Thermal shock behavior of 8YSZ and double-ceramic-layer La₂Zr₂O₇/8YSZ thermal barrier coatings fabricated by atmospheric plasma spraying

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• 作者：L. Wang^a ; ^b ; ^{glacier_siccas@126.com} ; ^{glacier_hit@126.com} ; Y. Wang^a ; ^{wangyou@hit.edu.cn} ; X.G. Sun^a ; ^c ; J.Q. He^a ; Z.Y. Pan^a ; C.H. Wang^a ; ^d
• 关键词：C. Thermal shock resistance ; Atmospheric plasma spraying ; Thermal barrier coatings
• 刊名：Ceramics International
• 出版年：2012
• 期刊代码：13_02728842
• 类别：ms
• 出版时间：July, 2012
• 卷：38
• 期：5
• 页码：3595-3606
• 文件大小：3193 K

摘要

The single-ceramic-layer (SCL) 8YSZ (conventional and nanostructured 8YSZ) and double-ceramic-layer (DCL) La₂Zr₂O₇ (LZ)/8YSZ thermal barrier coatings (TBCs) were fabricated by plasma spraying on nickel-based superalloy substrates with NiCrAlY as the bond coat. The thermal shock behavior of the three as-sprayed TBCs at 1000 掳C and 1200 掳C was investigated. The results indicate that the thermal cycling lifetime of LZ/8YSZ TBCs is longer than that of SCL 8YSZ TBCs due to the fact that the DCL LZ/8YSZ TBCs further enhance the thermal insulation effect, improve the sintering resistance ability and relieve the thermal mismatch between the ceramic layer and the metallic layer at high temperature. The nanostructured 8YSZ has higher thermal shock resistance ability than that of the conventional 8YSZ TBC which is attributed to the lower tensile stress in plane and higher fracture toughness of the nanostructured 8YSZ layer. The pre-existed cracks in the surface propagate toward the interface vertically under the thermal activation. The nucleation and growth of the horizontal crack along the interface eventually lead to the failure of the coating. The crack propagation modes have been established, and the failure patterns of the three as-sprayed coatings during thermal shock have been discussed in detail.