【作者】 罗宁；

【导师】 李晓杰；

【作者基本信息】 大连理工大学 ， 工程力学， 2011， 博士

【摘要】 自二十世纪九十年代发现碳包覆金属纳米颗粒(Carbon-encapsulated metal nanoparticles, CEMNPs)以来,其已成为继发现富勒烯C60、碳纳米管之后的又一研究热点,再次掀起了碳材料领域的研究热潮。CEMNPs是一种新型的、核壳结构的碳-金属复合纳米材料,核心由球形纳米金属晶构成,外壳主要由多层石墨片层紧密环绕金属纳米晶核有序包裹。由于碳包覆层的保护,有效的防止了金属纳米晶团聚、长大,保护了内核金属纳米晶不发生氧化及环境腐蚀,同时提高了纳米金属活性与生物体之间的相容性。爆轰法以速度快、产率高、能耗低及操作工艺简单等优势在合成纳米金刚石、纳米氮化物、纳米氧化物、纳米碳材料等方面独树一帜。本文主要从实验分析和理论计算等多个方面分别进行研究和讨论。研究如何采用爆轰技术制备碳包覆金属纳米材料,并结合X-射线衍射仪(XRD)、透射电子显微镜(TEM)及能谱仪(EDX)、扫描电子显微镜(SEM)、拉曼光谱仪(Raman)、X光射线荧光光谱仪(XRF)、振动样品磁强计(VSM)、差热分析仪(DSC)和热失重分析仪(TG)等现代分析手段对所合成的纳米复合材料的物相成分、形貌结构、元素构成、磁性特征及前驱体热力学性能进行了分析并通过数值模拟探讨了其合成机理。在总结前人采用爆轰法合成纳米金刚石、纳米纳米管、石墨材料等基础上,首先对爆轰前驱体从氧平衡、爆炸性能、热力学性能、选择材料等方面对前驱体炸药进行初步设计。以此为出发点,首先开展了尿素硝酸盐络合物炸药爆轰合成碳包覆金属(N、Co、Fe)纳米颗粒的研究。结果表明,通过调整前驱体中元素摩尔比例,在密闭容器内惰性气体保护下,成功制备出碳包覆金属(Ni、Co、Fe)纳米材料并初步探讨了其合成机理。之后进一步开展了合成碳包覆合金纳米材料的研究。通过调整炸药前驱体中两种金属源与碳源材料的元素摩尔比例,成功地合成了碳包覆合金(FeNi、FeCo)纳米颗粒,且一次合成产率大约10～15%。再者,采用柠檬酸凝胶法对溶碳量较差的金属(以铜为代表),进行爆轰凝胶前驱体炸药合成碳包覆铜纳米材料的探索性研究。选用硝酸铜与柠檬酸按照一定摩尔比和RDX混合后形成了柠檬酸凝胶前驱体炸药,成功合成了碳包覆铜纳米材料。为了考察合成碳包覆金属(铁、钴、镍)的尿素硝酸盐络合物炸药的热安全性,分别采用DSC/TG热分析技术对其进行热分解动力学研究。通过对前驱体炸药各组分、炸药混合物及尿素硝酸盐络合物炸药的热分析并通过热分析动力学方程计算其动力学参数。结果表明,尿素络合物对金属离子的稳定作用并且遵循一定规律的动力学特征,探明了硝酸盐络合物炸药的热分解机理,为制备碳包覆金属纳米材料专用安全炸药提供了必要依据。最后,运用BKW炸药物态方程和金属的高温高压物态方程相结合并运用吉布斯最小自由能原理,通过编写GS-BKW专用程序,实现了爆轰产物与金属单质或者合金固体物态方程的耦合,并对前驱体专用炸药爆轰合成复合纳米颗粒的爆轰参数进行了数值模拟。结果表明：压力范围在9-15GPa,温度在2000-3500K之间有利于碳和金属团簇的生成并探讨了爆轰合成碳包覆金属纳米颗粒的生长机理。更多还原

【Abstract】 Since the nineties of 20 th century, CEMNPs become the another major new discovery in carbon composite materials afterwards fullerene-C60,CNTs. The new type of core-shell structural carbon/metal nanocomposites, in which graphite carbon layers arrange round spherical metal nanocrystal located in the composite center. Because that CEMNPs have excellent properties and potential broad application prospects in many areas, this kind of unique structure and physical and chemical properties of CEMNPs have aroused wide attention and research from domestic and foreign scholars in recent years. Due to the carbon shell protection, bare metal nanocrystals were prevented from aggregation and growth and provided from the oxidation resistance and environmental effect and even improved the bio-compatibility.Among these methods, detonation technique has the advantage of high efficiency, simple and lower energy consumption so that it has prepared for many nanomaterials such as nanodiamond, nano-nitride, nano-oxide, carbon nanomaterial and so on. This paper mainly explained the synthetic mechanism of CEMNPs by two ways:experiment analysis and theoretic calculation. The CEMNPs have been prepared by detonation technique and characterized by means of XRD, SEM, TEM, EDX, XRF, Raman,VSM and DSC/TG characterization methods. Finally,the synthetic mechanism of CEMNPs was presented by numerical modeling of explosive precursors.Based on a large body of evidence on detonation synthesis of nanomaterials, the OB, explosion characterization, thermal safety and composition of explosive precursors were preliminary conceived and designed, so that the carbon-encapsulated metal (Ni, Co, Fe) nanoparticles were successfully synthesized. The results showed that the explosive precursors with a certain mole ratio of nitrate and complexing agent for metallic source materials, which mixed carbon source materials such as organic matter were ignited by detonator under nitrogen in closed detonation vessel. The preliminary reaction mechanism were discussed in this part.And then Carbon-encapsulated ferronickel and ferrocobalt nanomaterials were further synthesized and characterized. The results indicated that carbon-encapsulated ferronickel or ferrocobalt nanoparticles were prepared successfully and the spherical composite nanoparticles were with a core-shell structure. The yield of synthesized composite nanoparticles was about 10-15% one time. And the compatibility of carbon and a type of metal such as copper was poor. So the another gel-precursors were prepared by mixing copper nitrate, citrate and ethylene glycol then the gel mixed with RDX for gel-explosive precursors. The gel-precursors were synthesized by detonation technique for carbon-encapsulated copper nanoparticles under argon gas in closed vessel. The explosive precursors with iron/cobalt/nickel ions or its mixtures were thermodynamically analyzed for thermal safety by DSC/TG. Base on the thermal safety analysis on characteristics of thermal decomposition of the main ingredients and their mutual effect in explosive precursors. The results showed that the best stoichiometry content of metal ions in these precursors were obtained and the DSC/TG plots method along with several thermal analysis methods were employed to determine the kinetic parameters and model of the decomposition processes for detonation synthesis of CEMNPs.Finally, Based on BKW equation of state of detonation products, and the global minimum of Gibbs free energy were applied to originally design GS-BKW programs and described chemical reacted explosive and detonation products, which realized the coupling equation of state for gas and metal or alloy products. The calculated results showed that the pressure and temperature in the range of 9-15GPa and 2000-3500K are conducive to the formation of synthesizing CEMNPs, and the growth mechanism of CEMNPs and detonation pressure and temperature were analyzed and illustrated.更多还原