【作者】 夏敏；

【导师】 葛昌纯；

【作者基本信息】 西南交通大学 ， 材料学， 2013， 博士

【摘要】 制备耐高温一维纳米材料,探索其合成方法、调控机制,实现对纳米结构的调控大量制备,对深入研究材料结构与性能的关系,和耐高温一维纳米材料在高温结构材料增强增韧上具有重要的应用意义。本论文在Si-C-N-W体系中,选取了几种典型的耐高温一维纳米材料进行研究(氮化硅、碳化硅、碳纳米管、钨),探索了能够大量制备上述一维纳米材料的合成方法,围绕一维纳米结构材料的调控制备、形貌演化规律、微观结构变化规律与生长机制进行了系统的研究,摸清其生长特性与合成条件的依赖关系。第三章中,采用燃烧合成技术,研究了W为催化剂对氮化硅纳米线形貌和结构的影响,提出了气-固(Vapor-Solid,VS)生长机理,通过原位透射电镜技术,测试了单根氮化硅纳米线的弯曲模量,为氮化硅纳米线的调控生长以及氮化硅纳米线在高温结构材料中的应用打下了良好基础。第四章中,基于燃烧合成技术,在Si-C-N体系中,以硅粉和聚四氟乙烯为原料,在氮气气氛下,研究了PTFE加入量对碳化硅纳米线形貌、结构、相组成的影响,研究了W和Ti催化剂对碳化硅纳米线品质影响,在W催化Si-C-N体系中,首次发现并提出了碳化硅纳米线新的生长机理“Si-C-N体系中Si3N4纳米线中间体模板诱导SiC纳米线生长的生长机理”,在Ti催化的Si-C-N体系中,发现并证实了碳化硅纳米线的气-液-固(Vapor-Liquid-Solid, VL)生长机理,最后大量制备了碳化硅纳米线。利用原位通过原位透射电镜技术,测试了单根碳化硅纳米线的弯曲模量。实验结果为碳化硅纳米线在高温结构材料中的应用奠定了重要的基础。第五章中,基于真空加热技术,研究了升温速度对非晶碳纳米管形貌、结构的影响,探讨了升温速度对非晶碳纳米管调控生长的作用机理,在此基础上,大量制备了长径比可调控的非晶碳纳米管,并对非晶碳纳米管的高温石墨化行为进行了系统研究。第六章中,以非晶碳纳米管为模板,探索了气相沉积法和湿化学法制备W纳米线的可行性,并通过湿化学法制备了W纳米线,研究了非晶碳纳米管为模板通过湿化学法制备W纳米线的生长机理。更多还原

【Abstract】 To apply high-temperature1-D nanostructures in the high-temperature structural materials, it is necessary to explore large-scale synthesis methods. For this reason, it is important to prepare1-D nanostructures with controllable and tunable properties, and study the microstructure and performance relationship.In this study, we have studied several high-temperature1-D nanostructures (Si3N4, SiC, amorphous CNT, and W) in Si-C-N-W system. In Chapter3, we studied the growth mechanism of W-catalyzed Si3N4nanowires via self-propagating high-temperature synthesis process (SHS), and found how W affects the morphology and structure of Si3N4nanowires. Finally we studied the elastic bending modulus of single Si3N4nanowires by in-situ TEM technology. In Chapter4, we prepared SiC nanowires in large scale by SHS process in Si-C-N system, and studied the catalyst effect of W and Ti, and found how PTFE affects the phase, morphology, microstructure, yields of SiC nanowires. Similarly, we also studied the elastic bending modulus of single SiC nanowires by in-situ TEM technology. In this chapter we reported a novel growth mechanism of W catalyzed SiC nanowires in Si-C-N system by HRTEM and EELS techniques, named "Intermediate template directed SiC nanowire growth in Si-C-N systems". Furthermore, we have confirmed the VLS growth mechanism of Ti catalyzed SiC nanowires in this system. In Chapter5, tunable amorphous CNT were prepared in large-scale by vacuum heating process. By adjusting the heating rate, amorphous CNT with different aspect ratios were prepared. We studied the growth mechanism of tunable amorphous CNT, and studied the crystallization behavior of amorphous CNT at high temperature. In Chapter6, W nanowires were prepared by using amorphous CNT as template, we studied the growth mechanism of this template assisted W nanowires更多还原