首页> 外文期刊>Journal of Thermal Spray Technology >Heat Transfer Through Plasma-Sprayed Thermal Barrier Coatings in Gas Turbines: A Review of Recent Work
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Heat Transfer Through Plasma-Sprayed Thermal Barrier Coatings in Gas Turbines: A Review of Recent Work

机译:燃气轮机中通过等离子喷涂热障涂层进行传热:近期工作回顾

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A review is presented of how heat transfer takes place in plasma-sprayed (zirconia-based) thermal barrier coatings (TBCs) during operation of gas turbines. These characteristics of TBCs are naturally of central importance to their function. Current state-of-the-art TBCs have relatively high levels of porosity (~15%) and the pore architecture (i.e., its morphology, connectivity, and scale) has a strong influence on the heat flow. Contributions from convective, conductive and radiative heat transfer are considered, under a range of operating conditions, and the characteristics are illustrated with experimental data and modeling predictions. In fact, convective heat flow within TBCs usually makes a negligible contribution to the overall heat transfer through the coating, although what might be described as convection can be important if there are gross through-thickness defects such as segmentation cracks. Radiative heat transfer, on the other hand, can be significant within TBCs, depending on temperature and radiation scattering lengths, which in turn are sensitive to the grain structure and the pore architecture. Under most conditions of current interest, conductive heat transfer is largely predominant. However, it is not only conduction through solid ceramic that is important. Depending on the pore architecture, conduction through gas in the pores can play a significant role, particularly at the high gas pressures typically acting in gas turbines (although rarely applied in laboratory measurements of conductivity). The durability of the pore structure under service conditions is also of importance, and this review covers some recent work on how the pore architecture, and hence the conductivity, is affected by sintering phenomena. Some information is presented concerning the areas in which research and development work needs to be focussed if improvements in coating performance are to be achieved.
机译:本文对燃气轮机运行过程中等离子喷涂(基于氧化锆的)热障涂层(TBC)中的热传递进行了综述。 TBC的这些特性自然对其功能至关重要。当前最先进的TBC的孔隙率相对较高(约15%),孔结构(即其形态,连通性和结垢)对热流有很大影响。在一定范围的运行条件下,考虑了对流,传导和辐射传热的贡献,并通过实验数据和模型预测说明了这些特性。实际上,TBC内的对流热流通常对通过涂层的整体热传递的贡献微不足道,尽管如果存在明显的贯穿厚度缺陷(例如分段裂纹),则对流可能很重要。另一方面,取决于温度和辐射散射长度,辐射传热在TBC内可能很重要,而这又对晶粒结构和孔结构敏感。在当前感兴趣的大多数条件下,传导热传递是主要的。然而,重要的不仅是通过固体陶瓷的传导。取决于孔的结构,通过孔中的气体的传导可以起重要作用,尤其是在燃气轮机中通常使用的高气压下(尽管在实验室电导率测量中很少使用)。在使用条件下孔结构的耐久性也很重要,该综述涵盖了有关烧结现象如何影响孔结构以及导电性的最新研究。提出了一些有关要提高涂层性能需要重点研究和开发工作的领域的信息。

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