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目录 contents

    摘要

    为探究铝/聚四氟乙烯(Al/PTFE)活性材料在动态载荷下的力学行为及其点火机理,采用分离式霍普金森压杆对不同成型压力下所制备的Al/PTFE试件进行动态压缩试验。试验结果显示,当应变率为2960~5150 s-1时,Al/PTFE试件在动态加载下呈现出典型的弹塑性力学行为,成型压力为50~150 MPa时,Al/PTFE试件的屈服强度和硬化模量并未表现出应变率效应。成型压力30~80 MPa时,Al/PTFE试件的速度点火阈值随成型压力的增加从28.77 m·s-1缓慢升高到29.22 m·s-1,材料的点火延迟时间始终保持在600~700 μs。当成型压力达100 MPa时,Al/PTFE试件的速度点火阈值大幅下降至26.60 m·s-1,且随着撞击速度的提高,活性材料的点火延迟时间由1000~1100 μs降到600~700 μs。结合扫描电镜结果可知,成型压力为100~150 MPa时,活性材料内部的局部大尺寸孔洞是材料速度点火阈值下降的重要因素。Al/PTFE活性材料的撞击引发点火特性主要与外部载荷和内部微观形貌有关。

    Abstract

    In order to investigate the dynamic behavior and ignition mechanism of Al/polytetrafluoroethylene(PTFE) reactive material under dynamic loading, a Split Hopkinson Pressure Bar (SHPB) was used to conduct the dynamic compression experiment on reactive materials with different molding pressure. Experimental results show that the Al/PTFE reactive material exhibits typical elastic‑plastic mechanical behavior under dynamic loading at strain rate ranging from 2960 s-1 to 5150 s-1. The yield strength and hardening modulus of Al/PTFE reactive materials do not show strain rate effect when the molding pressure is 50-150 MPa. The velocity ignition threshold increases slowly from 28.77 m·s-1 to 29.22 m·s-1 with the molding pressure. When the molding pressure increases to 100 MPa, the velocity ignition threshold drops significantly to 26.60 m·s-1. With the increase of the impact velocity, the ignition delay time for reactive materials with the molding pressure of 100-150 MPa decreases from 1000-1100 μs to 600-700 μs, while that of reactive materials with the molding pressure of 30-80 MPa maintains at 600-700 μs. Combining with results of Scanning Electron Microscopy, it is found that the local larger pores inside the reactive materials with higher molding pressure is the main factor for the sudden drop of the velocity ignition threshold. Therefore, the impact ignition characteristics of Al/PTFE reactive materials are mainly related to the external loading form and the internal micro‑morphology.

    Graphic Abstract

    图文摘要

    The dynamic behavior and ignition mechanism of Al/PTFE reactive material with different molding pressure were investigated based on SHPB, and the effect of external loading form and the internal micro‑morphology was discussed.

  • 1 引 言

    活性材料又可称为反应材料或多功能含能结构材料,该材料通常由两种或多种非爆炸固体组成,具有一定的强度、硬度和质量密度。不同于传统的钢、钨合金等金属破片依靠单一的动能来打击目标,利用活性材料制成的反应破片在高速撞击穿透目标的同时会迅速产生燃烧或爆炸效应,释放大量的化学能对目标造成更大的毁伤。

    活性材料凭借其广阔的应用前景吸引了国内外众多学者的关[1,2,3,4,5]。要实现活性材料在应用技术上的突破,就要明确材料在不同载荷条件下的反应机理。Ames[6]和Mock[7,8]设计了直接撞击、间接撞击、两步撞击等多类型的冲击加载试验对铝/聚四氟乙烯(Al/PTFE)活性材料的冲击反应行为及引发机理进行了深入研究,高速摄影图像显示试件点火首先出现在强剪切变形区,在该区域会产生高温和高压效应。但基于一维冲击波加载对比试验证实该能量并不足以使Al/PTFE材料产生点火效应,他们推测材料冲击引发很可能与裂纹扩展特性、断裂表面能和孔洞塌陷有关。冯彬[9,10,11]研究了不同铝含量Al/PTFE活性材料在准静态压缩下的反应性能,结果显示压缩反应后的试件截面上可以观察到张开型裂纹和剪切裂纹,作者推测准活性材料的静态发火与裂纹的形成有直接关系。

    学者们基于分离式霍普金森压杆(SHPB)装置对活性材料的撞击点火开展了广泛的研究。任会兰[12,13]通过试验发现,Al/W/PTFE材料在入射杆撞击下会发生剧烈的化学反应,随着W颗粒含量的增加,材料的反应活性和反应持续时间也会逐渐下降。对于W/Zr活性材料,SHPB撞击试验表明破碎是该类金属间化合物活性材料发生反应的前提,破碎程度直接决定了材料反应的体现形式,他们推测脆性材料的裂尖温升是反应的点火因[14,15]。Herbold[16]对不同颗粒尺寸Al/W/PTFE活性材料的动态力学行为进行测试,认为W颗粒的加入可以导致材料各组分内能在撞击过程中的再分布,使得较轻软的Al和PTFE获得更多的热量,推测这对活性材料的撞击引发至关重要。

    现有关于活性材料的研究主要集中在材料的配方、制备工艺、力学性能、能量释放以及应用等方面,而关于材料点火机理的研究较少,虽然已有发表工作推测活性材料的点火与材料的变形、断裂和破坏等因素相关,但未给出其明确的作用规律。为此,本研究通过分离式霍普金森压杆(SHPB)对不同成型压力所制备的Al/PTFE活性材料进行撞击引发试验,以探究成型压力对活性材料力学性能、速度点火阈值和点火延迟时间的作用规律,结合活性材料的微观形貌,探究了活性材料在动态载荷下的点火机理。

  • 2 实验部分

  • 2.1 材料制备

    基于模压烧结法制备Al/PTFE活性材料,制备流程如图1[12]。首先根据活性材料的主反应方程式4Al+3C2F4=4AlF3+6C称量粉体,其中Al和PTFE粉末的质量比为26.5∶73.5,粉末粒径分别为10 μm和15 μm。通过V型混粉机和电热恒温箱将称量好的粉体充分混合并干燥,其中混粉时间8 h,恒温箱温度55 ℃。采用万能试验机将活性粉体模压成型,通过控制成型压力(30~150 MPa)获得不同孔隙率的材料胚体,试件的设计尺寸为ϕ10 mm×5 mm。

    图1
                            Al/PTFE活性材料制备流程图[12]

    图1 Al/PTFE活性材料制备流程[12]

    Fig.1 Preparation process[12]

    将压制成型的胚体置于烧结炉中进行无压烧结,烧结气氛为氩气,炉膛气压0.2 MPa。烧结曲线如图2所示,由于PTFE烧结过程是一个相变过程,当温度超过327 ℃时,大分子结构中的晶体部分转变为无定形结构,结晶区域即完全消失;而当温度低于此温度时又会复结晶,且冷却速度越慢结晶度越大。为了保证所烧试件的力学性能,设置炉体在降温过程中于327 ℃处保温1 h。Al/PTFE活性材料的参数如表1所示,材料的体积孔隙率ϕ0=1-VS0/V0,其中VS0为试件内密实材料的体积,V0是试件的表观体积。

    图2
                            烧结曲线

    图2 烧结曲线

    Fig.2 Sintering curve

    表1 不同成型压力Al/PTFE活性材料参数

    Table 1 Parameters of Al/PTFE reactive materials with different molding pressures

    pm / MPaϕ / %ρ / kg·m-3m / g
    304.821830.849
    504.022010.856
    802.922260.865
    1002.422370.870
    1202.222430.872
    1502.122450.873

    NOTE: pmis molding pressure. ϕ is the porosity of specimens. ρ is the density of specimens. m is the mass of specimens.

  • 2.2 动态压缩试验

    采用ϕ14.5 mm分离式霍普金森压杆(SHPB)对不同成型压力活性材料进行动态压缩试验,装置如图3所示。试验过程中,高压气室驱动子弹撞击入射杆,所产生的应力波在入射杆、透射杆以及试件中传播。通过入射杆和透射杆上应变片所采集到的应变‑时间信号,可以获得试件上的应力和应变的信息。

    图3
                            SHPB装置示意图

    图3 SHPB装置示意图

    Fig.3 Schematic diagram of SHPB device

  • 3 结果与讨论

  • 3.1 动态力学行为

    由于Al/PTFE活性材料的波阻抗较低,为获取清晰明确的透射波信号,在活性材料的动态力学行为测试试验中采用铝杆对其进行动态加载。所采用的入射杆和透射杆均为1500 mm,杆直径为14.5 mm,子弹长度为300 mm,试件尺寸为ϕ10 mm×5 mm。试验过程中采用波形整形器对入射脉冲进行波形整形以减缓入射波上升沿,通过粘贴于入射杆和透射杆上的应变片采集脉冲信号,如图4所示。

    图4
                            应力波在SHPB装置中的传播情况

    图4 应力波在SHPB装置中的传播情况

    Fig.4 Propagation of stress wave in SHPB device

    对不同成型压力所制备的Al/PTFE活性材料进行不同应变率下的动态压缩试验,所获得的动态应力‑应变曲线如图5所示。由图5可知,Al/PTFE试件在动态压缩下的应力‑应变曲线可分为弹性阶段和塑性硬化阶段。弹性阶段内提供主要变形的是PTFE基体,此时无论是PTFE基体还是Al颗粒都只发生了弹性变形。随着载荷增加,材料进入塑性硬化阶段。PTFE基体发生急剧变形,试件内的孔洞被逐步压缩,Al颗粒相互挤压接触从而形成力链,使得试件可以承载更高的应力。加载达到峰值载荷时,基体和颗粒发生脱粘,试件内部微裂纹扩展、汇合,进而形成宏观裂纹,致使试件发生整体失效。

    html/hncl/CJEM2019024/alternativeImage/5d725ef9-3c07-4ed8-8403-39a889344159-F013.png

    a. pm=150 MPa

    html/hncl/CJEM2019024/alternativeImage/5d725ef9-3c07-4ed8-8403-39a889344159-F014.png

    b. pm=120 MPa

    html/hncl/CJEM2019024/alternativeImage/5d725ef9-3c07-4ed8-8403-39a889344159-F015.png

    c. pm=100 MPa

    html/hncl/CJEM2019024/alternativeImage/5d725ef9-3c07-4ed8-8403-39a889344159-F016.png

    d. pm=80 MPa

    html/hncl/CJEM2019024/alternativeImage/5d725ef9-3c07-4ed8-8403-39a889344159-F017.png

    e. pm=50 MPa

    html/hncl/CJEM2019024/alternativeImage/5d725ef9-3c07-4ed8-8403-39a889344159-F018.png

    f. pm=3 0MPa

    图5 不同成型压力所制备活性材料的动态力学行为

    Fig.5 Dynamic mechanical behavior of reactive materials with different molding pressures

    图5中的应力‑应变曲线获得的Al/PTFE活性材料的动态力学性能数据,见表2。由表2可知,随应变率的提高,Al/PTFE活性材料的破坏应变和强度极限增加。成型压力为50~150 MPa时,活性材料的屈服强度和硬化模量波动较小,未表现出应变率效应。然而,当成型压力为30 MPa时,由于试件内部的颗粒和基体结合得不够紧密且孔洞数量较多,材料在动态载荷的作用下可以被进一步压实,进而导致活性材料的硬化模量随应变率的提高而增加。

    表2 不同成型压力Al/PTFE活性材料动态力学性能数据

    Table 2 Dynamic properties data of Al/PTFE reactive materials with different molding pressures

    pm / MPaV0 / m·s-1ε˙ / s-1Eh / MPaσm/ MPaεf
    15018.942960158.3069.140.29
    22.213500158.3191.370.43
    26.164270165.51110.230.52
    29.244850170.61127.200.60
    12018.732980165.5470.730.28
    22.663620168.2794.620.47
    26.574330174.34119.740.52
    29.905030167.62132.370.63
    10019.123040155.0976.700.32
    22.493560158.7391.060.45
    26.304270169.67108.630.52
    29.784820154.01122.390.65
    8018.883000141.8169.510.30
    23.043600146.2989.110.46
    26.724290167.60110.410.52
    29.434950157.60124.730.61
    5018.152950107.2065.530.35
    22.773650152.4788.820.45
    26.584290165.75108.130.53
    29.745050156.81126.060.64
    3018.27293097.6061.990.34
    22.023500113.7076.960.48
    26.824300158.35107.100.50
    30.145150179.60135.230.54

    NOTE: pm is molding pressure. V0 is the Initial velocity of striker bar. ε˙ is the strain rate of specimens. Eh is the hardening modulus of specimens. σm is the ultimate strength of specimens. εf is the failure strain of specimens

  • 3.2 撞击点火特性

    由于铝杆的强度和波阻抗均较低,难以在SHPB装置的速度区间内激发活性材料发生反应。采用钢制子弹、入射杆以及透射杆对活性材料进行撞击点火测试,以探究其撞击点火特性。入射杆和透射杆的长度均为1200 mm,子弹长度为300 mm。试验中由激光测速仪获得子弹的撞击速度,通过高速摄影装置记录Al/PTFE试件的变形、破坏直至撞击点火的整个过程,高速摄影设置帧率为20000 fps。结果见图6

    图6
                            Al/PTFE活性材料的撞击点火过程(成型压力:100 MPa,撞击速度:27.66 m·s-1)

    图6 Al/PTFE活性材料的撞击点火过程(成型压力:100 MPa,撞击速度:27.66 m·s-1)

    Fig.6 Impact ignition process of Al/PTFE reactive material (molding pressure: 100 MPa, impact velocity: 27.66 m·s-1)

    图6可知,Al/PTFE试件在0~100 μs内发生压缩变形;150 μs时试件已经发生破坏且有部分试件已经被挤压出压杆边缘;1050 μs时试件发生撞击点火反应,产生明亮的火光并伴有强烈的爆鸣声,反应持续时间在1500 μs以上。高速摄影结果显示Al/PTFE试件在应力波的作用下首先发生整体变形,可以通过粘贴于入射杆和透射杆上的应变片获得初始加载下试件内的应力和变形情况。然而,之后Al/PTFE试件发生破碎、向外飞散,试件已脱离初始加载时的一维应力均匀状态,因此无法通过常规的数据处理方法获得破坏后Al/PTFE试件的应力内状况。文献[17]提供一个简单的方法,通过采集到的入射波和反射波信号,初步估算了试件与入射杆接触面的应力随时间的变化情况,该结果与锰铜计所测得的应力信号符合良好。结合文献[18]对多次应力脉冲加载下试件应力信息的测试方法,本研究通过透射杆上应变片所采集到的信号获得了试件与透射杆接触面的应力信息。尽管该应力信息不是Al/PTFE试件内的真实受力情况,却可以定性分析外部撞击载荷与活性材料点火行为之间的关系。

    分别将3.1节中铝杆动态力学行为测试试验和本节钢杆撞击点火试验后的试件进行收集。以成型压力为80 MPa的试件为例作对比分析,如图7所示。其中,1#试件为实验前成型压力80 MPa的Al/PTFE活性材料试件形貌,2#3#试件分别为铝杆动态力学行为测试试验和钢杆撞击点火试验后的试件图像。

    图7
                            动态压缩试验后的Al/PTFE试件

    图7 动态压缩试验后的Al/PTFE试件

    Fig.7 Al/PTFE specimens after dynamic compression

    图7可知,3#试件在试验中发生了剧烈化学反应。2#试件在动态载荷作用下发生了大幅轴向和径向变形,呈现出了良好的延展性,Al/PTFE试件的径向远端在拉应力的作用下有局部断裂现象存在。3#试件表面附着有材料撞击点火后的反应产物,呈现出明亮的金属光泽。

    采用“升降法[19]获取Al/PTFE试件的速度点火阈值,即若试件发生反应则降低子弹的撞击速度,反之则提高子弹的撞击速度,最后获得可以使材料发生反应的临界点火速度,用SHPB试验中子弹(ϕ14.5 mm×300 mm,0.39 kg)的撞击速度表示。结果如图8所示,成型压力为30~80 MPa时,随成型压力的增加或孔隙率的降低,Al/PTFE试件的速度点火阈值小幅提高,这与传统非均质含能材料的变化特点相似,即材料内的热点温度和数量均随孔隙率的降低而减小,从而提高了点火阈[20]。成型压力增加到100 MPa时,Al/PTFE活性材料的点火阈值发生了较大幅度的下降(由80 MPa时的29.22 m·s-1下降到了100 MPa时的26.60 m·s-1)。从图5c和图5d的结果可知,相同外部载荷条件下,该两组成型压力活性材料的动态力学行为并未发生明显改变。分析认为,当成型压力强100 MPa时,Al/PTFE的撞击点火的速度阈值的下降可能与试件的孔隙率或细微观结构有关。

    图8
                            Al/PTFE活性材料点火阈值

    图8 Al/PTFE活性材料点火阈值

    Fig.8 Ignition threshold of Al/PTFE reactive materials

    图9为Al/PTFE活性材料的点火延迟时间随成型压力和撞击速度的变化规律,其中点火延迟时间定义为高速摄影结果中第一次压缩脉冲抵达试件端面至点火现象出现的时间间隔。图9表明,Al/PTFE试件的点火延迟时间主要集中在600~700 μs和1000~1100 μs内。成型压力较高(100~150 MPa)时,Al/PTFE试件能够在1000~1100 μs时间区间内发生点火,且随子弹撞击速度的提高,试件的点火延迟时间可以提高到600~700 μs内。对于成型压力30~80 MPa的Al/PTFE试件,子弹的撞击速度从27.76 m·s-1提高到31.97 m·s-1,材料只能在600~700 μs内发生点火现象。因此,进一步推测Al/PTFE活性材料的某些力学行为或细微观结构可能在成型压力达100 MPa时发生显著改变,进而影响了Al/PTFE活性材料的点火行为。

    图9
                            Al/PTFE活性材料的点火延迟时间

    图9 Al/PTFE活性材料的点火延迟时间

    Fig.9 Ignition delay time of Al/PTFE reactive materials

    成型压力分别为80 MPa和100 MPa时,Al/PTFE试件在不同撞击速度下与透射杆接触面的应力如图10所示。图10a表明,应力波对Al/PTFE试件进行了三次脉冲加载,第一至第三次应力幅值依次增大。从高速摄影观察到,第一个脉冲内试件发生均匀变形,此阶段内的应力‑时间曲线主要体现了材料从初始加载到失效的动态力学行为。第二次和第三次应力脉冲的作用时间与试件的两个点火延迟时间区间相对应。对于成型压力为100 MPa的Al/PTFE试件,子弹撞击速度为26.6 m·s-1时,第三次应力脉冲的峰值约为280 MPa,Al/PTFE试件发生了撞击点火,点火延迟时间为1100 μs。当撞击速度提高到28.97 m·s-1时,第二次应力脉冲峰值约为263 MPa,点火延迟时间提前到了650 μs。图10b中,成型压力80 MPa时,当子弹撞击速度高达28.26 m·s-1,第三次应力脉冲幅值可达443 MPa时,Al/PTFE试件仍未能发生反应。子弹撞击速度提高到29.22 m·s-1,第二次应力脉冲幅值增加到245 MPa时,Al/PTFE才能够在650 μs时发生点火。通过分析两组成型压力(80,100 MPa)Al/PTFE点火特性,可以认为Al/PTFE的撞击点火反应不仅与加载脉冲的应力幅值相关,还与Al/PTFE本身的细微观结构有关。

    html/hncl/CJEM2019024/alternativeImage/5d725ef9-3c07-4ed8-8403-39a889344159-F008.png

    a. pm=100 MPa

    html/hncl/CJEM2019024/alternativeImage/5d725ef9-3c07-4ed8-8403-39a889344159-F009.png

    b. pm=80 MPa

    图10 Al/PTFE试件与透射杆接触面的应力情况

    Fig.10 Stress on the interface between Al/PTFE specimen and transmission bar

  • 3.3 撞击点火机理

    采用扫描电子显微镜对不同成型压力下Al/PTFE活性材料的细微观形貌进行观察。结果如图11所示,由图11可知,Al/PTFE活性材料中白色的Al颗粒广泛分布于灰色的PTFE基体中,基体以及基体与Al颗粒界面处存在大量的微孔洞。当成型压力为30~80 MPa时,虽然其计算所得的体积孔隙率较高(表1),但是试件内孔洞分布较为均匀,孔洞的尺寸也较小,孔径约为6~8 μm。当成型压力为100~150 MPa时,活性材料的整体孔隙率较低,试件内大部分区域呈现出与低成型压力时相似的微观形貌,但是材料内孔洞分布的不均匀性提高,试件中有局部较大尺寸的孔洞存在,其孔径约为14~16 μm。

    图11
                            Al/PTFE活性材料扫描电镜结果

    图11 Al/PTFE活性材料扫描电镜结果

    Fig.11 Scanning electron microscope results of Al/PTFE reactive materials

    图11显示,当成型压力较高时(100~150 MPa),试件内有局部大尺寸孔洞存在。该现象可能是由多种因素共同作用而成。首先,作为基体材料,PTFE粉末具有极高的结晶度,当成型压力超过再结晶所需压力时,粉末颗粒会产生冷拉伸,而在烧结过程中胚体内部具有恢复粉体颗粒原来形状的倾向,导致材料内部微损伤的产[21]。另外,当压制力较高时,试件内部有可能捕捉更多的空气,其在烧结过程中又不易释放,也会在试件内形成较大尺寸的空隙。同时,高成型压力下,试件内部会有大量残余应力,该残余应力在无压烧结过程中的释放,以及Al颗粒与PTFE基体间热导率及热膨胀系数的差异,均会导致烧结后的试件局部出现较大尺寸的微损伤。

    活性材料内部的初始孔洞尺寸对其撞击点火现象影响显著。多次脉冲加载引发含能材料发生反应的潜在热点机理有孔洞的产生和再压缩,裂纹的产生和汇聚及摩擦,塑性功以及剪切带的产生[22,23]。成型压力较高时,Al/PTFE活性材料局部存在较大尺寸孔洞(图11),当撞击速度达到点火阈值时,试件内的局部较大尺寸孔洞在三次应力脉冲压缩下,可以产生大幅的粘塑性变形,粘塑性功在活性材料局部能够产生可观温[20,24],进而引发试件发生反应。另外,初始尺寸较大的微损伤处易于发生微裂纹的萌生和扩展,裂纹扩展过程中能量的释放和裂纹面的摩擦均有助于热点形 [23,25]。因此,高成型压力活性材料能够在较低速度撞击下,于第三个应力脉冲处发生点火反应,点火时间为1000~1100 μs。随着撞击速度的提高,活性材料内部的损伤敏化程度加剧,微损伤在高幅值的外部载荷下能够产生更高的热点温升,使得试件能够在第二个应力脉冲作用下就可以发生点火,试件的点火时间提前到600~700 μs。成型压力30~80 MPa时,图11显示Al/PTFE活性材内部微孔洞尺寸较小,当撞击速度较小时,微损伤的演化受限,难以在第三个脉冲处产生点火所需温升。通过提高撞击速度的方式,可以使微损伤在第二个应力脉冲处就达到点火温度,进而引发活性材料发生反应。因此低成型压力活性材料的点火时间始终保持在600~700 μs内,且具有较高的点火阈值。

  • 4 结 论

    (1) 采用模压烧结法在不同成型压力下制备了Al/PTFE活性材料,基于霍普金森压杆(SHPB)装置对活性材料的动态力学性能进行测试。结果表明,当应变率为2960~5150 s-1时,活性材料在动态载荷下呈现出典型的弹塑性力学行为;成型压力为30 MPa时,随着应变率增加,Al/PTFE材料的硬化模量增加;成型压力为50~150 MPa时Al/PTFE的屈服强度和硬化模量并未表现出应变率效应。

    (2) 采用升降法,分析了Al/PTFE活性材料的撞击点火阈值和点火延迟时间随成型压力和载荷的变化规律;成型压力30~80 MPa时,活性材料的速度点火阈值呈现出传统非均匀含能材料相似的特点,即随着材料内孔隙率的降低,点火阈值增加,其点火延迟时间始终在600~700 μs;成型压力加到达100 MPa时,Al/PTFE活性材料的速度点火阈值出现了大幅下降,随着子弹撞击速度的提高,材料的点火延迟时间可以从1000~1100 μs提前到了600~700 μs。

    (3) 撞击载荷下,Al/PTFE试件内的孔隙率和微细观结构主导了其撞击反应特性。成型压力超过100 MPa时,试件内局部会出现较大尺寸的微孔洞,微孔洞可以在多次脉冲载荷下产生可观的局部温升,并且有助于加剧活性材料在前两次应力脉冲作用下的损伤敏化,从而降低了成型压力100~150 MPa活性材料的点火阈值。

    (责编: 张 琪)

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李尉

机 构:北京理工大学 爆炸科学与技术国家重点实验室, 北京 100081

Affiliation:State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China

邮 箱:wesley@bit.edu.cn

作者简介:李尉(1993-),男,博士,主要从事材料冲击动力学研究。e‑mail:wesley@bit.edu.cn

任会兰

机 构:北京理工大学 爆炸科学与技术国家重点实验室, 北京 100081

Affiliation:State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China

角 色:通讯作者

Role:Corresponding author

邮 箱:huilanren@bit.edu.cn

作者简介:任会兰(1973-),女,博士,教授,主要从事材料冲击动力学研究。e‑mail:huilanren@bit.edu.cn

宁建国

机 构:北京理工大学 爆炸科学与技术国家重点实验室, 北京 100081

Affiliation:State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China

刘元斌

机 构:北京理工大学 爆炸科学与技术国家重点实验室, 北京 100081

Affiliation:State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China

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pm / MPaϕ / %ρ / kg·m-3m / g
304.821830.849
504.022010.856
802.922260.865
1002.422370.870
1202.222430.872
1502.122450.873
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pm / MPaV0 / m·s-1ε˙ / s-1Eh / MPaσm/ MPaεf
15018.942960158.3069.140.29
22.213500158.3191.370.43
26.164270165.51110.230.52
29.244850170.61127.200.60
12018.732980165.5470.730.28
22.663620168.2794.620.47
26.574330174.34119.740.52
29.905030167.62132.370.63
10019.123040155.0976.700.32
22.493560158.7391.060.45
26.304270169.67108.630.52
29.784820154.01122.390.65
8018.883000141.8169.510.30
23.043600146.2989.110.46
26.724290167.60110.410.52
29.434950157.60124.730.61
5018.152950107.2065.530.35
22.773650152.4788.820.45
26.584290165.75108.130.53
29.745050156.81126.060.64
3018.27293097.6061.990.34
22.023500113.7076.960.48
26.824300158.35107.100.50
30.145150179.60135.230.54
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图1 Al/PTFE活性材料制备流程[12]

Fig.1 Preparation process[12]

图2 烧结曲线

Fig.2 Sintering curve

表1 不同成型压力Al/PTFE活性材料参数

Table 1 Parameters of Al/PTFE reactive materials with different molding pressures

图3 SHPB装置示意图

Fig.3 Schematic diagram of SHPB device

图4 应力波在SHPB装置中的传播情况

Fig.4 Propagation of stress wave in SHPB device

图5 不同成型压力所制备活性材料的动态力学行为 -- a. pm=150 MPa

Fig.5 Dynamic mechanical behavior of reactive materials with different molding pressures -- a. pm=150 MPa

图5 不同成型压力所制备活性材料的动态力学行为 -- b. pm=120 MPa

Fig.5 Dynamic mechanical behavior of reactive materials with different molding pressures -- b. pm=120 MPa

图5 不同成型压力所制备活性材料的动态力学行为 -- c. pm=100 MPa

Fig.5 Dynamic mechanical behavior of reactive materials with different molding pressures -- c. pm=100 MPa

图5 不同成型压力所制备活性材料的动态力学行为 -- d. pm=80 MPa

Fig.5 Dynamic mechanical behavior of reactive materials with different molding pressures -- d. pm=80 MPa

图5 不同成型压力所制备活性材料的动态力学行为 -- e. pm=50 MPa

Fig.5 Dynamic mechanical behavior of reactive materials with different molding pressures -- e. pm=50 MPa

图5 不同成型压力所制备活性材料的动态力学行为 -- f. pm=3 0MPa

Fig.5 Dynamic mechanical behavior of reactive materials with different molding pressures -- f. pm=3 0MPa

表2 不同成型压力Al/PTFE活性材料动态力学性能数据

Table 2 Dynamic properties data of Al/PTFE reactive materials with different molding pressures

图6 Al/PTFE活性材料的撞击点火过程(成型压力:100 MPa,撞击速度:27.66 m·s-1)

Fig.6 Impact ignition process of Al/PTFE reactive material (molding pressure: 100 MPa, impact velocity: 27.66 m·s-1)

图7 动态压缩试验后的Al/PTFE试件

Fig.7 Al/PTFE specimens after dynamic compression

图8 Al/PTFE活性材料点火阈值

Fig.8 Ignition threshold of Al/PTFE reactive materials

图9 Al/PTFE活性材料的点火延迟时间

Fig.9 Ignition delay time of Al/PTFE reactive materials

图10 Al/PTFE试件与透射杆接触面的应力情况 -- a. pm=100 MPa

Fig.10 Stress on the interface between Al/PTFE specimen and transmission bar -- a. pm=100 MPa

图10 Al/PTFE试件与透射杆接触面的应力情况 -- b. pm=80 MPa

Fig.10 Stress on the interface between Al/PTFE specimen and transmission bar -- b. pm=80 MPa

图11 Al/PTFE活性材料扫描电镜结果

Fig.11 Scanning electron microscope results of Al/PTFE reactive materials

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pmis molding pressure. ϕ is the porosity of specimens. ρ is the density of specimens. m is the mass of specimens.

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pm is molding pressure. V0 is the Initial velocity of striker bar. ε˙ is the strain rate of specimens. Eh is the hardening modulus of specimens. σm is the ultimate strength of specimens. εf is the failure strain of specimens

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