Journal of the Korean Society for Nondestructive Testing (비파괴검사학회지)

The Korean Society for Nondestructive Testing (한국비파괴검사학회)
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Designing a Highly Sensitive Eddy Current Sensor for Evaluating Damage on Thermal Barrier Coating

열차폐코팅의 비파괴적 손상 평가를 위한 고감도 와전류 센서 설계

  • Received : 2016.04.04
  • Accepted : 2016.05.10
  • Published : 2016.06.30
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Abstract

A thermal barrier coating (TBC) has been widely applied to machine components working under high temperature as a thermal insulator owing to its critical financial and safety benefits to the industry. However, the nondestructive evaluation of TBC damage is not easy since sensing of the microscopic change that occurs on the TBC is required during an evaluation. We designed an eddy current probe for evaluating damage on a TBC based on the finite element method (FEM) and validated its performance through an experiment. An FEM analysis predicted the sensitivity of the probe, showing that impedance change increases as the TBC thermally degrades. In addition, the effect of the magnetic shield concentrating magnetic flux density was also observed. Finally, experimental validation showed good agreement with the simulation result.

열차폐코팅은 극한의 열환경에서 사용되는 기계요소를 고온으로부터 보호하기 위하여 널리 이용하는 코팅으로, 관련 산업의 경제적 이윤과 사용자 안전에 관련한 중요한 기술이다. 따라서 이런 열차폐코팅의 비파괴적 손상 평가는 그 중요성이 높이 평가되어 왔으나, 코팅 파쇄의 원인이 되는 내부의 미세한 조성 변화를 감지하기 위한 기술적 난제를 안고 있는 연구 주제이다. 본 논문은 열차폐코팅의 비파괴적 손상 평가를 위한 유한요소해석 기반 고감도 와전류 센서 설계 과정을 소개하고, 설계한 센서를 제작하여 진행한 성능 평가를 통해 설계 과정을 검증하였다. 와전류 센서의 성능을 예측하기 위하여 유한요소해석을 수행한 결과, 열차폐코팅의 손상 정도에 따른 센서의 임피던스가 증가와, 마그네틱 쉴드를 적용하였을 때 자속집속에 의한 검출능 향상을 관찰할 수 있었다. 또한 실제 실험결과와 비교를 통해 유한요소해석 결과를 검증하였다.

Keywords

References

  1. R. A. Miller, "History of thermal barrier coatings for gas turbine engines: Emphasizing NASA's Role from 1942 to 1990" (2009)
  2. H. Brodin, M. Jinnestrand, S. Johansson and S. Sjostrom, "Thermal barrier coating fatigue life assessment," Siemens AG (2006)
  3. A. Fahr, B. Roge and J. Thornton, "Detection of thermally grown oxides in thermal barrier coatings by nondestructive evaluation," Journal of Thermal Spray Technology, Vol. 15(1), pp. 46-52 (2006) https://doi.org/10.1361/105996306X92587
  4. Z. Ma, Y. Zhao, Z. Luo and L. Lin, "Ultrasonic characterization of thermally grown oxide in thermal barrier coating by reflection coefficient amplitude spectrum," Ultrasonics, Vol. 54(4), pp. 1005-1009 (2014) https://doi.org/10.1016/j.ultras.2013.11.012
  5. Y. Zhao, L. Lin, X. M. Li and M. K. Lei, "Simultaneous determination of the coating thickness and its longitudinal velocity by ultrasonic nondestructive method," NDT & E International, Vol. 43(7), pp. 579-85 (2010) https://doi.org/10.1016/j.ndteint.2010.06.001
  6. G. Ptaszek, P. Cawley, D. Almond and S. Pickering, "Transient thermography testing of unpainted thermal barrier coating (TBC) systems," NDT & E International, Vol. 59, pp. 48-56 (2013) https://doi.org/10.1016/j.ndteint.2013.05.001
  7. C. C. Cheng, C. V. Dodd and W. E. Deeds, "General analysis of probe coils near stratified conductors," International Journal of Nondestructive Testing, Vol. 3, pp. 109-130 (1971)
  8. Y. Li, T. Theodoulidis and G. Y. Tian, "Magnetic field-based eddy-current modeling for multilayered specimens. Magnetics," IEEE Transactions on Magnetics, Vol. 43(11), pp. 4010-4015 (2007) https://doi.org/10.1109/TMAG.2007.904930
  9. Q. Zhao, Q. Yu, Z. Qu, L. Si, X. Lu and Y. Meng, "Thickness measurement of nano-metallic film with electromagnetic sensor under large sensor-sample distance," Instrumentation and Measurement Technology Conference (I2MTC), pp. 1-4 (2011)
  10. R. Hughes, Y. Fan and S. Dixon, "Near electrical resonance signal enhancement (NERSE) in eddy-current crack detection," NDT & E International, Vol. 66, pp. 82-89 (2014) https://doi.org/10.1016/j.ndteint.2014.04.009
  11. G.-M. Javier, G.-G. Jamie, V.-S. Ernesto, "Nondestructive techniques based on eddy current testing," Sensors, Vol. 11(3), pp. 2525-2565 (2011) https://doi.org/10.3390/s110302525
  12. A. C. Karaoglanli, K. Ogawa and A. Turk and I. Ozdemir, "Thermal shock and cycling behavior of thermal barrier coatings (TBCs) used in gas turbines," Progress in Gas Turbine Performance, pp. 237-260 (2013)
  13. H. A. Sabbagh, E. H. Sabbagh, R. K. Murphy and J. Nyenhuis, "Assessing thermal barrier coatings by eddy-current inversion," Material Evaluation, Vol. 59(11), pp. 1307-1312 (2001)

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