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首页> 外文学位 >Processing-structure-property relationships of thermal barrier coatings deposited using the solution precursor plasma spray process.
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Processing-structure-property relationships of thermal barrier coatings deposited using the solution precursor plasma spray process.

机译：使用溶液前驱体等离子喷涂工艺沉积的热障涂层的加工结构与性能的关系。

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摘要

This research is intended to develop a novel process, solution-precursor plasma-spray (SPPS), for the deposition of highly durable thermal barrier coatings (TBCs). In the SPPS process a solution precursor feedstock, that results in ZrO2-7 wt% Y2O3 ceramic, is injected into the plasma jet and the coating is deposited on a metal substrate. The formed coating has the following novel microstructural features: (i) ultra-fine splats, (ii) through-thickness cracks, (iii) micrometer and nanometer porosity, and (iv) interpass boundaries.; The deposition mechanisms of the solution precursor droplets injected into the different regions of the plasma jet were found to be different due to large temperature variation across the plasma jet. The solution precursor droplets injected into the core of the plasma jet are deposited on the substrate as ultra-fine splats that account for around 65 volume% of the coating. The other 35 volume% of the coating includes porosity and deposits formed from the solution precursor droplets injected into other regions of the plasma jet.; The optimum processing condition for highly durable TBCs was determined using Taguchi design of experiments. Meanwhile, the relationship of the microstructural features and processing parameters was revealed.; During thermal cycling, the unmelted particles in the coating were observed to pyloyze and/or sinter, while no sign of sintering was observed for the ultra-fine splats. The spacing of through-thickness cracks remains in the range of 160 to 190 μm throughout the thermal cycling test. Three stages of oxidation of the bond coat were observed.; Failure of the SPPS TBC starts with the crack nucleation along the unmelted particles in the top coat and the Ni, Cr, Co-rich oxides of large thickness. These cracks propagate and coalesce with thermal cycling. The extensive cracking of the rapidly formed Ni, Cr, Co-rich oxides resulting from the depletion of aluminum in the bond coat leads to the development of large separation between TBC and substrate. When a separation of sufficient size emerges, the TBC starts to separate from the metal substrate by large scale buckling as a result of the small strain energy stored in the strain tolerant SPPS TBCs.
机译：这项研究旨在开发一种新工艺，溶液前体等离子体喷涂（SPPS），用于沉积高度耐用的热障涂层（TBC）。在SPPS工艺中，将溶液前驱体原料注入等离子体中，该原料产生ZrO 2 -7 wt％Y 2 O 3 陶瓷喷射，涂层沉积在金属基材上。形成的涂层具有以下新颖的微观结构特征：（i）超细小片;（ii）贯穿厚度的裂纹;（iii）微米和纳米孔隙率;以及（iv）层间边界。发现由于等离子体喷嘴两端的温度变化大，注入到等离子体喷嘴的不同区域中的溶液前驱物液滴的沉积机理不同。注入等离子流核心的溶液前驱液滴以超细小片的形式沉积在基板上，占涂层的65％（体积）。涂层的其余35体积％包括孔隙率和由注入到等离子体射流的其他区域中的溶液前体液滴形成的沉积物。使用Taguchi设计的实验确定了高度耐用的TBC的最佳加工条件。同时揭示了微观结构特征与加工参数的关系。在热循环过程中，观察到涂层中未熔化的颗粒热解和/或烧结，而超细板未观察到烧结迹象。在整个热循环测试中，贯穿厚度裂纹的间距保持在160至190μm的范围内。观察到粘结层的三个氧化阶段。 SPPS TBC的失效始于沿面涂层中未熔融颗粒的裂纹形核，以及厚厚的Ni，Cr，Co富氧化物。这些裂纹随着热循环而扩展并合并。由于粘结层中铝的消耗而导致快速形成的富Ni，Cr，Co富集氧化物的大量开裂，导致TBC与基材之间出现较大的分离。当出现足够大小的分离时，由于在耐应变的SPPS TBC中存储的应变能量较小，TBC开始通过大规模屈曲而与金属基板分离。

著录项

  • 作者

    Xie, Liangde.;

  • 作者单位

    The University of Connecticut.;

  • 授予单位 The University of Connecticut.;
  • 学科 Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 215 p.
  • 总页数 215
  • 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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