使役环境涡轮叶片EB-PVD热障涂层失效机制

Failure Mechanism of EB-PVD Thermal Barrier Coating on Turbine Blades in Service Environment

摘要:

运用场发射扫描电镜、能量色散光谱仪和金相显微镜等测试表征手段，详细检查退役高温发动机涡轮叶片表面涂层残存状况，发现带气膜孔的高温发动机涡轮叶片经服役2000 h后，表面各部位EB-PVD涂层承受CMAS攻击、硬质物撞击和冷热应力冲击程度各异，导致退役叶片表面共存多种损伤．通过对这些损伤现象的分析，了解使役环境下叶片各部位的失效模式和失效机理．研究结果表明：叶棱为受CMAS攻击最严重处，同时也是受硬质点撞击最密集处，存在大面积涂层脱落；气膜孔周围的TBCs涂层受CMAS攻击发生本质性固化，受交变热应力和机械应力共同作用而呈规律性脱落；叶棱周围气膜孔表面（无论是叶背或是叶盆）均存在硬质物碾压划过叶片表面而压实CMAS，引起表面TBCs脱落的现象，同时在气膜孔内发现飞落的TBCs柱和CMAS块，从侧面反应对叶片表面造成实质性伤害的硬质物可能为脱落的TBCs柱或固化的CMAS块．

Abstract:

Using field emission scanning electron microscope， energy dispersive spectrometer and metallographic microscope and other test methods， the residual condition of the surface coating of the high-temperature turbine blade of the retired engine was examined in detail. ， the EB-PVD coating on various parts of the surface is subjected to different degrees of CMAS attack， hard material impact， and thermal stress impact， resulting in the coexistence of multiple damages on the surface of retired blades. Through analysis of these damage phenomena， the failure mode and failure mechanism of each part of the blade under the service environment are clarified. The research results show that the blade edge is the most severely attacked by CMAS， and it is also the most densely impacted by hard points， so there is a large area of ??coating peeling； Under the combined action of alternating thermal stress and mechanical stress， it falls off regularly； there are hard substances on the surface of the air film hole around the leaf edge （whether it is the back of the leaf or the leaf basin）， and the CMAS is compacted by rolling across the surface of the blade and compacting the CMAS. This causes the phenomenon of surface TBCs falling off. At the same time， flying TBCs pillars and CMAS blocks are found in the air film holes， reminding us from the side that the hard substances that cause substantial damage to the blade surface may be fallen TBCs pillars or solidified CMAS piece.