3-8. Failure mechanism and reliability assessment of gas turbine thermal barrier coatings

Yichun Zhou

School of Materials Science and Engineering, Xiangtan University, Hunan 411105, China

Abstract: Aero-engine is an important symbol of the country's core competitiveness. The turbine blade which suffers from the most demanding environment is the core component of aero-engine. The thermal barrier coating (TBCs) is an indispensable thermal protection material for turbine blades. However, the delamination of TBCs is a huge bottleneck of their security application. The analysis of delamination mechanism and reliability assessment technology is an inevitable way to realize the safety application of TBCs. However, the performance assessment technology, the theoretical model of thermo-chemo-mechanical coupled failure and the equivalent acceleration simulation with testing technology of extreme environment are great challenges. In order to overcome the limitations which adhesive-stretching method and bending method cannot obtain the intrinsic mechanical properties of TBCs, a characterization theory of mechanical properties considering the strength and toughness of the TBCs was proposed. The measurement method taking fracture energy as the dominant parameter was developed. The characterization method and test device for the key mechanical properties of TBCs were invented. A real-time characterization method for cracking, oxidation, deformation and other critical damage parameters in the failure process of TBCs under 1600 °C high temperature service environment was established. Based on thermo-chemo-mechanical coupled constitutive model of TBCs and numerical calculation method, the failure process of the TBCs under typical loads (eg. interface oxidation, thermal shock, erosion, CMAS) were reproduced. A device which can real-time detect the failure process of TBCs and simulate the service environment of TBCs, such as high temperature, erosion and CMAS corrosion, was constructed autonomously. Moreover, a reliability prediction model and numerical calculation method for TBCs considering the dispersivity of material and service environment was developed. Based on this model and calculation method, the failure probability of TBCs induced by high temperature erosion and oxidation was predicted. The dominant parameters affecting the reliability of TBCs were also founded.

热障涂层破坏理论与可靠性评价

周益春

湘潭大学，材料科学与工程学院，湖南

摘要：航空发动机是体现国家核心竞争力的重要标志，承温、承载最苛刻的涡轮叶片是最核心部件，热障涂层是涡轮叶片必不可少的热防护材料，涂层剥落是巨大瓶颈。剥落机制与可靠性的分析评价技术，是实现热障涂层安全应用的必然途径，但性能评价技术、热力化耦合失效的理论模型与极端环境的等效加速模拟与测试技术是巨大挑战。论文针对传统强度测量方法无法得到涂层本征力学性能的局限，协同考虑强度与韧性提出了涂层力学性能的表征理论，建立了以断裂能为主控参数的测量原理，发明了热障涂层关键力学性能的表征方法与测试装置。建立了1600°C高温复杂服役环境下热障涂层失效过程中裂纹、氧化、变形等关键损伤参量的实时表征方法，结合热障涂层热力化耦合的本构模型与数值计算方法，从实验和理论两个方面系统研究了热障涂层界面氧化、热冲击、冲蚀、CMAS等典型载荷作用下涂层的失效过程。自主研制了 “高温、冲蚀、CMAS腐蚀”服役环境模拟与涂层失效在线检测的试验装置，并建立一种考虑材料、服役环境分散性的热障涂层可靠性预测模型与数值计算方法，实现了高温冲蚀、高温氧化机制诱导下涂层失效概率的预测与关键因素分析。