Corrosion behavior of calcium-magnesium-alumino-silicate on (La,Gd)2Zr2O7/YSZ multilayer for thermal barrier coatings

Seung-Hyeon Kim; Toshio Osada; Kee-Sung Lee; Yoon-Suk Oh; Nobuo Nagashima; Byung-Koog Jang

Article Corrosion behavior of calcium-magnesium-alumino-silicate on (La,Gd)₂Zr₂O₇/YSZ multilayer for thermal barrier coatings

Seung-Hyeon Kim (National Institute for Materials Science) ; Toshio Osada (National Institute for Materials Science) ; Kee-Sung Lee ; Yoon-Suk Oh ; Nobuo Nagashima (National Institute for Materials Science) ; Byung-Koog Jang

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Seung-Hyeon Kim, Toshio Osada, Kee-Sung Lee, Yoon-Suk Oh, Nobuo Nagashima, Byung-Koog Jang. Corrosion behavior of calcium-magnesium-alumino-silicate on (La,Gd)₂Zr₂O₇/YSZ multilayer for thermal barrier coatings. Journal of the Ceramic Society of Japan. 2024, 132 (5), 23096.

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In this study, the high-temperature corrosion behavior was evaluated for (La,Gd)2Zr2O7 (LGZ) used as a promising thermal barrier coatings (TBCs) material. (La,Gd)2Zr2O7 + YSZ multilayer prepared from atmos pheric plasma spray (APS) were exposed to calcium-magnesium-alumino-silicate (CMAS) melt at 1300 °C for 2, 12, 48, and 100 h. Molten CMAS and (La,Gd)2Zr2O7 reacted to form reaction layer Ca2Gd8(SiO4)6O2 (apatite) at 1300 °C. The thickness of the reaction layer increased with increasing heat-treatment time. A correlation between the hardness and Young’s modulus relationship for the reaction layer of the coating was observed for the microstructure using nanoindentation. It was confirmed that the pores of the coating were reduced through the infiltration of molten CMAS in the initial stage of the corrosion reaction, and the hardness and Young’s modulus were increased due to densification. Fracture toughness increased with heat treatment time in both directions (in-plane and through-thickness). The fracture toughness in the in-plane direction is 0.19–0.23 MPa. On the other hand, the fracture resistance in the thickness direction was 0.87–1.26 MPa, which was higher than that in the in-plane direction. These results show that the crack propagates in the in-plane direction and causes TBC delamination.

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