Advanced Thermal Barrier Coating Systems for Gas Turbine Application: Microstructure, Properties, and Performance

在航空航天和发电行业，降低燃料消耗、运行成本和温室气体排放的需求不断推动燃气涡轮发动机（GTE）的设计者寻找提高GTE效率和延长使用寿命的方法。提高涡轮进口温度是在不增加燃油消耗的情况下提高功率输出的关键途径。随着涡轮进口温度的上升，恶劣环境下持续运行的需求，以及向替代燃料的转变，热截面材料正在承受越来越大的机械应力和环境攻击。虽然用于制造涡轮叶片、叶片和燃烧部件的最先进的高温合金可以在高达1093°C（2000°F）的温度下保持强度，但大多数当前和所有下一代GTE设计都需要能够安全运行的材料远远超过该温度。这只能通过使用热障涂层（TBC）系统和冷却技术来实现。此外，由于Cr含量较低，许多现代高温合金的耐环境性降低，以稳定高温和机械载荷下的微观组织。因此，TBCs现在需要提供热障和环保功能，并已成为现代gte不可或缺的一部分。由于业界的目标是将TBC指定为GTE设计中的“主要依赖”，因此需要进一步提高TBC的性能和可靠性。GTE设计者面临的主要挑战包括：缺乏对衬底对TBC寿命影响的理解；GTE运行过程中元素向内扩散和向外扩散导致涂层早期失效；陶瓷面漆材料耐温性和抗断裂性不足；缺乏基于微观结构和使用状况预测TBC失效机理和寿命的通用方法。因此，本研究计划的目标是探索新的TBC材料和结构，以提高其性能，了解不同使用条件下的微观结构演变和失效模式，并实现TBC寿命评估。这项研究的成果将包括新的涂层材料组合和结构，增强耐用性，涂层设计和选择协议，不同的涡轮叶片基材材料和工作条件，以及准确预测TBC系统寿命的工具。这项研究还将加强对极端机械和环境条件下涂层和基材相互作用的理解，并为hqp提供培训。寻找更耐用的涂层成分和结构将直接使加拿大的原始设备制造商（如Pratt & Whitney Canada， Magellan Aerospace），燃气轮机用户（TransCanada Pipelines, Union gas）和涂层供应商（MDS coating Technologies, Liburdi turbine Services, Northwest Mettech）受益。

In the aerospace and power generation industries, demands to reduce fuel consumption, operating costs, and greenhouse gas emissions continue to push gas turbine engine (GTE) designers to find ways to improve GTE efficiency and extend operating lives. Increasing the turbine inlet temperature is a key way to increase power output without increasing fuel burn. With rising turbine inlet temperatures, demands for continuous operation under harsh environments, and a shift towards alternative fuels, hot section materials are being subjected to increased mechanical stresses and environmental attack. While state-of-the-art superalloys used to manufacture turbine blades, vanes, and combustion components can maintain strength at temperatures up to 1093°C (2000°F), most current and all next generation GTE designs require materials that can safely operate well beyond this temperature. This is only possible with the use of thermal barrier coating (TBC) systems and cooling technology. In addition, many modern superalloys have reduced environmental resistance due to lower Cr content, done to stabilize the microstructure under higher temperatures and mechanical loads. Therefore, TBCs are now required to provide both thermal barrier and environmental protection functions, and have become integral to modern GTEs. With the industry's goal to designate TBCs as a "prime reliant" in GTE design, further TBC performance improvement and reliability are needed.Major challenges GTE designers face include: lack of understanding of substrate influence on TBC life; the existence of inward and outward diffusion of elements during GTE operation leading to early coating failure; insufficient temperature and fracture resistance of ceramic top coat materials; and lack of a universal approach to predict TBC failure mechanism(s) and life based on microstructure and service condition. Therefore, the objectives of this research program are to explore new TBC materials and structures for improved performance, to understand the microstructure evolution and failure mode(s) under different service conditions, and to enable TBC life assessment.The outcomes of this research will include new coating material compositions and structures with enhanced durability, a coating design and selection protocol for different turbine blade substrate materials and operating conditions, and a tool to accurately predict TBC system life. This research will also enhance the understanding of coating and substrate interaction under extreme mechanical and environmental conditions and provide training to HQPs. Finding more durable coating compositions and structures will directly benefit Canadian OEMs (such as Pratt & Whitney Canada, Magellan Aerospace), gas turbine users (TransCanada Pipelines, Union Gas) and coating providers (MDS Coating Technologies, Liburdi Turbine Services, Northwest Mettech).