This work investigates the failure mechanism of an air plasma spraying(APS) thermal barrier coatings(TBCs) with various bond coat(BC) surface toughness under constant temperature loading condition. Results show that t...This work investigates the failure mechanism of an air plasma spraying(APS) thermal barrier coatings(TBCs) with various bond coat(BC) surface toughness under constant temperature loading condition. Results show that the increased BC surface roughness decreased the lifetime. Moreover, the relationship between the TGO depth and the lifetime can be well described by linear law.The failure mechanism of the TBCs samples was studied by cross-sectional morphologies observation and using the finite element method(FEM). Cracks in the TBCs samples with higher BC surface roughness are initiated from the defects on the BC caused by Al depletion in the BC layer. However, cracks in the samples of TBCs with lower BC surface roughness condition preferentially occur at the TC-TGO interface. This finding could be attributed to the high mismatch stresses in the TC-TGO interface.展开更多
This study investigated the damage evolution(i.e., formation of vertical cracks, transformation of vertical cracks to interfacial crack and delamination) of thermal barrier coating systems under tension by using exper...This study investigated the damage evolution(i.e., formation of vertical cracks, transformation of vertical cracks to interfacial crack and delamination) of thermal barrier coating systems under tension by using experimental and numerical methods.Experimental results revealed that the first transverse crack that was perpendicular to the load direction occurred when the strain of the top coat reached 0.5%. The full-scale strain of the top coat layer obtained by using the Digital Image Correlation technique indicated that surface cracks formed due to the coalescence of micro-cracks. Moreover, the results of the finite element method demonstrated that the vertical cracks initiated from the coating surface and extended through the thickness of the coatings. The density of the surface cracks was used as a damage evolution indicator such that numerical simulation could predict the cracking behaviour under tension loading. The results were consistent with those of the experimental study.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.51571010)the National Basic Research Program of China(Grant No.2015CB057400)the Hong Kong Scholar Program(Grant No.XJ2016040)
文摘This work investigates the failure mechanism of an air plasma spraying(APS) thermal barrier coatings(TBCs) with various bond coat(BC) surface toughness under constant temperature loading condition. Results show that the increased BC surface roughness decreased the lifetime. Moreover, the relationship between the TGO depth and the lifetime can be well described by linear law.The failure mechanism of the TBCs samples was studied by cross-sectional morphologies observation and using the finite element method(FEM). Cracks in the TBCs samples with higher BC surface roughness are initiated from the defects on the BC caused by Al depletion in the BC layer. However, cracks in the samples of TBCs with lower BC surface roughness condition preferentially occur at the TC-TGO interface. This finding could be attributed to the high mismatch stresses in the TC-TGO interface.
基金supported by the National Natural Science Foundation of China(Grant No.51571010)the National Basic Research Program of China(Grant No.2015CB057400)
文摘This study investigated the damage evolution(i.e., formation of vertical cracks, transformation of vertical cracks to interfacial crack and delamination) of thermal barrier coating systems under tension by using experimental and numerical methods.Experimental results revealed that the first transverse crack that was perpendicular to the load direction occurred when the strain of the top coat reached 0.5%. The full-scale strain of the top coat layer obtained by using the Digital Image Correlation technique indicated that surface cracks formed due to the coalescence of micro-cracks. Moreover, the results of the finite element method demonstrated that the vertical cracks initiated from the coating surface and extended through the thickness of the coatings. The density of the surface cracks was used as a damage evolution indicator such that numerical simulation could predict the cracking behaviour under tension loading. The results were consistent with those of the experimental study.
