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

在航空航天和发电工业中，降低燃料消耗、运行成本和温室气体排放的需求继续推动燃气涡轮机（GTE）设计者寻找提高GTE效率和延长运行寿命的方法。提高涡轮机入口温度是在不增加燃料燃烧的情况下增加功率输出的关键途径。随着涡轮机入口温度的升高、在恶劣环境下连续运行的需求以及向替代燃料的转变，热截面材料正经受增加的机械应力和环境侵蚀。虽然用于制造涡轮机叶片、轮叶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设计都需要能够在超过该温度下安全运行的材料。这只有通过使用热障涂层（TBC）系统和冷却技术才能实现。此外，许多现代高温合金由于较低的Cr含量而降低了耐环境性，这是为了在较高的温度和机械负荷下稳定微观结构。因此，现在需要热障涂层同时提供热障和环境保护功能，并且已经成为现代GTE不可或缺的组成部分。GTE设计者面临的主要挑战包括：缺乏对基体对TBC寿命影响的认识; GTE运行过程中存在元素的向内和向外扩散，导致涂层早期失效;陶瓷涂层材料的耐温性和抗断裂性不足;目前还没有一种通用的方法来预测TBC的失效机理和寿命。因此，本研究计划的目标是探索新的热障涂层材料和结构，以提高性能，了解不同使用条件下的微观结构演变和失效模式，并实现热障涂层寿命评估。本研究的成果将包括具有增强耐久性的新涂层材料成分和结构，用于不同涡轮机叶片基体材料和操作条件的涂层设计和选择协议，以及用于准确预测TBC系统寿命的工具。这项研究还将提高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。找到更耐用的涂层组合物和结构将直接使加拿大原始设备制造商（如Pratt & Whitney Canada、Magellan Aerospace）、燃气涡轮机用户（TransCanada Pipelines、Union Gas）和涂层供应商（MDS Coating Technologies、Liburdi涡轮机服务、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).