等离子涂层热疲劳失效模式及失效机理研究

开展了等离子涂层构件热疲劳实验研究,对失效过程及失效模式进行考察,分析了对失效起主导作用的应力分量.针对陶瓷层材料引入粘塑性本构模型,对涂层的热疲劳进行数值模拟研究.分析表明,氧化层厚度为2 μm时,陶瓷层波峰位置容易萌生Ⅰ型横向裂纹,界面中部偏上位置容易萌生Ⅱ型横向裂纹;氧化层厚度为8 μm时,陶瓷层内部法向应力主导横向裂纹的扩展;不同厚度的氧化层内部将形成较高的应变能密度.给出了等离子涂层内部裂纹形成过程及机理. 

Study of failure mode and failure mechanisms on thermal fatigue of plasma sprayed thermal barrier coatings

Thermal fatigue test was conducted to study the failure process and failure mode of the plasma sprayed thermal barrier coating structures.The controlling factors for failure were also analyzed.Aviscoplastic constitutive model was introduced for the ceramic coat.Moreover,the thermal fatigue behavior of the coating layer was studied numerically.The analysis indicates that: mode Ⅰ crack is easily initiated at the peak position,and mode Ⅱ crack at above middle position of interfaces when TGO(thermaly growth oxides) thickness is 2 μm;the extension of transverse crack is dominated by normal stress when TGOthickness is 8 μm;high strain energy density is formed within TGOof different thickness.The process and mechanisms of crack coalescence within PS-TBC(plasma sprayed thermal grown oxides) were presented.