Study on Eddy-current Nondestructive Testing Method of the Double-layers Conductive Coating Thickness

doi:10.3901/JME.2017.14.114

Abstract

Abstract: The multiple-layered coating structure can significantly improve the heat resistance, wear resistance and corrosion resistance of the substrate material and therefore is applied widely in aerospace, petroleum and chemicals, and shipbuilding fields. The coating thickness plays key role in improving the substrate material performances. An eddy current nondestructive approach is presented to measure the coating thickness of the multiple-layered conductive coating structure. Above all, the interactions between the different layer thickness and the interaction of the coating thickness and coating conductivity on the detection signal are investigated by using numerical and experimental study. Thereafter, an approach to detect the coating thickness is proposed based on the decoupling algorithm, which is verified by the experiment. The experiment results indicate that the calibration values of coating thickness and those detected from the experiment agree well within the relative error of 10%. This approach can be extended further to the coating thickness measurement for the three-layered structure or four-layered structure.

Key words: decoupling algorithm, eddy current testing, multi-frequency excitation, multiple-layered conductive coating thickness

CLC Number:

TP391
TP206

GAO Kuanhou, YU Yating, YANG Jiao, SHEN Pengcheng. Study on Eddy-current Nondestructive Testing Method of the Double-layers Conductive Coating Thickness[J]. Journal of Mechanical Engineering, 2017, 53(14): 114-119.

References

[1] 宋国荣,吕炎,谭博涛,等. 薄板涂层结构镍镀层声学特征检测与弹性常数反演表征方法研究[J]. 机械工程学报,2014,50(4):11-12. SONG Guorong,LÜ Yan,TAN Botao,et al. Research on measurement of acoustic characteristics of nickel-coating plate and inversion method of elastic constants[J]. Journal of Mechanical Engineering,2014,50(4):11-12.
[2] 何存富,杨玉娥,杨申,等. 毫米波检测热障涂层缺陷的方法研究[J]. 机械工程学报,2013,49(20):16-17. HE Cunfu,YANG Yue,YANG Shen,et al. Feasibility study on defects detection of thermal barrier coatings using millimeter wave[J]. Journal of Mechanical Engineering,2014,49(20):16-17.
[3] LI Yong,CHEN Zhenmao,MAO Ying,et al. Quantitative evaluation of thermal barrier coating based on eddy current technique[J]. NDT & E International,2012,50:29-35.
[4] 冯驰, 滑翔. 红外热波技术在涡轮叶片涂层检测上的应用[J]. 应用科技,2015,45(1):15-16. FENG Chi,HUA Xiang. Applications of the infrared thermal wave technology in thermal barrier coating testing[J]. Applied Science and Technology,2015,45(1):15-16.
[5] CLARKE D R,PHILLPOT S R. Thermal barrier coating materials[J]. Materials Today,2005,8(6):22-24.
[6] 李达,李勇,闫贝,等. 航空发动机叶片热障涂层厚度的无损定量评估[J]. 空军工程大学学报,2015,16(6):22-25. LI Da,LI Yong,YAN Bei,et al. Quantitative non-destructive evaluation of thermal barrier coatings of aero-engine blades[J]. Journal of Air Force Engineering University,2015,16(6):22-25.
[7] YU Yating,GUAN Jia,Investigation of signal features of pulse eddy current testing technique by experiment[J]. Insight,2013,55(9):487-492.
[8] 张荣华,刘珊,张牧,等. 基于空间分布熵的电磁脉冲涡流无损检测方法[J]. 仪器仪表学报,2015,36(4):804-805. ZHANG Ronghua,LIU Shan,ZHANG Mu,et al. Pulse eddy current nondestructive testing method based on the spatical distribution entropy[J]. Chinese Journal of Scientific Instrument,2015,36(4):804-805.
[9] LI Yong,TIAN Guiyun,SIMM A. Fast analytical modeling for pulse eddy current evaluation[J]. NDT&E International,2008,41(6):477-483.
[10] TIAN Guiyun,SOPHIAN A,TAYLOR D,et al. Pulse eddy current system for dynamic inspection of defects[J] Insight,2004,46(5):256-259.
[11] YANG Hungchi,TAI Chengchi. Pulse eddy current measurement of a conducting coating on a magnetic metal plate[J]. Measurement Science and Technology,2002,13(8):1239-1265.
[12] ROPER F. A high-frequency eddy current method for the thickness measurement on thin metallic foils using ferrite-core transmission systems[J]. NDT&E International,2000,33(3):163-172.
[13] 康学福,陈立晶,王奔,等. 基于脉冲涡流信号的金属膜厚测量[J]. 机电工程,2012,29(1):4-7. KANG Xuefu,CHEN Lijin,WANG Ben,et al. Thickness measurement of metallic coating from pulse eddy-current signals[J]. Journal of Mechanical & Electrical Engineering,2012,29(1):4-7.
[14] LIU Lijuan,YU Yating,DAI Yuehong,et al. An approach to thin coating thickness measurement by eddy current testing technique[C]//Far East Nondestructive Testing new Technology and Application Forum,May 22-26,2012,Hefei,China,2012:317-320.
[15] 范孟豹,黄平捷,叶波,等. 多层导电结构厚度电涡流检测解析模型[J]. 中国电机工程学报,2008,28(27):142-147. FAN Mengbao,HUANG Pingjie,YE Bo,et al. Analytical model for eddy current testing of thickness of multi-layered structures and experimental verification[J]. Procedings of CSEE,2008,28(27):142-147.
[16] ZHANG Dejun,YU Yating,LAI Chao,et al. Thickness measurement of multi-layer conductive coatings using multifrequency eddy current technique[J]. Nondesttructive Testing and Evaluation,2016,31(3):191-208.
[17] 雷银照. 时谐电磁场解析方法[M]. 北京:科学出版社,2000. LEI Yinzhao. Analytic method of time harmonic electromagnetic field[M]. Beijing:Science Press,2000.
[18] 于亚婷,杜平安,廖雅琴. 线圈形状及几何参数对电涡流传感器性能的影响[J]. 仪器仪表学报,2007,28(6):1045-1050. YU Yating,DU Pingan,LIAO Yaqin. Study on effect of coil shape and geometric parameters on performance of eddy current sensor[J]. Chinese Journal of Scientific Instrument,2007,28(6):1045-1050.