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Microstructural development and the evolution of defects in constrained and sinter-forged ceramics.

机译：约束和烧结锻造陶瓷的微观结构发展和缺陷演变。

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摘要

In this study, the microstructural evolution of uniaxial loaded, or constrained sintered YSZ compacts and the growth of cracks and defects in constrained ceramic films is reported. It is shown that a uniaxial load applied to a YSZ compact will lead to a modified densification. In addition to a modified densification, the pore structure is shown to exhibit an anisotropic modification from the applied load, the magnitude of anisotropy increasing with load, temperature, and localized density. Further investigation of this anisotropic micro-pore behavior with artificial controlled sized pores shows that there is a critical pore size at which the behavior changes from that of nano-pores to that of micro-pores.; The growth of cracks and holes in constrained YSZ films is investigated by introducing artificial defects with a Focused Ion Beam into green centrifuge-cast YSZ films. This technique for studying defect growth allows micron scale defects to be introduced into a fragile green film for sintering studies. Stress concentrations near defects will lead to increased damage and crack growth in the films. Channel cracks are observed in the films with introduced defects, and are absent in films without defects. Sintering cracks are observed in some samples with high interfacial friction and large thickness. From analyzing the percent of each crack growth, small crack to large crack behavior transition point is observed.; Currently, most densification models assume isotropic sintering behavior. It is shown in this study that assumption is inaccurate. This research has increased the knowledge base of anisotropic microstructure evolution, an area that is currently not very well understood but applicable to many important systems.
机译：在这项研究中，报告了单轴加载或受约束的烧结YSZ压块的微观结构演变以及受约束的陶瓷膜中裂纹和缺陷的增长。结果表明，施加到YSZ压块上的单轴载荷将导致改进的致密化。除了改进的致密化，孔隙结构还显示出施加载荷的各向异性变化，各向异性的大小随载荷，温度和局部密度的增加而增加。对具有人工控制尺寸的孔的各向异性微孔行为的进一步研究表明，存在一个临界孔径，在该临界孔径下，行为会从纳米孔变为微孔。通过用聚焦离子束将人工缺陷引入到绿色离心铸造的YSZ膜中，研究了约束YSZ膜中裂纹和孔的生长。这种用于研究缺陷生长的技术允许将微米级的缺陷引入到易碎的生膜中进行烧结研究。缺陷附近的应力集中将导致膜中的损伤增加和裂纹扩展。在具有引入的缺陷的膜中观察到通道裂纹，而在没有缺陷的膜中不存在通道裂纹。在一些具有高界面摩擦和较大厚度的样品中观察到烧结裂纹。通过分析每个裂纹扩展的百分比，可以观察到从小裂纹到大裂纹行为的转变点。当前，大多数致密化模型假定各向同性的烧结行为。这项研究表明，假设是不正确的。这项研究增加了各向异性微观结构演化的知识基础，该领域目前尚不十分清楚，但可应用于许多重要系统。

著录项

  • 作者

    Frame, Dustin Michael.;

  • 作者单位

    University of Washington.;

  • 授予单位 University of Washington.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 149 p.
  • 总页数 149
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;
  • 关键词

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