摘要
为探索高致密球形黑索今(H‑RDX)与普通黑索今(RDX)对浇注炸药性能的影响,采用扫描电子显微镜(SEM)、差示扫描量热仪(DSC)等对两者的晶体形貌、热稳定性及机械感度进行评估;同时以典型浇注配方为例,探讨RDX类别对药浆黏度、药柱密度、爆速和冲击波感度的影响规律。结果表明:H‑RDX表面光滑,晶体缺陷少,球形度高;与普通RDX相比,H⁃RDX的热分解表观活化能Ea和活化焓ΔH分别高10.79 kJ·mo
图文摘要
The thermal stability of both ordinary RDX and high density spherical RDX were analyzed by DSC. The mechanical sensitivity of both ordinary RDX and high density spherical RDX were tested. The cast explosives were prepared by ordinary RDX and high density spherical RDX, and its slurry viscosity, density, detonation velocity and shockwave sensitivity were tested.
关键词
黑索今(RDX)作为一种传统的单质炸药,爆炸性能良好且成本相对较低,广泛应用于推进剂、发射药和混合炸药中,是当前和未来一段时间内炸药及固体推进剂装药的主要品
炸药颗粒的晶体粒度,晶体形貌、缺陷等因素对塑料粘结炸药的性能有直接影
本研究分别采用高致密球形RDX、普通RDX进行级配浇注,通过对两种RDX热稳定性,机械感度、药浆黏度、药柱密度、爆速及冲击波感度的研究,分析RDX晶体形貌的变化对浇注炸药性能的影响,以期为高致密球形RDX在浇注炸药中的推广应用提供借鉴。
材料:Ι型1类RDX、超细RDX(20~40 μm),工业纯,江苏红光化工有限公司;高致密球形RDX(10~12目、100~120目),工业纯,中国兵器工业集团第375厂;石墨,d50≤5 μm,工业纯,青岛日升石墨有限公司;铝粉,(40±4) μm,工业纯,明宇铝业有限公司;端羟基聚丁二烯(HTPB),羟值0.74 mmol·
仪器:DSC1型差式扫描量热仪,梅特勒⁃托利多公司;Quanta 200FEG环境扫描电子显微镜,荷兰FEI公司;S⁃4800型扫描电子显微镜,日立公司。
浇注方法:采用“配药⁃捏合⁃浇注⁃固化
浇注级配质量比:含高致密球形RDX的浇注炸药配方中高致密球形RDX大小球级配比为3∶1;含普通RDX的浇注炸药配方中Ι型1类RDX与超细RDX级配比为1.68∶1。
固化条件:固化温度(60±2) ℃,固化时间6天。
药柱规格:Ф 40 mm × 40 mm。
使用扫描电子显微镜对Ι型1类普通RDX和高致密球形RDX进行形貌表征;采用差示扫描量热仪,以5,10,15,20 K∙mi
通过SEM定性分析普通RDX(Ι型1类RDX)与高致密球形RDX晶体颗粒的表观形貌,二者SEM照片见

a. ordinary RDX

b. high density spherical RDX
图1 普通RDX与高致密球形RDX形貌SEM图
Fig.1 SEM images of ordinary RDX and high density spherical RDX(H‑RDX)

a. ordinary RDX

b. high density spherical RDX
图2 普通RDX与高致密球形RDX在不同升温速率下的DSC曲线
Fig.2 DSC curves of ordinary RDX and high density spherical RDX at different heating rates
根据Kissinger公式(1
(1) |
(2) |
式中,β为升温速率,K∙mi
A is the pre⁃exponential factor. Ea is the apparent activation energy. Tp0 is the peak temperature when β is zero. ΔH is the enthalpy of activation. ΔS is the entropy of activation. ΔG is the free energy of activation. Te is the isokinetic temperature.
利用公式(3
(3) |
式中,Tp0为升温速率趋近于0时的热分解峰温,K;b、c为常数。
利用以上计算结果,根据公式(4)、(5)、(6
(4) |
(5) |
(6) |
式中,ΔH为反应活化焓,kJ∙mo
普通RDX与高致密球形RDX的反应速率常数k可体现其热分解速率,当二者反应速率常数k相同时,所对应温度为等动力学点温度Te,该温度可用Arrhenius公式(7)求得,计算结果见
(7) |
式中,T为特征温度,K;A、R、Ea的含义同式(1)。
从热力学角度来讲,高致密球形RDX与普通RDX的ΔG均大于0,且高致密球形RDX的ΔH比普通RDX高出10.81 kJ·mo
普通RDX及高致密球形RDX的机械感度测试结果见
H50 is the value of characteristic drop height.
这是由于高致密球形RDX表面光滑,棱角较少,附着小晶体颗粒少,在受到机械作用时,晶体与外部加载物,晶体与晶体间产生更少热量;高致密球形RDX缺陷较少,形貌相对规则呈类球形,更有利于热量的散发。受到机械作用时,高致密球形RDX较普通RDX而言,产热少散热多,根据热点理论,其机械感度更低。
不同配方药浆黏度及药柱密度测试结果见
由
这是由于高致密球形RDX表面光滑,球形度高,使其药浆黏度更低,流散性更好,浇注时药浆能更均匀密实地流平,不会引入气孔;同时,不同粒径的球形RDX颗粒之间可以更密实地填充,导致高致密球形RDX药柱密度更大。由于铝粉密度高于RDX密度,导致

图3 普通RDX与高致密球形RDX浇注药柱表观形貌图
Fig. 3 Photographs of ordinary RDX⁃based and high density spherical RDX⁃based cast explosives cylinders
不同配方药柱的爆速见
为减少试验量,以药柱未发生爆轰时的最小隔板块数来近似表示药柱的冲击波感度,结果见
plate is organic glass with 2 mm thickness.
由
(1)高致密球形RDX热分解表观活化能Ea与活化焓ΔH分别比普通RDX高出10.79 kJ·mo
(2)相同配方下高致密球形RDX药浆黏度更低,药柱密度更高且更加密实,爆速更高且高致密球形RDX优良的工艺性能使其能达到更高水平的爆速(8000 m·
(3)相同配方下高致密球形RDX浇注药柱冲击波感度更低,分别比普通RDX低10%(含铝配方中)和14%(不含铝配方中)。
(责编: 姜 梅)
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