涡轮叶片热障涂层在CMAS 环境下的失效分析

对于多台份某型发动机在试车后出现的带热障涂层涡轮叶片表面附着较多环境沉积物CMAS进而导致热障涂层脱落 失效的故障，通过宏观形貌观察、化学成分分析、微观结构分析等方法对CMAS分布规律、成分特征和失效模式进行了分析。结果 表明：CMAS沉积物在叶盆面较厚、叶背面较薄，靠近缘板处较厚、叶身中部位置较薄，进气边较厚、排气边较薄；厚度较薄处的附 着物颗粒细小、分布均匀，较厚处的附着物结构较疏松，大多呈块状不均匀分布；涡轮叶片热障涂层表面沉积物及气膜孔堵塞物的 成分以CMAS为主，同时还有中低温部件碰摩磨屑生成的Fe2O3、TiO2和NiO；由CMAS腐蚀引发的热障涂层失效模式主要有气膜孔 堵塞引发周围涂层烧结失效、涂层表面和内部应力失配、陶瓷层柱状晶被冲击撞断以及8YSZ热障涂层被溶解。

Failure Analysis of Thermal Barrier Coatings on Turbine Blade in CMAS Environment

The distribution law , components and failure mode of CMAS were analyzed by means of macroscopic morphology ohserva? tion , chemical composition analysis and microstrueture analysis for the faults which caused by environmental sediment CMAS that coverd on the surface of aeroengine turbine blades with thermal barrier coatings after many aeroengine tests. The result shows that CMAS is thicker on blade basin , near the blade platlorm and on the leading edge while thinner on blade back , the middle of blade and the trailing edge.The thick CMAS has exiguous particular and is well distributed, and the thin CMAS has loose structure and an uneven distribution.The deposits on the surface of thermal barrier coatings of turbine blades and the blockage of film holes are mainly CMAS, and there are also some Fe2O3, TiO2, and NiO which come from the debris produced by the friction of the medium and low temperature parts.The main failure modes of TBCs caused by CMAS are film holes plugged which results in coating sintering , stress mismatch at the surface and inside of the coating ,the fracture of the columnar crystals caused by impact and the dissolution of 8YSZ TBCs.