多尺度界面可调型Al-RDX含能复合物的制备及其热分解特性

doi:10.12382/bgxb.2022.0618

摘要/Abstract

摘要：

基于氧化剂/燃料一体化设计理念，在对Al颗粒进行表面修饰的基础上，采用声共振和喷雾干燥技术成功制得了多尺度界面可调半嵌入型Al/RDX和全嵌入型Al@RDX复合颗粒。通过扫描电子显微镜(SEM)等技术对复合颗粒的形貌、密度和燃烧热进行表征，并利用热红同步热分析仪(DSC-TG-FT-IR)对其热分解过程及气相产物进行了研究。研究结果表明：与机械混合物相比，复合颗粒密度基本保持不变，但燃烧热分别提升至17.31 kJ/g和18.82 kJ/g. DSC结果表明两种方式均可提高RDX的热分解放热量：铝粉嵌入未改变RDX的气相分解产物种类，但其中HCHO的相对含量有所增加：嵌入铝粉后RDX第一分解阶段均由二维成核增长模型(A2)转变为链断裂模型(L2)：全嵌入型Al@RDX的第二分解阶段则转变为自催化模型(AC)。

关键词: 多尺度Al-RDX复合物, 界面修饰作用, 声共振技术, 喷雾干燥技术, 热分解特性

Abstract:

Based on the integrated design concept of oxidant/metal fuel (Al) in propellants and the surface modification of aluminum particles, the multi-scale interface-tunable semi-embedded Al/RDX and fully-embedded Al@RDX composites were prepared by resonant acoustic mixing and spray drying. The morphology, true density and heat of combustion of the composites were characterized by scanning electron microscopy (SEM) and other techniques, and the thermal decomposition process and its gas products were studied by simultaneous thermal analyzer (DSC-TG-FT-IR). The results showed that compared with the mechanical mixture, the true density of the composites remained basically unchanged, but the heat of combustion of these two composites was higher, which were 17.31 kJ/g and 18.82 kJ/g. The DSC results showed that the heat of thermal decomposition of RDX can be increased by these two ways. Although the embedding of aluminum particles does not change the types of gas-phase products of RDX decomposition, it is more conducive to generate more HCHO. After the embedding of aluminum particles, the first decomposition stage of RDX changed from the random nucleation model (A2) to the random chain scission model (L2), while the second decomposition stage of the fully-embedded Al@RDX composites was transformed into the autocatalytic model (AC).

Key words: multi-scale Al-RDX composites, interface modification, resonant acoustic mixing technology, spray drying technology, thermal decomposition characteristics

许睿轩, 徐家兴, 薛智华, 吕杰尧, 严启龙. 多尺度界面可调型Al-RDX含能复合物的制备及其热分解特性[J]. 兵工学报, 2023, 44(3): 691-701.

XU Ruixuan, XU Jiaxing, XUE Zhihua, LÜ Jieyao, YAN Qilong. Preparation and Thermal Decomposition Properties of Multi-scale Interface-Tunable Al/RDX Energetic Composites[J]. Acta Armamentarii, 2023, 44(3): 691-701.

图/表 12

图1 声共振仪结构示意图

Fig. 1 Schematic diagram of the structure of the resonant acoustic mixing equipment

图2 复合颗粒的SEM、EDS和TEM图

Fig. 2 SEM, EDS and TEM images of the composite particles

表1 样品的密度和燃烧热测试结果

Table1 Results of the true density and heat of combustion of RDX and the composites with different structures

样品	真密度 /(g·cm^-3)	单位质量燃烧热/(kJ·g^-1)
样品	真密度 /(g·cm^-3)	第1次	第2次	第3次	平均值	标准差
RDX	1.82	9.40	9.81	9.47	9.56	0.22
Al+RDX	2.25	16.84	16.44	16.98	16.75	0.28
Al/RDX	2.25	17.30	17.45	17.17	17.31	0.14
Al@RDX	2.26	19.20	18.57	18.69	18.82	0.33

图3 不同颗粒的真密度测试结果和样品燃烧热对比

Fig. 3 Comparison of the true density and the heat of combustion of the composites with different structures

图4 复合颗粒的DSC曲线对比图

Fig. 4 Comparison of DSC curves of different composite particles

表2 RDX、Al+RDX、Al/RDX和Al@RDX复合颗粒热分解过程DSC特征参数

Table 2 DSC characteristic parameters of RDX, Al+RDX, Al/RDX and Al@RDX composites

样品	T_m/°C	T_i/°C	T_p/°C	T_e/°C	W/°C	△H/(J·g^-1)
RDX^[19]	205.1	226.7	248.7	255.7	29.0	1 747.0
RDX^[21]	204.1		242.3			1 812.0
Al+RDX	205.3	227.4	247.7	254.7	24.8	771.2
Al/RDX	189.4	228.4	251.8	278.6	40.0	779.4
Al@RDX	205.3	223.8	243.0	257.4	30.9	775.2

图5 复合颗粒的TG-DTG曲线对比图

Fig. 5 Comparison of TG-DTG curves of different composite particles

表3 RDX、Al+RDX、Al/RDX和Al@RDX复合颗粒的热分解动力学参数

Table 3 Thermal decomposition kinetic parameters of RDX, Al+RDX, Al/RDX and Al@RDX composites

样品	阶段	联合动力学法				Friedman法		Kissinger法
样品	阶段	m	n	E_a(1)	cA/min⁻¹	E_a(2)	r	E_a(3)	Log A	r
RDX^[21]								196.5	13.79	0.998 5
RDX^[22,23,24]		0.021	0.997	159.6±0.7	3.7×10¹⁵	246.2		130.4	11.87	0.995 0
RDX/TAG-Ni^[21]		0.135	0.944	189.4±1.2	1.2×10¹⁷	192.2	0.995 4	186.5	13.18
RDX/TAG-Co^[21]		0.090	0.891	203.6±2.3	2.8×10¹⁸	156.7	0.999 9	195.3	14.02
Al+RDX	1st	0.461	0.631	153.0±0.7	4.5×10¹⁴	151.5	0.998 5	163.0	10.81	0.995 5
Al+RDX	2nd	0.646	1.053	58.2±2.4	5.2×10⁰⁴	16.0	0.995 3	144.7	8.70	0.992 7
Al/RDX	1st	0.347	1.109	152.0±2.3	1.4×10¹⁴	156.1	0.993 7	136.0	7.77	0.998 6
Al/RDX	2nd	0.606	1.076	148.8±2.1	8.4×10¹²	151.2	0.996 0	192.8	12.85	0.980 9
Al@RDX	1st	0.413	1.093	155.0±1.6	8.7×10¹⁴	150.5	0.989 3	137.1	8.22	0.999 9
Al@RDX	2nd	0.890	0.641	31.1±0.3	5.4×10⁰¹	29.4	0.994 4	155.6	9.85	0.999 0

图6 Friedman等转换率法计算的复合颗粒热分解活化能与转化率的关系曲线

Fig. 6 Dependence of activation energy on the conversion rate of composites by the Friedman method

图7 机械混合物Al+RDX、半嵌入型Al/RDX和全嵌入型Al@RDX复合颗粒的热分解气相产物FT-IR图

Fig. 7 FT-IR results of the gas phase decomposition products of Al+RDX, Al/RDX and Al@RDX composites

图8 RDX热分解过程两种路径的竞争机制

Fig. 8 Competitive mechanism of the two paths in the thermal decomposition process of RDX

图9 联合动力学法计算的RDX、Al+RDX、Al/RDX和Al@RDX复合颗粒热分解动力学模型(D2：二维扩散模型；F1：随机成核后一维核生长模型；R2：收缩模型；R3：相界面收缩模型；L2：链断裂模型；A2：随机成核后二维核生长模型；A3：随机成核后二维核生长模型；AC：自催化模型)

Fig. 9 Comparison of the normalized curves for the decomposition kinetic models of RDX、Al+RDX、 Al/RDX and Al@RDX composites obtained by the combined kinetic method (D2, two-dimensional diffusion model; F1, first order reaction, so-called unimolecular decay law, where random nucleation is followed by an instantaneous growth of nuclei; R2, phase boundary controlled reaction (contracting area), R3, phase boundary controlled reaction (contracting volume); L2, random chain scission model; A2 and A3, random two and three dimensional nucleation and nucleus growth models; AC, autocatalytic model.)

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