic model is developed to correlate the fabrication variables to the UST and hardness. From the analysis of variance( ANOVA),the most influential factor on each experimental design response is identified. The optimum conditions for preparing CNTs / Al2024 composites are found as follows: 1. 53 h milling time,900 r / min rotational speed,mass fraction of CNTs 2. 87% and Ball to powder ratio 25 ∶ 1. The predicted maximum UST and hardness are 273.30 MPa and 261.36 HV,respectively. And the experimental values are 283.25 MPa and256.8 HV,respectively. It is indicated that the predicted UST and hardness after process optimization are found to agree satisfactory with the experimental values.

Structure-function integrated magnesium alloys and their composites

Magnesium-based materials not only exhibit desirable characteristics such as low density and high specific strength, but also possess exceptional functional properties, including high damping capacity, high thermal conductivity, high electromagnetic interference shielding capacity, flame retardancy, and dissolvability. However, achieving a balance between strength and functional properties remains a significant challenge in Mg alloys community. Typically, strength depends on the pinning effect of defects, such as solute atoms and second phases,which hinder dislocation motion. On the other hand, optimal functional properties usually necessitate relative perfect crystal structures, as the presence of solute atoms and second phases can have adverse effects on damping capacity and thermal conductivity. Balancing these conflicting requirements is difficult. The trade-off between strength and functional properties of the Mg alloys should be broken to meet the urgent need in aerospace, automotive, 3C(computers, communications, and consumer electronics) and energy industries for high performance structural-functional integrated Mg-based materials. This review summarizes recent progress in understanding the mechanisms and influencing factors for the functional properties of Mg alloys. The mechanisms underlying the trade-off between strength and functional properties of Mg alloys is discussed. The latest developed structural-functional integrated Mg alloys and their composites are summarized, including high strength Mg-based materials with high damping capacity/high thermal conductivity/strong electromagnetic shielding capability/excellent flame-resistance/high dissolution rate. The future works of developing structure-function integrated Mg-based materials are proposed.

结构复合含能破片对柴油油箱的引燃试验研究

围绕Al/PTFE含能材料及其结构复合含能破片对柴油目标的引燃性问题,分别用动态冲击试验和枪发射试验研究了Al/PTFE、铝热剂及其混合配比材料的冲击反应特性及结构复合含能破片对柴油油箱的引燃性能。结果表明:Al/CuO比Al/PT-FE具有更低的反应激发速率,通过在Al/PTFE中添加Al/CuO能显著降低含能材料的冲击反应阈值。枪发射引燃柴油试验显示,分别以Al/PTFE、Al/PTFE-Al/CuO和Al/PTFE-2Al/CuO作为内部装料时,复合破片对柴油油箱持续引燃的速度阈值分别为1246、1171、1098 m/s。混合配比含能破片具有更高引燃能力的原因在于Al/CuO的加入降低了含能材料的整体发火阈值,同时提升了Al/PTFE的释能效率。

降速剂及其作用位点对三组元推进剂燃烧性能的影响规律研究

针对两种典型季铵盐和金刚烷衍生物降速剂,研究了其作用位点对推进剂点火燃烧性能的影响。基于两种不同结构的Al@AP和AP@Al复合颗粒,将降速剂分布在不同作用位置:即AP颗粒内部和表面。利用扫描电子显微镜(SEM-EDS)和计算机断层扫描(CT)等技术对所制备复合颗粒微观形貌和结构进行表征,研究了降速剂对推进剂爆热、点火延迟和燃烧性能的影响。惰性降速剂的加入会使得推进剂爆热值降低,但Al@AP复合颗粒的高反应活性能部分抵消这一现象。与机械混合方式相比,当降速剂作用于AP表面时能明显延缓推进剂点火过程,其中金刚烷衍生物能使推进剂点火延迟时间增加至420 ms,比基础配方增加了192%。在基体中直接加入降速剂可以有效降低推进剂燃速,但其降压强指数效果有限。铝基复合颗粒和降速剂的共同作用能显著降低推进剂的高压燃速和压强指数:当作用位置在AP内时,两种降速剂使推进剂1~20 MPa内压强指数从基础配方的0.45分别降低至0.20和0.33,同时可使10~20 MPa压强指数分别减小了48%和49%。

内/外隔热复合结构炸药装药快速烤燃热防护效应

为了研究快速烤燃(火烧)条件下炸药装药内/外隔热复合结构(内隔热材料/外阻燃材料)的热防护效应,对多种内/外隔热复合结构的炸药装药进行多点测温快速烤燃试验,得到火焰场和炸药装药各测点的温度-时间曲线及装药点火响应时间。开展内/外隔热复合结构炸药装药快速烤燃数值模拟,获得内/外隔热复合结构对装药快速烤燃点火响应时间的影响规律。研究结果表明:在快速烤燃过程中,外阻燃材料由于火烧变性存在导热增强及隔热减弱效应,在数值模拟中需考虑该效应;无论使用单独的隔热/阻燃材料还是使用内/外隔热复合结构,炸药装药的点火响应时间均随着材料涂覆厚度增加而延后,其中内/外隔热复合结构具有更好的热防护能力;点火位置均发生在装药端面棱角处,装药点火后反应烈度不受内/外隔热复合结构影响,反应等级均为爆燃;对于一定热防护性能范围内的隔热阻燃材料,壳体外表面涂层材料是耐高温纳米隔热材料、壳体内表面涂层材料是高效隔热防护材料时复合结构的隔热效果最好,并且当需求的隔热效果给定时,可考虑优先增加壳体外表面涂层的涂覆厚度,实现以最小涂覆厚度的内/外隔热复合结构满足所需的隔热效果。研究成果可为提升弹药热安全性设计提供参考。

硼基金属复合物的点火和燃烧特性研究进展

综述了近几年国内外硼基金属复合物点火和燃烧特性的最新研究进展,重点归纳了二元硼基金属复合物、三元硼基金属复合物和纳米硼基金属复合物的点火和燃烧研究现状,并对比了其优缺点,其中对二元硼基金属复合物的研究较为丰富,对三元硼基金属复合物的研究大多集中于制备方向,关于点火和燃烧特性研究较少,对纳米基金属复合物的点火燃烧机理尚不清楚。指出了硼基金属复合物未来的研究方向:(1)对于制备工艺较简单的二元硼基金属复合物,下一步应具体研究其工艺对产物性能的影响;(2)利用分子动力学和有限元分析的方法对其燃烧机理进一步分析;(3)关于纳米硼基金属复合物可考虑建立一种稳定悬浮液进一步探究其点火和燃烧机制。附参考文献71篇。

降速剂及其作用位点对丁羟四组元推进剂燃烧性能的影响规律

为研究降速剂对丁羟四组元推进剂燃烧性能的影响规律,将典型季铵盐和金刚烷衍生物两种高效降速剂引入核壳结构铝基复合颗粒Al@HMX和AP@Al,使其分别作用于HMX颗粒内部和AP颗粒表面,制备了4种含降速剂的铝基复合颗粒(Al/A@HMX,Al/B@HMX,AP@Al/A和AP@Al/B);采用扫描电子显微镜对样品形貌进行了表征;采用高速红外相机拍摄推进剂燃烧过程的火焰红外照片,并对推进剂的爆热、密度、点火延迟时间和燃速进行了测试。结果表明,加入惰性降速剂会导致推进剂爆热降低,而Al@HMX复合颗粒能部分抵消这一现象,使推进剂爆热值增加了338 J/g;降速剂能够抑制AP和HMX的热分解过程,使达到AlO辐射峰值前维持低强度的“平台段”;而引入Al@HMX后,推进剂的点火延迟时间比基础配方减小49.4%;在10~20 MPa范围内两种降速剂均能有效降低推进剂燃速,在此基础上采用Al@HMX可使含季铵盐丁羟四组元推进剂20 MPa下的燃速降低7.1 mm/s(38.4%),压强指数降至0.25;当降速剂作用于AP表面时,含质量分数1%季铵盐的推进剂在20 MPa下燃速可降低5.0 mm/s(27.3%)。

烧结料面裂缝产生原因及其与点火温度的关系

为保证烧结矿具有良好的冶金性能,同时提高料层透气性,本文通过分析料面裂缝的形状、长度和生长规律,研究裂缝产生的原因及其与点火温度之间的关系,采用光学显微镜查看裂缝处烧结矿的微观组织,并对裂缝处烧结矿进行力学分析。结果表明:在一定范围内,随着点火温度的升高,裂缝条数呈增加趋势,当点火温度大于1150℃时,裂缝条数反而呈减少趋势;随着点火温度的升高,裂缝产生的位置逐渐后移,即点火温度越高,裂缝的产生时间越晚;随着点火温度的升高,烧结矿中FeO质量分数呈下降趋势,但当温度超过1150℃后,烧结矿中FeO质量分数反而呈上升趋势;裂缝处烧结矿内有大量针状铁酸钙,存在适当的晶间裂缝和孔洞,且赤铁矿含量适中,质量优于内部的烧结矿;裂缝的产生能改善料层内部空气流通,增加料层透气性,进而改善烧结矿质量。理论计算结果表明,固熔物的斥力大于引力(F引<F斥),且固相物强度小于液相表面张力(ξ<ε竖)是裂缝产生的必要条件。本文研究成果可为改善实际烧结生产提供理论依据。

HTPB固体推进剂落锤撞击试验及点火响应模拟

HTPB复合固体推进剂在低幅值长脉冲压力作用下可能发生意外点火,进而发展成燃烧或爆轰导致严重后果。为研究HTPB复合固体推进剂药片在撞击作用下的受力状态及点火机制,建立了卡斯特落锤仪的冲击力测试系统,并获得了落锤撞击作用下推进剂药片特性落高值及其不同高度时药片的落锤冲击力载荷曲线。基于落锤撞击测试装置建模,开展推进剂药片的落锤撞击点火试验数值模拟。研究结果表明,药片在2 kg落锤下的特性落高值H50为29.5 cm,药片表面受到冲击力峰值36.9 kN及作用时间0.40 ms;数值模拟结果显示,药片发生点火的特性落高在28~30 cm之间,与试验结果相吻合;药片受到落锤冲击发生径向变形,且表面局部应力集中,同时HTPB粘结剂发生塑性流动及摩擦,导致药片局部点高温,直至诱发AP颗粒热分解发生点火响应;模拟计算得到了2 kg落锤撞击药片点火的压力峰值470.9 MPa,点火时间约为0.30 ms。

Research of Mechanical and Thermal Properties of Composite Material Based on Gypsum and Straw

This article is focused on the investigation of the mechanical and thermal properties of composite material that could be used for the production of plaster or plasterboards.This composite material is made of gypsum and reinforcing natural fibers.The article verifies whether this natural reinforcement can improve the investigated properties compared to conventional plasters and gypsum plasterboards made of pure gypsum.From this composite material,high-strength plasterboards could then be produced,which meet the higher demands of users than conventional gypsum plasterboards.For their production,natural waste materials would be used efficiently.As part of the development of new building materials,it is necessary to specify essential characteristics for their later use in civil engineering.Crushed wheat straw and three gypsum classes with strengths G2(2 MPa)—gypsum Class I.,G5(5 MPa)—gypsum Class II.and G16(16 MPa)—gypsum Class III.were used to create the test samples.Samples were made with different ratios of the two ingredients,with the percentages of straw being 0%,2.5%,and 5%for each gypsum grade.The first part of the article describes how the increasing proportion of straw affects the composite’s mechanical properties(flexural strength and compressive strength).The second part of the article focuses on the change of thermal properties(thermal conductivity and specific heat capacity).The last part of the article mentions the verification of the fire properties(single-flame source fire test and gross heat of combustion)of this composite material.The research has shown that the increasing proportion of straw reinforcement caused a deterioration in the flexural strength(up to 56.49%in the 3.series of gypsum Class II.)and compressive strength(up to 80.27%in the 3.series of gypsum Class III.)and an improvement in the specific heat capacity and thermal conductivity(up to 31.40%in the 3.series).This composite material is thus not suitable for the production of high-strength plasterboards,but its reduced mechanical properties do not prevent its use for interior plasters.Based on the performed fire tests,it can be said that this composite material can be classified as a non-flammable material of reaction to fire Classes A1 or A2.From an ecological point of view,it is advantageous to use a composite material with a higher straw content.

基于细观结构的复合固体推进剂含损伤黏弹性本构模型

复合固体推进剂的宏观力学性能与其细观组分及损伤密切相关,基于复合固体推进剂变形过程中细观结构的演化,开发复合固体推进剂含孔洞损伤的宏细观本构模型。该模型考虑了推进剂温度和应变率的相关性,并能够描述推进剂拉伸和压缩状态下不同的力学响应。通过不同温度和不同应变率下的拉伸和压缩试验,验证本构模型的有效性。基于有限元分析软件提供的用户材料子程序接口UMAT,对非线性黏弹性本构模型进行二次开发,并应用于低温点火工况下药柱结构完整性分析,结果表明药柱在低温点火条件下安全系数为2.56,结构完整性满足要求。与基于Prony级数的线性黏弹性本构模型进行对比分析,表明新建立的本构模型能够更准确地进行复合固体推进剂药柱的结构分析。

微尺寸半导体桥电容发火特性研究

为了获得微尺寸半导体桥电容发火的特征参数与设计参数的关系,对20μm×50μm×4μm 60°的半导体桥进行了不同掺杂浓度、发火电容、发火电压及两种点火药剂下的发火试验,获得设计参数与半导体桥的特征能量、特征时间的关系。结果表明:半导体桥的发火电容值从10μF增大到68μF时,高掺杂的半导体桥/斯蒂芬酸铅的最小全发火电压为6.23~4.28V,比低掺杂的半导体桥降低了0.86~1.52V;半导体桥发生电爆所需的电能随着掺杂浓度的提高而减小,但与电压值、电容值、药剂种类无关;发生电爆所需的时间随着电容值、电压值、掺杂浓度提高而缩短;等离子体加热时间和能量随着电容值、电压值、掺杂浓度提高而增大。

Activation of anthracite combustion by copper acetate:mechanism,effect of particle size and introduction method

This paper addressed the efect of copper acetate on the combustion characteristics of anthracite depending on the fractional composition of fuel and additive introduction method.Anthracite was impregnated with 5 wt%of Cu(CH_(3)COO)_(2)by mechanical mixing and incipient wetness impregnation.Four anthracite samples of diferent fraction with d<0.1 mm,d=0.1-0.5 mm,d=0.5-1.0 mm,and d=1.0-2.0 mm were compared.According to EDX mapping,incipient wetness impregnation provides a higher dispersion of the additive and its uniform distribution in the sample.The ignition and combustion characteristics of the modifed anthracite samples were studied by thermal analysis and high-speed video recording of the processes in a combustion chamber(at heating medium temperature of 800℃).It was found that copper acetate increases anthracite reactivity,which was evidenced by decreased onset temperature of combustion(ΔT_(i))by 35-190℃and reduced ignition delay time(Δτ_(i))by 2.1-5.4 s.Copper acetate reduces fuel underburning(on average by 70%)in the ash residue of anthracite and decreases the amount of CO and NO_(x)in gas-phase products(on average by 18.5%and 20.8%,respectively).The mechanism for activation of anthracite combustion by copper acetate is proposed.

叠氮化铅驱动飞片起爆下级装药的试验研究

为了研究叠氮化铅驱动飞片的影响因素,采用钢凹法、锰铜压阻测爆压法研究了序列的发火能量、起爆药药量、隔爆元件的材料和厚度、点火药药量对序列传爆、隔爆能力的影响。结果表明:序列需同时满足最低发火能量和起爆药药量条件才能正常传爆,起爆所需的最低发火能量为3.4 mJ,叠氮化铅最小装药量4.7 mg;隔爆元件镍、硅材料的厚度在0.32~0.80 mm时,导爆药不发生爆轰反应,但产生了凹坑和烧蚀现象;点火药高度在0.25~1.25 mm时,起爆元件的爆压变化不显著。

纳米硼对Al/CuFe_(2)O_(4)@NC复合物点火和燃烧反应特性的影响

为实现纳米铝热剂复合物反应活性的调节,采用静电喷雾技术制备了一系列不同Al/B摩尔比的Al/B/CuFe_(2)O_(4)@NC复合物,并通过XRD、FT-IR、SEM、DSC、激光点火和燃烧实验对复合物的相组成、结构和铝热反应特性进行系统表征分析。DSC结果表明,纳米B有益于增加复合物的热释放能和提高其热稳定性,Al/B摩尔比为5/5工况下的热释放能由1138.5增至1426.9J/g,铝热反应温度随B含量的增加而提高。点火和燃烧实验发现,静电喷雾能显著增强复合物的反应活性,使其点火延迟由16ms降至10ms,燃速由3.34增至6.01cm/s;通过改变Al/B摩尔比,复合物的燃速、燃烧室压力增速和静电火花感度分别在6.01~36.36cm/s、0.05~0.17MPa/ms和61.25~11.25mJ之间可调,而当Al/B摩尔比小于5/5时,其点火和燃烧困难,表明B粉是调节复合物活性的有效添加剂。

改性双基推进剂粉末自着火行为实验研究

为降低推进剂意外着火带来的危害,需要对典型改性双基推进剂的自着火行为及热安全性开展研究。使用快速压缩机实验平台,结合高速成像及动态压力采集技术,发展并验证了超快热刺激方法,开展了改性双基推进剂在快速热加载环境(加热速率大于104K/s)下的响应实验,获得了含环三亚甲基三硝胺(RDX)改性双基推进剂典型自着火行为,以及含环四亚甲基四硝胺(HMX)和1,1-二氨基2,2-二硝基乙烯(FOX-7)改性双基推进剂的着火临界条件。结果表明:在1.0 MPa、901.2 K时,含HMX改性双基推进剂未发生着火,而压力升高至3.0 MPa,推进剂样品发生明显的着火现象;对于含HMX和FOX-7改性双基推进剂,其着火临界温度均随压力的增加而降低;在相同压力下,含FOX-7改性双基推进剂的临界着火温度低于含HMX改性双基推进剂的临界着火温度。