Estimation of Spalling Stress in Thermal Barrier Coating Using High Energy X-Rays from Synchrotron
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- ホウシャコウ コウエネルギー Xセン ニ ヨル シャネツ コーティング ノ ハクリ オウリョク ノ ヒョウカ
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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, σ1, is measured by the conventional X-ray with the low energy, and the out-of-plane stress, σ1-σ3, is measured by the synchrotron X-ray with high energy. The spalling stress, σ3, 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 0.2 mm was made by plasma spraying on a Ni super-alloy substrate, and the Zr02 top coating with a thickness of 0.2 mm was plasma sprayed on the bond coating. The distribution of the in-plane residual stresses, al, 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, σ1-σ3, 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, σ3, 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.
- TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A
TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series A 70 (693), 724-730, 2004
The Japan Society of Mechanical Engineers