Calcium-magnesium-alumina-silicate (CMAS) corrosion has been regarded as the most important factor that leads to the degradation of thermal barrier coatings (TBCs). The failure mechanism of TBCs attacked by CMAS corrosion in the actual service conditions is still not clear due to the lack of an environmental simulator and nondestructive testing techniques. To solve the above problems, a real-time acoustic emission method combined with infrared thermography are developed to investigate the failure mechanism of TBCs attacked by CMAS corrosion. The results show that the acoustic emission signal spectrum only depends on the failure mode of the TBCs, and five failure modes are identified: surface vertical cracks, sliding interfacial cracks, opening interfacial cracks, substrate deformation and noise. The lifetime of TBCs attacked by CMAS corrosion is 40 thermal shock cycles, which is nearly six times lower than that of TBCs without CMAS corrosion (350 cycles). Conclusions: The failure mechanism of the former is interlaminar cracking and delamination in the ceramic coating; while that for the latter is interfacial delamination in the vicinity of thermal growth oxide.

中文翻译：

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热冲击下 APS 热障涂层中 CMAS 腐蚀失效的实时检测

钙镁铝硅酸盐（CMAS）腐蚀被认为是导致热障涂层（TBCs）降解的最重要因素。由于缺乏环境模拟器和无损检测技术，TBCs在实际服役条件下遭受CMAS腐蚀的失效机制尚不清楚。为解决上述问题，开发了一种结合红外热成像的实时声发射方法，研究了 CMAS 腐蚀攻击 TBC 的失效机制。结果表明，声发射信号谱仅取决于TBCs的失效模式，识别出五种失效模式：表面垂直裂纹、滑动界面裂纹、张开界面裂纹、基体变形和噪声。受到 CMAS 腐蚀的 TBCs 的寿命为 40 次热冲击循环，比没有受到 CMAS 腐蚀的 TBCs（350 次循环）低近 6 倍。结论：前者的失效机理为陶瓷涂层层间开裂、分层；而后者是热生长氧化物附近的界面分层。