碳化硅纳米点阵诱导高纯度多晶致密碳化硅陶瓷的制备与性能优化

Silicon carbide plays an important role in the high temperature heat, and extreme environments, due to its high strength, high thermal resistance and excellent semiconductor properties. Based on the research about preparation of silicon carbide ceramics through in-situ SiC nucleation and growth on carbon substrate, using high temperature physical vapor transport, an idea of combination of silicon carbide nano arrays prepared by chemical vapor deposition (CVD) and growth of silicon carbide polycrystalline ceramics by physical vapor transport (PVT) is proposed. It is proposed that the SiC arrays can be grown by PE-CVD technique with ultra-thin template, and also their microstructure and nano-crystalline state are controlled during growth process., and polycrystalline dense silicon carbide ceramics is prepared by taking the SiC nano arrays as nucleus and using high-temperature PVT growth. Formation mechanism of amorphous silicon carbide nano arrays and law of the recrystallization will be studied, as well as their effect on silicon carbide ceramics prepared by PVT method. The effect of starting materials, the atmosphere composition, temperature and temperature gradients et al. on the microstructure of the silicon carbide ceramics will be further studied, and law of materials performance optimization will ve investigated, and the growth model of polycrystalline silicon carbide prepared by PVT will be obtained. Due to the speciality of the preparation process, the purity of the silicon carbide ceramic materials is very high, and the directionally micrustructure will be refined, so the materials will possess excellent mechanical, physical and chemical properties. The research result not only has academic value, but also has important practical significance in practical applications with high temperature, corrosion, et. al.

碳化硅陶瓷具有高强度、高耐热性和优异的半导体性能，在高温耐热及极端环境下可发挥重要的作用。利用高温气相传输法，通过石墨衬底原位碳化硅成核生长制备出了碳化硅陶瓷，在此基础上，本课题提出化学气相沉积（CVD）制备碳化硅纳米点阵与物理气相传输（PVT）生长碳化硅多晶陶瓷相结合的思想，拟通过PE-CVD结合超薄模板制备结构和组织可控的碳化硅纳米点阵列，以此为核心使用高温PVT技术生长多晶致密碳化硅陶瓷。研究非晶碳化硅纳米点阵的形成机理和再结晶规律，以及对PVT法制备的碳化硅陶瓷影响，研究PVT过程的源材料、气氛组成、温度及温度梯度等因素对碳化硅陶瓷的组织的影响，探讨材料性能优化的影响规律，获得PVT制备多晶碳化硅的生长模型。由于制备过程的特殊性，碳化硅陶瓷材料的纯度极高，定向组织得到细化，材料具有优异的力学与理化性能。研究结果不但具有学术价值，而且在实际高温、腐蚀等的应用场合也具有重要的现实意义。

高性能碳化硅陶瓷的制备需要特殊的制备方法，利用高温气相传输法制备的多晶碳化硅陶瓷材料具有高纯度、高密度和高强度，在高温耐热及极端环境下可发挥重要的作用。在本基金项目的资助下，重点开展了高纯度、高密度和高强度碳化硅陶瓷材料的制备技术、结构调控和性能等方面的研究。采用孔径80nm、孔深200nm的网格结构的阳极氧化铝（AAO）模板，利用等离子体增强化学气相沉积制备非晶碳化硅纳米点阵，研究碳化硅点阵的形成机理，进一步研究非晶碳化硅的再结晶规律，探讨纳米点阵碳化硅的晶体取向和组织结构的形成规律，获得了颗粒尺寸和排布均匀，有明显的网络结构的纳米碳化硅点阵结构，为碳化硅点阵诱导碳化硅材料的制备提供基础；研究采用纳米碳化硅颗粒为晶种诱导碳化硅生长及其原生面形貌以及不同碳源衬底对碳化硅陶瓷的组织和性能的影响，并对其织构特征进行了定量计算和解释，证明了50 nm、500 nm晶种诱导和无晶种诱导所制得的碳化硅陶瓷都具有沿(0 0 0 6)晶面的择优取向，探讨纳米碳化硅颗粒为晶种诱导生长出的碳化硅陶瓷的力学性能及其影响规律，采用晶种诱导后碳化硅陶瓷的微观组织得到了细化，力学性能得到了改善。研究使用不同尺寸和晶型的SiC粉为蒸发原料的制备碳化硅多晶致密陶瓷的工艺因素，探讨原料因素对材料成核长大过程的作用机理，揭示组织的形成机理与优化、以及对性能的影响规律，获得了纳米粒度的粉料形成的细小晶粒尺寸，排布也致密的材料，证明了β-SiC原料在相同温度下分解速率更快，沉积获得的碳化硅陶瓷晶粒尺寸较小的结论。研究成果为该材料在高温、辐照等严酷环境下的应用提供研究基础。 在本项目实施过程中，共培养博士生7名（毕业5名），硕士生10名（毕业6人）。共发表学术论文26篇（全部有基金标注），其中SCI收录24篇，EI收录3篇。相关成果共获得授权的中国发明专利3项；新申请3项。