摘要
为了研究储氢钽粉(HTa)对铝/聚四氟乙烯(Al/PTFE)反应材料的材料密度和能量密度的影响,制备了4种不同HTa含量(5%,10%,20%,30%)的Al/HTa/PTFE和不含HTa的Al/PTFE圆柱体试件,通过霍普金森压杆实验和弹道枪撞靶侵彻实验,对材料的动态力学性能、点火阈值、撞击毁伤与释能特性进行了对比研究。结果表明,Al/PTFE和Al/HTa/PTFE均为弹塑性材料,应力‑应变变化趋势一致。4种Al/HTa/PTFE材料点火阈值分别为4470,5620,5135
图文摘要
The high‑density metal hydride (HTa) was innovatively applied to improve the material density and reaction energy density of Al/PTFE reactive materials, and Al/HTa/PTFE reactive materials were prepared. Based on the split Hopkinson pressure bar (SHPB) experiment and ballistic gun penetrating target experiment, the effects of HTa filler mass fraction on the dynamic mechanical properties, ignition reaction characteristics, and penetration and reaction energy release of Al/PTFE reactive materials were compared and analyzed.
活性材料又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,铝/聚四氟乙烯(Al/PTFE)是其中较为典型的一种。通过简便的模压、烧结等工艺后,活性材料可制备成具有特定形状、力学强度、质量密度的结构件,因此常被制成反应破片、药型罩等毁伤元对目标进行打
相比于传统反应材料,Al/PTFE反应材料虽具有冲击反应的物化性能,但密度和强度等力学性能不
HTa具有较高的密度(15.1 g·c
尽管目前进行了大量的材料填充改性的毁伤实验,但同时兼顾材料密度与能量密度的研究较少。为改善Al/PTFE材料的密度和能量密度,提高Al/PTFE反应弹丸撞击间隔靶的时序毁伤行为。本研究通过填充改性的方式引入HTa,制备了Al/HTa/PTFE反应材料,并开展了实验研究。通过动态力学实验分析材料的动态力学响应,开展了2种冲击速度的弹道枪冲击实验以验证该材料的侵彻与冲击反应释能效果。并讨论了毁伤效应与填料含量、撞击速度和化学特性的关系。
原料:PTFE,平均粒径25 μm,上海三爱富新材料股份有限公司;Al粉,平均粒径1 μm,湖南金天铝业高科技股份有限公司;储氢钽粉(HTa),8 μm,宁夏东方钽业有限公司;无水乙醇(上海国药集团化学试剂有限公司)。
Al/HTa/PTFE反应材料样品制备:将Al和PTFE的质量分数按照化学平衡比(26.5%/73.5%)进行配比,HTa再以4种含量(5%,10%,20%,30%)填充到Al/PTFE材料中,制备得到不同质量分数HTa的Al/HTa/PTFE反应材料
composites | PTFE /% | Al / % | HTa / % | theoretical maximum density / g·c | actual density after sintering / g·c |
---|---|---|---|---|---|
| 73.5 | 26.5 | 0 | 2.31 | 2.28 |
| 69.8 | 25.2 | 5 | 2.42 | 2.37 |
| 66.2 | 23.8 | 10 | 2.53 | 2.46 |
| 58.8 | 21.2 | 20 | 2.79 | 2.71 |
| 51.5 | 18.5 | 30 | 3.10 | 3.02 |
试件的制备:使用电动搅拌器将
使用直径为20 mm的铝材分离式霍普金森压杆(SHPB)实验装置测试材料的动态力学性能和冲击点火特性,依托合肥姜水动态力学实验技术有限公司平台开展实验,装置示意图如
图1 SHPB实验装置示意图
Fig.1 Schematic diagram of SHPB experimental device
弹道枪冲击毁伤实验测试反应弹丸对间隔钢靶的侵彻毁伤行为,实验依托南京理工大学汤山科研实验中心进行。实验装置如
图2 弹道枪冲击实验
Fig.2 Ballistic impact experiments
考虑到氟聚物反应材料的波阻抗较低,选用铝材实验杆进行试验,并在撞击杆和入射杆之间放置橡胶垫片脉冲整形器,以实现入射脉冲缓慢上升,从而最大限度地减少分散效应,实现试件中的动态应力平衡和恒应变率变形。为了便于应力通过试件快速传递并达到恒定应力状
反应弹丸通过弹托安装在12.7 mm口径弹道枪进行冲击靶板毁伤实验,并通过调整发射药质量实现弹丸2种撞靶速度(900、1250 m·
图3
Fig.3 The true stress‑strain curves of
a.
b.
c.
d.
图4 4种类型Al/HTa/PTFE材料的真实应力‑应变曲线
Fig.4 True stress‑strain curves of four types of Al/HTa/PTFE materials
当试件压缩变形时,金属颗粒在PTFE基体中相互连接形成力链并承受和传递载荷,阻止试件进一步变形。颗粒填料的质量分数或粒度改变对动态载荷下试件塑性变形、失效行为和化学反应具有复杂影
a. HTa
b. Al
c. Al‑HTa‑PTFE mixed powers(
图5 原材料和混合粉末的微观结构图
Fig.5 Microstructure of the original materials and mixed powers
采用“升降法
图6 不同HTa含量的Al/HTa/PTFE材料点火阈值
Fig.6 Ignition threshold of Al/HTa/PTFE materials with different contents of HTa
从
对4种Al/HTa/PTFE材料制成的试件(
图7 Al/HTa/PTFE试件内部扫描电镜结果
Fig.7 Scanning electron microscope results inside of Al/HTa/PTFE specimens
图8 Al/HTa/PTFE材料撞击点火过程 (a.
Fig.8 Impact ignition process of Al/HTa/PTFE materials (a.
结合以上分析可知,HTa质量分数的升高导致Al/HTa/PTFE材料的应变率点火阈值先升高后降低,点火延迟时间先降低后升高。
反应材料毁伤元兼具良好的力学性能和高能量密度,弹丸撞击靶板除了动能打击外,强烈的机械撞击诱发化学反应释放大量热量并形成高压,造成动能和化学能耦合毁伤效果。选取
Steel targets | ||||||
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exp No. | fragment mass / g | impact velocity / m· | ||||||
---|---|---|---|---|---|---|---|---|
damage size / mm | deflection / mm | damage area / m | deflection / mm | damage size / mm | deflection / mm | |||
| 3.55 | 824.0 | Φ20.8 | 24 | - | 0 | - | - |
| 3.58 | 1219.6 | Φ20.8 | 16 | 87.4 | 21.85 | - | - |
| 3.85 | 855.3 | Φ21.1 | 20 | - | 8.54 | - | - |
| 3.85 | 1227.6 | Φ16.9 | 14 | 36.5 | 25.42 | - | - |
| 5.25 | 949.6 | Φ16.8 | 14 | 76.9 | 17.31 | - | - |
| 5.17 | 1234.5 | Φ16.8 | 10 | 273.2 | 19.96 | - | 2.4 |
在扩孔方面,低发射速度的
上述实验表明,Al/HTa/PTFE反应材料在高速冲击毁伤时HTa填料可提高侵彻毁伤能力,造成动能侵彻的同时,冲击引发反应产生高温灼烧、破片等可对目标内部造成二次杀伤。
图9 弹丸撞靶反应过程
Fig.9 Reaction processes of projectiles impacting targets
为了准确对比同一撞靶时刻不同类型试件的反应强度(瞬时火焰面积与最大火焰面积之比),采用图像处理技术调整照片灰度、对比度等参数,并使用Matlab处理得到的二值化图像(
图10 Matlab处理的反应弹丸过程二值化图像
Fig.10 Binarized images of the reaction projectile impact process from Matlab
图11 反应弹丸撞击反应的相对火焰强度与反应时间曲线
Fig.11 Curve between relative flame intensity and reaction time for impact reaction of reactive projectiles
针对Al/HTa/PTFE氟聚物基反应材料,分析了不同HTa含量的反应材料在不同动态载荷下的力学性能,与弹道枪不同速度下的冲击毁伤效果,主要结论如下:
(1)当应变率约为3300
(2)相比于Al/PTFE弹丸,Al/HTa/PTFE弹丸在间隔靶之间存在明显的反应区扩大、对靶板造成严重黑色烧灼痕迹和积碳效果。随着发射速度提高,靶板灼烧痕迹增加,第2靶板毁伤效果提升。在1250 m·
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