Role of internal oxidation on the failure of air plasma sprayed thermal barrier coatings with a double-layered bond coat

SURFACE & COATINGS TECHNOLOGY

卷:319

Article

Zou, Zhonghua¹  Jia, Libing²  Yang, Lixia¹  Shan, Xiao¹  Luo, Lirong¹  Guo, Fangwei¹  Zhao, Xiaofeng¹  Xiao, Ping³ 

[1] Shanghai Jiao Tong Univ, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R China

[2] Siemens Ltd, Corp Technol, Gas Turbine Dev Ctr, Beijing, Peoples R China

[3] Univ Manchester, Sch Mat, Grosvenor St, Manchester M1 7HS, Lancs, England

关键词: Thermal barrier coating;    Bond coat;    Air plasma spray;    Internal oxidation;    Failure;   

DOI  :  10.1016/j.surfcoat.2017.04.026

来源: Elsevier

【 摘 要 】

Failure of air plasma sprayed (APS) thermal barrier coatings (TBCs) with a double-layered bond coat was investigated. The bond coat consists of a dense layer near the substrate side and a porous layer on the surface. Both were made of NiCoCrAlY alloy and deposited using high velocity oxygen-fuel technique. After thermal cycling, a large amount of internal oxides formed (up to 45% in volume fraction), introducing a significant volume expansion both in in-plane and perpendicular direction in the bond coat. However, the presence of the ceramic top coat can suppress the bond coat in-plane swelling thus lowering the internal oxidation rate. Compared with the fully dense bond coat, the interface roughness of the porous bond coat increases significantly when internal oxidation occurs. There is a strong correlation between the internal oxidation and the interface roughness. In addition, both the beneficial and detrimental effects of internal oxidation on TBC failure were discussed. It is proposed that a fully dense bond coat with a proper surface roughness should have a longer thermal cycling lifetime. (C) 2017 Elsevier B.V. All rights reserved.

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