对电子束物理气相沉积(EB-PVD)双层结构热障涂层在热循环过程中形成的陶瓷层垂直裂纹对涂层失效模式的影响进行了研究. 结果表明, 陶瓷层表面垂直裂纹出现在热循环初期，但并未造成涂层的早期剥落; 随着热循环次数增加，垂直裂纹网格变密. 有限元计算表明，垂直裂纹的形成在试样中部产生了类似于试样边缘的剪应力集中效应. 经过长时间热循环后，当陶瓷层等轴晶区的强度或者热氧化生长层(TGO)的强度小于边缘效应产生的剪应力时，涂层在试样的中部以垂直裂纹网格形状发生剥落失效.
The influence of surface vertical cracks in YSZ coating on the failure mechanism of thermal barrier coatings prepared by electron beam physical vapor deposition (EB-PVD) during thermal cycling was studied. The vertical cracks occurred at the initial stage of thermal cycling testing but did not directly cause the spallation of TBC. The mesh density of vertical cracks increased following thermal cycles. Calculation by finite elements analysis showed that a larger shear stress was generated by the formation of the vertical cracks just like what in the edge of the specimen. After thermal cycling testing, when the strength of equiaxial grain regions or thermally grown oxidation layer became lower than the shear stress, the spallation occurred along the vertical crack network.
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