【作者】 余庚；

【导师】 王为民；

【作者基本信息】 武汉理工大学 ， 材料物理与化学， 2011， 硕士

【摘要】 二硼化钛陶瓷（Titanium diboride,TiB2）是一种新型的工程陶瓷材料,它具有优良的耐高温性、高硬度、高模量和低比重,同时还具有优良的抗冲击能力,二硼化钛以其优异的综合性能成为国防建设关键新材料之一。但TiB₂陶瓷材料脆性大、不易加工、抗热震性差等问题限制了其进一步应用,因此如何进一步提高二硼化钛陶瓷的强韧性是目前研究的关键问题之一。而目前采取的技术手段主要是细化材料晶粒和第二相弥散强化技术,但是由于TiB2纳米粉末的制备十分困难,同时烧结条件相当苛刻,因此,TiB₂超细晶粒陶瓷的制备研究进展不大,目前的研究主要集中在第二相弥散强化上。本论文采用前驱体原位合成法制备TiB2/SiC纳米复合粉体,并详细研究了前驱体热解法制备纳米SiC。采用热压烧结技术和SPS烧结技术对制备得到的复合粉体进行烧结,对其进行分析表征,研究其结构性能之间的关系。首先研究了前驱体热解法制备纳米SiC。通过控制前驱体热解时的升温速率来控制纳米SiC的形貌,并对纳米SiC的热稳定性进行了研究。利用MICROS细化设备对前驱体进行细化处理以得到分散较好的纳米SiC。通过研究发现：利用前驱体热解法能够制备得到分散良好的纳米SiC粉体。采用前驱体原位合成的方法制备得到了TiB2/SiC纳米复合粉体,发现前驱体热解产物在复合粉体中起到一种类似粘结剂的作用,将TiB₂颗粒粘结在-起。复合粉体在高温条件下,体系内的各成分及热解产物之间是相互稳定的,并不会发生化学反应,也不会破坏复合粉体各组分之间的相互结构；随着温度的升高,SiC的结晶越来越好。利用热压烧结对制备得到的复合粉体进行烧结,得到的烧结体结构均匀致密,颗粒无异常长大,各物相之间相对稳定,没有引入其他杂质,结晶后的SiC存在于TiB₂晶粒之间,形成纳米复相结构。分别用细化后的TiB2和前驱体制备TiB2/SiC纳米复合粉体,细化后的粉体粒径较小,比表面积较大,表面活性变大,更利于复合粉体之间的结合。复合粉体在热解后用行星球磨细化处理以破坏粉体之间的团聚,更利于烧结。采用SPS烧结技术对细化后的复合粉体进行烧结。研究表明：TiB2/SiC复合粉体SPS烧结后,块体的显微结构均匀,致密,颗粒细小。更多还原

【Abstract】 Titanium diboride (TiB2) is a new engineering ceramic material, with excellent temperature resistance, high hardness, high modulus and low specific gravity, also has an excellent thermal shock resistance, so it becomes a new key material of national defense as its excellent performance. But the brittle, difficult process, and poor thermal shock resistance of TiB2 limits its application in future, so how to improve the strength and toughness of TiB2 is one of the key issues at present. And now, most of people take the techniques that refine the grain and the second-phase dispersion strengthening to improve the strength and toughness of TiB2, but it is difficult to refine the grain of TiB2, while the sintering conditions can be quite harsh, so refine the grain of TiB2 is in little progress, and most study focused on the technique of second-phase dispersion strengthening.In this thesis, TiB2/SiC nano-composite were prepared by the in situ synthesis of precursor, and the nano SiC that prepared from precursor were studied detailed. The TiB2/SiC composite were sintered by hot press sintering (HP) and spark plasma sintering (SPS), its characterization were studied to research the relationship between structure and properties.First, the nano SiC that prepared from precursor were studied. The morphology of nano-SiC were controlled by control the heating rate during pyrolysis, and the thermal stability of nano-SiC was studied. Well dispersed nano-SiC were obtained by refine the precursor using the equipment of MICROS. It could be found that:well dispersed nano SiC could be prepared by using the pyrolysis of precursor.TiB2/SiC composite could be get by using the in situ synthesis of precursors, it could be found that the pyrolysis products of precursor played a binder role in the composite to bond the TiB2 particles together. The components within the system and the pyrolysis products were mutually stable, they didn’t react with each other, and they also didn’t undermine the structure between each other when the composite were in high temperature. For the SiC, the higher the temperature the better crystallization. The prepared composite was sintered by HP sintering, the structure of sintered body was uniform and compact, there was no grain growth abnormal and no impurities in sintered body after sintering. The phases in composite were stability with each other, and the crystallized SiC grains existed between TiB2 to formed the structure of nanocomposite.TiB2/SiC composite were prepared by using the refined TiB2 and precursor. Refined powder had smaller particle size, large specific surface area, and their surface activity became better which it is conducive to the binding between the components of composite. The composite after pyrolysis was refined by the planetary ball mill to disrupt the reunite of composite which was conducive to sintering. The refined composite was sintered by SPS. It could be found that:the structure of the sintered TiB2/SiC composite by SPS was uniform and compact, the grain were small.更多还原