氧化锆纳米陶瓷的制备及其烧结机理研究

发布时间：2018-01-07 19:10

本文关键词：氧化锆纳米陶瓷的制备及其烧结机理研究　出处：《湖北工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：纳米陶瓷是先进陶瓷的未来发展方向。本文选择3Y-TZP纳米陶瓷作为研究对象。材料的微观结构决定其宏观性能,因此对材料的化学组份,微观结构的设计以及烧结机制的控制是制备纳米陶瓷的关键。Y-TZP材料具有优良的力学性能,在生产生活中被广泛应用。本文综述了Y-TZP陶瓷的原料及制备工艺、组成优化、超塑性和耐磨性的研究进展,重点讨论了Y-TZP陶瓷在齿科中的应用现状和前景,而Y-TZP陶瓷低温老化现象限制了它的应用。论文总结了影响Y-TZP陶瓷低温老化的三个因素,即稳定剂的种类与含量、晶粒尺寸的大小以及剩余应力的存在,并提出几种防止低温老化的措施。制备更加微观细化的纳米Y-TZP陶瓷是保护材料不发生相变的解决方案,对比两步烧结法和SPS烧结法,可知两步法烧结中气孔出现了大尺度的异常生长,而SPS烧结具有高速升温、降温的特点,能够对于烧结过程中晶粒尺寸与烧结颈部尺寸进行掌控;此外,SPS技术具有更宽的压力范围,能够实现烧结压力的灵活的调控。因此,本研究选择SPS技术作为烧结手段开展研究。经典“三段式”烧结理论认为:以晶粒作为基本单元的“颗粒重排”主导烧结初期的密实化行为,但是对于烧结的贡献十分有限,仅限于初期样品收缩的2%~3%;进入烧结中后期,微观结构由于扩散颈部形成而逐渐“冻结”导致“颗粒重排”失效,因此烧结过程仅受到单一原子扩散相关过程主导。基于这一理论,现有陶瓷的制备中往往强调原子扩散相关行为对于烧结过程的作用,而对于“颗粒重排”相关过程并未引起足够的重视。经典理论的建立是基于传统粗晶陶瓷材料的烧结,但是随着纳米材料的迅速发展,其中的一些局限性也逐渐显现。本论文将对3Y-TZP纳米陶瓷在SPS烧结过程中的“颗粒重排”行为进行探索研究。通过模具设计,对SPS烧结过程中电场、升温速率、压力等因素进行逐一分离,在烧结行为表征中,同时引入相对密度、晶粒尺寸与“最大气孔尺寸”的综合考量。通过研究工艺参数对颗粒重排行为的影响,对纳米陶瓷烧结过程中异于传统理论的颗粒重排行为的动力学成因进行解释,探究“颗粒重排”在纳米陶瓷烧结中有效作用阶段与相关作用,进一步对3Y-TZP纳米陶瓷低温老化性能展开研究。
[Abstract]:Nano-ceramics are the future development direction of advanced ceramics. In this paper, 3Y-TZP nano-ceramics are chosen as the research object. The microstructure of the materials determines their macroscopic properties, so the chemical components of the materials are determined. The design of microstructure and the control of sintering mechanism are the key to the preparation of nano-ceramics. Y-TZP materials have excellent mechanical properties. Y-TZP ceramics are widely used in production and life. In this paper, the research progress of Y-TZP ceramics, such as raw materials, preparation process, composition optimization, superplasticity and wear resistance, is reviewed. The application status and prospect of Y-TZP ceramics in dentistry were discussed in detail. The application of Y-TZP ceramics is limited by the phenomenon of low temperature aging. This paper summarizes the three factors that affect the low temperature aging of Y-TZP ceramics, that is, the types and contents of stabilizers. The existence of grain size and residual stress, and some measures to prevent low temperature aging are put forward. It is a solution to protect the material from phase transformation by preparing more micro-fine Y-TZP ceramics. Compared with the two-step sintering and SPS sintering, it can be seen that there are large scale abnormal growth of pores in two-step sintering, while SPS sintering has the characteristics of high-speed heating and cooling. Can control the grain size and the size of the sintering neck during the sintering process; In addition, SPS technology has a wider pressure range, which can realize the flexible control of sintering pressure. In this study, SPS technology was chosen as the sintering method. The classical "three-stage" sintering theory holds that the "particle rearrangement" with grain as the basic unit dominates the densification behavior in the initial stage of sintering. However, the contribution to sintering is very limited, which is limited to 2 / 3 of the initial sample shrinkage. In the middle and late stage of sintering, the microstructure is gradually "frozen" due to the formation of diffusion neck, which leads to the failure of "particle rearrangement", so the sintering process is only dominated by the single atom diffusion related process. The effect of atomic diffusion behavior on sintering process is often emphasized in the preparation of existing ceramics. The classical theory is based on the sintering of traditional coarse grained ceramic materials, but with the rapid development of nanomaterials. In this paper, the "particle rearrangement" behavior of 3Y-TZP nanocrystalline ceramics during SPS sintering is studied. The electric field, heating rate and pressure during SPS sintering were separated one by one, and the relative density was introduced in the sintering behavior characterization. The effect of process parameters on particle rearrangement behavior was studied by considering the grain size and "maximum pore size". The dynamic causes of particle rearrangement in the sintering process of nanocrystalline ceramics were explained, and the effective stages and related effects of particle rearrangement in the sintering process of nano-ceramics were explored. The low temperature aging properties of 3Y-TZP nanoceramics were further studied.
【学位授予单位】：湖北工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ174.1

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