【作者】 程志鹏；

【导师】 李凤生；

【作者基本信息】 南京理工大学 ， 材料学， 2008， 博士

【摘要】 本论文旨在改善复合固体推进剂的燃烧性能,采用微纳米复合技术,通过对AP/HTPB/Al推进剂配方中的微米Al粉(金属燃烧剂)进行改性,制备出了以微米Al粉为核、纳米金属粒子(燃速催化剂)为壳的复合粉末,并考察了表面包覆纳米金属粒子对Al粉在空气中高温氧化反应性能、对高氯酸铵(AP)和丁羟推进剂(AP/HTPB)热分解催化性能以及对AP/HTPB推进剂燃烧催化性能的影响。本研究为进一步提高AP/HTPB推进剂的燃烧和能量特性提供了详实的实验数据和坚实的理论基础,主要内容如下:首先,采用化学镀和原位置换两种方法制备了核壳纳米Ni-B/Al、Cu/Al、Ni/Al和Co/Al复合粉末,并对复合粉末进行了较为全面的表征。结果表明,通过对制备工艺参数的调控,纳米Ni-B、Cu、Ni、Co在Al粉表面均实现了均匀、致密地包覆,其中Co/Al复合粉末中的纳米Co粒子可以具有球形和片状两种形貌。相比化学镀法而言,置换法具有工艺简单、反应迅速、包覆物可定量等优点,可以推广为Al粉表面金属改性包覆的普适性方法。其次,考察了表面包覆纳米金属粒子对Al粉在空气中高温氧化反应过程的作用。以复合粉末的TG增重率和DSC放热量为衡量标准,利用TG/DSC同步热分析研究了复合粉末中Al粉在空气中的高温氧化反应性能,即高温下Al粉受热转化为氧化铝的氧化效率(包括氧化完全程度、氧化速率及氧化放热量)。结果表明:(1)纳米金属/Al复合粉末的高温氧化反应性能较原料Al粉均有不同程度的提高;(2)复合粉末中随着纳米金属层质量分数的增加,其高温氧化反应性能增强;(3)Al粉表层纳米金属粒子的尺寸与形貌对复合粉末的高温氧化反应性能也均有影响,如微米Cu的包覆不能明显改善Al粉的高温氧化反应性能,球形纳米Co包覆的促进效果要明显高于片状纳米Co包覆;(4)当与复合粉末具有相同质量分数的纳米金属粒子简单掺杂于原料Al粉中时,其对Al粉的高温氧化反应性能没有明显的促进作用。在实验数据结果的基础上,提出了原料ASl粉和核壳纳米金属/Al复合粉末的氧化反应机理。第三,对比研究了核壳纳米金属/Al复合粉末与相应的单一纳米金属对AP及其AP/HTPB推进剂热分解的催化性能,根据热分解峰温和表观分解热的变化来衡量其催化效果。结果表明,对AP以及AP/HTPB推进剂的热分解,纳米金属/Al复合粉末均比相应单一的纳米金属具有更好的催化效果,其中催化性能最好的是含有片状纳米Co粒子的Co/Al复合粉末,它使AP以及AP/HTPB的高温分解峰温分别降低了179.9℃和60.5℃。鉴于微米Al粉对纳米金属粒子的承载既能提高Al粉高温下氧化反应性能,又能较好地催化AP以及AP/HTPB推进剂的热分解,为此研究了核壳纳米金属/Al复合粉末对AP/HTPB推进剂燃烧性能的影响。采用靶线法对推进剂的燃速和压力指数分别进行了测定和计算,根据燃速和压力指数的变化,最终考察各种复合粉末对推进剂燃烧性能的催化作用。结果表明,对于AP/HTPB推进剂燃速和压力指数的影响,核壳纳米金属/Al复合粉末起到了很好的催化效果,其中纳米Cu/Al复合粉末在5MPa和10MPa下分别使AP/HTPB推进剂的燃速较空白推进剂样品增加了40.34%和30.06%,并且在5～11 MPa压力范围内,使推进剂压力指数降低了37.23%。更多还原

【Abstract】 In order to improve the combustion performance of composite solid propellant, this dissertation is intended to discuss the modification of micrometer Al powder in the conventional AP/HTPB/Al propellant formula with core-shell nanocomposites. The influence on the oxidation performance of Al powder, thermal decomposition of AP and AP/HTPB propellant, and catalytic performance in combustion of AP/HTPB propellant, were explored. Detailed experimental data and powerful theoretical evidence were obtained for the enhancement of combustibility and energy features for AP/HTPB propellant. The details are described as below:Firstly, the core-shell Ni-B/Al, Cu/Al, Ni/Al and Co/Al nanocomposites were prepared respectively by means of electroless plating and in-situ displacement, and an overall characterization was given for different nanocomposites. The results showed Ni-B, Cu, Ni, Co nanoparticles could be applied to the surface of Al particle in continuous and uniform manner, wherein, the Co particle presented in both spherical and sheet profiles in the Co/Al nanocomposites. Compared with the electroless plating, the displacement has the merits of simple process, fast reaction and quantified coverage, which can be introduced as a practicable and preferred method for modified Al powder coated with metallic nanoparticle.Secondly, the influence on the oxidation performance of Al powder in the core-shell nanocomposites has been investigated and the results show that: (1) the oxidation performance of core-shell nanocomposites has been improved relatively compared with the raw Al powder; (2) As the mass fraction of nanometer metal layer increases, the oxidation performance increases correspondingly;(3) The size and profile of metallic nanoparticles being coated on the surface of Al powder also have an influence on the oxidation performance of composite powder. For instance, the coating of micro-sized Cu particles failed to improve the oxidation performance of Al powder in an obvious manner, spherical Co coating is better than that of sheet Co nanoparticle; (4) For the simple mixture of nano-sized metallic particles with the Al powder, no apparent improvement of oxidation performance can be obtained. Based on the testing results, the oxidation mechanism was put forward for Al powder and the core-shell nanocomposites.Thirdly, a contrastive analysis has been conducted between the core-shell nanocomposites and single metallic nanoparticle in respect of catalytic performance for thermal decomposition of ammonium perchlorate (AP) and AP/HTPB propellant. The results showed the core-shell nanocomposites had a better catalytic effect compared with single metallic nanoparticle, while the sheet-profiled Co/Al nanocomposite was the best choice, which decreased the high temperature decomposition peak of AP and AP/HTPB propellants by 179.9℃and 60.5℃respectively.Finally, a contrastive study was carried out for the effect between the core-shell nanocomposites and single metallic nanoparticle on combustion performance of AP/HTPB propellant. The burning rate was measured with target line method and the pressure index was calculated. The catalytic effect of different catalysts for propellant on combustion performance were explored. The results showed that the core-shell nanocomposites had a better performance than single metallic nanoparticle in respect of the burning rate and pressure index. Cu/Al nanocomposites increased the burning rate by 40.34 % and 30.06 % for AP/HTPB propellant under the pressure of 5 MPa and 10 MPa respectively, and decreased the pressure index by 37.23 % under the pressure of 5-11 MPa.更多还原