Evaluation of Stress Relaxation Property of Columnar Thermal Barrier Coatings by High Temperature Resonance Method
Year: 2026
Type: article
Abstract: The durability of suspension plasma sprayed thermal barrier coatings (SPS-TBC) has been reported to have a longer lifespan than conventional plasma sprayed TBC (C-TBC). This is thought to be due to stress relaxation by the columnar microstructure. However, it is difficult to quantitatively evaluate the stress relaxation properties of the fragile SPS-TBCs, so their stress relaxation properties are not well understood. In this study, first, we evaluated the curvature history (stress history) and temperature history during thermal spraying, leading to evaluation for the stress relaxation characteristics during deposition process. It was found that instantaneous high tensile stress during first deposition on the substrate was observed in SPS-TBC, similarly to segmentation cracked TBC (S-TBC). It was indicated that the high tensile stress contributed to the formation of inter-columnar gap of SPS-TBC and crack structures of S-TBC. Next, the stress relaxation property of SPS-TBC was evaluated by our original technique using high temperature resonance method, which is a technique for evaluating the tangent modulus of the stress-strain relationship under thermal stress. In particular, focusing on the deposition temperature, we evaluated the morphology of columnar structure and the stress relaxation properties of the SPS-TBCs. It was found that at low deposition temperatures, porous and wide inter-columnar gaps were able to be obtained, and that the stress relaxation properties were superior. Furthermore, it was found that its excellent relaxation property was maintained after sintering caused by thermal aging. It was also found that the sintering of SPS-TBC was less likely to occur compared to C-TBC. It was concluded that the inter-columnar gaps/crack gaps play a significant role in these outstanding stress relaxation properties.
Institutions: Iwate University, Tocalo Co., Ltd. (Japan)
Language: English
Subfield: Surfaces, Coatings and Films
Field: Materials Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7213637646