Numerical analyses of the residual stress and top coat cracking behavior in thermal barrier coatings under cyclic thermal loading. (1st June 2018)

• Record Type: Journal Article
• Authors: Jiang, Jishen; Wang, Weizhe; Zhao, Xiaofeng; Liu, Yingzheng; Cao, Zhaomin; Xiao, Ping
• Is Part Of: Engineering fracture mechanics. Volume 196(2018)
• Page Start: 191
• Page End: 205
• Publication Date: 2018-06-01
• Subjects: Thermal barrier coating -- Residual stress -- Failure -- Top coat crack -- Interfacial crack; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2018.04.031
• Languages: English
• ISSNs: 0013-7944

Abstract

Highlights: The interfacial asperity-induced TC cracking behavior in APS TBCs was studied. The TC crack initiated near the TGO and grew horizontally during thermal cycling. The creep and TGO growth greatly affected the length and path of TC crack. Both overly flat and rough interfaces shortened the TBC lifetime. The mutual interaction between TC and interfacial cracks accelerated TC failure. Abstract: Acting as one of the original cracks for interfacial delamination, the horizontal roughness-induced top coat crack plays an important role in the premature failure of the air plasma sprayed thermal barrier coating system. Thus, the residual stress and top coat cracking behavior in thermal barrier coatings under cyclic thermal loading were numerically investigated. The effects of thermally grown oxide swelling, creep, and interfacial roughness were taken into account. The arbitrary top coat cracking was modeled using the extended finite element method. In addition, the effect of the interfacial cracking on top coat cracking and their mutual interaction were investigated using the cohesive zone model. The results showed that the top coat crack initiated before thermal cycling due to large residual stress, the combination of the thermally grown oxide swelling and creep relaxation promoted crack propagation during the early periods, and the crack continued to grow with the thermally grown oxide thickening during the later periods. The initiation and propagation of the interfacial crack between the thermally grown oxide and bond coat accelerated the top coat cracking, and their mutual interaction led to premature interfacial delamination.