注浆法制备YSZ固体电解质及其性能研究

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	注浆法制备YSZ固体电解质及其性能研究
其他题名	Preparetion of YSZ solid electrolyte by slip casting method and its properties
	窦静
	2009-05-31
学位授予单位	中国科学院地球化学研究所
学位授予地点	地球化学研究所
学位名称	博士
关键词	钇稳定氧化锆固体电解质注浆法烧结离子电导率交流阻抗谱
摘要	以多孔石膏模具为成型载体，以8mol%钇稳定氧化锆(YSZ)粉体为原料，采用注浆法制备出具一定体积和形状的全稳定YSZ固体电解质。对注浆成型工艺中制备素坯的各个环节的主要影响因素(粘结剂种类及用量的选择、固相含量、球磨时间等)与浆料稳定性、流动性及素坯密度之间进行优化实验，确定了制备悬浮稳定、流动性好的浆料的实验参数。将利用上述浆料于多孔石膏模中成型后的素坯进行等静压操作，进一步提高其致密度，为制备致密化高的电解质材料奠定了条件。结果表明：注浆成型后的素坯在进一步等静压处理后相对密度可达53%左右，可以说注浆成型法是一种成型具一定体积素坯的简单可行的方法。继而将成型后的素坯于不同的烧结条件下进行常压烧结，并对烧结后YSZ固体电解质的致密化程度、微观形貌(SEM)及导电性能进行测量和表征，借助于交流阻抗谱测量其导电性，采用氧浓差电池法测定其离子迁移数(能斯特响应)。通过对烧结体的性能分析，建立其致密程度、导电性与烧结条件之间的关系，并以此为依据来优化烧结工艺。结果表明：样品的致密度随烧结温度和烧结时间的增加而提高，电导率随着致密度的提高而不断增加，其中在1550℃烧结3h的电解质制品500℃时的阻抗测试结果表明其离子导电率已超过投入实际使用的最小限定值；结合样品的微观形貌分析，在较高的烧结温度下晶粒增长显著，平均粒径可以达到微米级，而低温下增长不显著。立足于砖层模型和多晶电解质晶界空间电荷层导电特性，对不同粒径的YSZ多晶固体电解质材料的晶界电导进行分析，结果表明随平均粒径的减小，YSZ多晶固体电解质材料晶界空间电荷层电势减小，而其中氧空位浓度增加，因此可以说，对高纯物质而言，晶粒的减小有助于提高其整体电导性。因而就优化烧结工艺而言，要制备高性能YSZ固体电解质可以以达到高致密度、抑制晶粒显著生长为原则来进行探讨。
其他摘要	Totally stabilized YSZ solid electrolyte with a certain volume and desirable geometric shape had been prepared by slip casting method with 8 mol % yttria stabilized zirconia (YSZ) powder and the polyporous plaster mold being as shaping manner. Mostly influence factors in the slip casting procedure， to be specific， the types and contents of dispersant and binder， YSZ powder solid content， milling time， etc. were discussed， by operating the optimization experiments on the above factors， series of optimal parameters for stable suspension with sound flowability and very few bubbles were established. In addition， the green samples were pressed through isostatic pressing before sintering in order to get a more probability for the well densified samples. The results show that the density of the green samples can reach 53% more or less after the isostatic pressing， so we can say the slip casting method is an easy and feasible way for preparing samples with a certain shape. In the present work， the sintering was first to be conducted in the temperature range of 1350～1550 ℃， 3 hours， respectively. Then the density of YSZ was measured by Archimedes displacement method. And the line shrinkage was calculated from measuring the dimensions before and after sintering. XRD analysis was conducted to verify phase structure for both the powder and YSZ electrolytes. The photomicrographs of fracture surfaces were observed via scanning electron microscopy. And the electrical properties of samples under different sintering temperatures were obtained by complex impedance method. Study and analysis for the effect of sintering temperature on the densification and electrical properties were performed. The research results show as follows: pure cubic phase of the powder as well as YSZ electrolytes is affirmed by XRD; the microstructure of samples has a great influence on it’s density and conductivity; sintering at 1550 ℃ for 3 hours， the YSZ electrolyte has characteristics of symmetrical grain， dense packing， more than 96% of theoretical density and oxygen ionic conductivity of 2.97×10-3 S•cm-1 at 500℃. For a high quality YSZ solid electrolyte， its conductivity and mechanical properties are directly influenced by its grain size， to the authors’ best knowledge the grain fined electrolytes have much better conductivity and mechanical properties than the opposite ones， especially for the nano-scale materials. However， it is well known that the conventional heating treatment at a very high temperature for a long time certainly brings the grain extraordinary growth. In view of this， this dissertation applies the present basic theory related to the conductivity of YSZ solid electrolytes， that is Schottky barrier model and Oxygen vacancy concentration depletion in the grain boundary space charge layers. Within this framework， the space charge potential and the depletion of oxygen vacancy concentration were calculated， it was found that space charge potential decreased， but the concentration of oxygen vacancy increased with the decreasing grain size. Therefore， for the high purity electrolytes， the decreasing of grain size can improve the whole performance， including conductivity and mechanical properties. The above analysis supplies us a new angle for sintering YSZ solid electrolytes without extraordinary grain growth at a lower temperature in the future.
页数	64
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/3498
专题	研究生_研究生_学位论文
推荐引用方式 GB/T 7714	窦静. 注浆法制备YSZ固体电解质及其性能研究[D]. 地球化学研究所. 中国科学院地球化学研究所,2009.

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