【摘要】 采用电子束物理气相沉积法(EB-PVD)在定向凝固Ni基高温合金DZ125基体上制备了NiCoCrAlY粘结层和YSZ陶瓷层,研究了高温拉压环境下热障涂层的失效模式,并对其进行了有限元分析。实验结果表明,热障涂层的失效与仅受热载荷作用下的有很大不同,仅有热载荷作用下的热障涂层裂纹多萌生于热氧化层(TGO)内部,进而扩展引起热障涂层的失效。而高温拉压试验后热障涂层体系存在两种裂纹,分别萌生于TGO/粘结层界面和粘结层/扩散层界面附近。有限元模拟结果显示TGO/陶瓷层和TGO/粘结层处存在应力状态的转变和应力值的突变,径向应力的突变导致了界面分离现象的产生,而轴向应力的突变加速了垂直于界面裂纹的扩展,并导致了试样的最终断裂。更多还原

【Abstract】 Tension-compression tests at high temperature were carried out on the specimens made of Ni based superalloys (DZ125 alloy) coated with bond coating (NiCoCrAlY) and zirconia ceramic coating by electron beam-physical vapor deposition(EB-PVD). Failure of the thermal barrier coatings (TBC) was investigated. The test results show that the failure of TBCs occurred from the initiation and expansion of fracture in TGO,differing from under thermal loading alone. There are two kinds of fracture cracks: initiating from the TGO/bond coat interface and the bond coat/diffusion coat,respectively,resulting in the failure of specimens at last. From the simulation results by finite element analysis (FE),it can be conclude that there are abrupt changes of stress state and value near the interfaces of TGO/TBC and TGO/bond coats. The abrupt change of radial stress would result in the failure of TBCs from the spallation of interface. The abrupt change of axial stress would accelerate the extension of the microcracks perpendicular to the interface,resulting in the rupture of specimens.更多还原