Numerical study of residual stresses in environmental barrier coatings with random rough geometry interfaces. Issue 4 (15th February 2023)

• Record Type: Journal Article
• Authors: Du, Jinkang; Yu, Guoqiang; Jia, Yunfa; Liu, Chenyang; Sui, Zhengqing; Gao, Xiguang; Wang, Fang; Song, Yingdong
• Is Part Of: Ceramics international. Volume 49:Issue 4(2023)
• Page Start: 5748
• Page End: 5759
• Publication Date: 2023-02-15
• Subjects: Ceramic matrix composites -- Environmental barrier coating -- Surface roughness -- Thermally grown oxide; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2022.10.108
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: To clarify the role of the coating interface geometry and thermally grown oxide (TGO) layer in the failure of environmental barrier coatings (EBCs) and to further understand the cracking and spalling mechanisms of coatings, in this study, the thermomechanical properties of the multilayer coating system (Yb2 SiO5 /Yb2 Si2 O7 /Si), the morphology of the coating interface and the influence of the oxide layer on the local stresses during cooling were considered based on a random rough interface geometry model. The results showed that the rough geometry increased the magnitude of residual stresses at the interface and that the stress distribution away from the interface was less affected than the coating without roughness. The cracks on the outer surface of the Yb2 SiO5 layer initiate in the valley region and spread with a stress value independent of the TGO thickness, and this failure may occur by cracking under tensile stress. The overall stress intensity at the TOP/EBC interface was lower than that at the upper surface of the TOP layer. The presence of TGO increased the magnitude of residual stresses in the BC and EBC layers, which caused cracks at the TGO/BC and TGO/EBC interfaces to occur at opposite locations. The phase change of the TGO layer from β-cristobalite to α-cristobalite cause a rapid increase in the overall level of coating stress, which may be a direct factor in coating failure. The calculation results provide a theoretical basis for the coating design and manufacturing process.