放射光高エネルギーX線による遮熱コーティングのはく離応力の評価

概要

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A new hybrid method is proposed to estimate the spalling stress normal to the interface in thermal barrier coating. As the X-ray energy becomes higher, the penetration depth gets deeper. The in-plane stress, σ_1, is measured by the conventional X-ray with the low energy, and the out-of-plane stress, σ_1-σ_3, is measured by the synchrotron X-ray with high energy. The spalling stress, σ_3, can be estimated from two measurements obtained by the conventional and the synchrotron X-ray methods. The bond coating of NiCoCrAlY with a thickness of 0.2mm was made by plasma spraying on a Ni super-alloy substrate, and the ZrO_2 top coating with a thickness of 0.2mm was plasma sprayed on the bond coating. The distribution of the in-plane residual stresses, σ_1, in the top coating was measured with characteristic X-rays Cr-Kα by repeating the measurements after successive removal of the surface layer. The residual stresses, σ_1-σ_3, were measured by the synchrotron X-rays with 73 keV. The spalling stress was estimated from the stresses measured by the two methods. The spalling stress, σ_3, was small tensile beneath the surface of the top coat but increased to 75 MPa near the interface between the top and bond coatings. A high tensile stress near the interface may induce the delamination of coatings.
社団法人日本機械学会の論文
2004-05-25