As a nondestructive testing technique,terahertz time-domain spectroscopy technology is commonly used to measure the thickness of ceramic coat in thermal barrier coatings(TBCs).However,the invisibility of ceramic/therm...As a nondestructive testing technique,terahertz time-domain spectroscopy technology is commonly used to measure the thickness of ceramic coat in thermal barrier coatings(TBCs).However,the invisibility of ceramic/thermally grown oxide(TGO)reflective wave leads to the measurement failure of natural growth TGO whose thickness is below 10μm in TBCs.To detect and monitor TGO in the emergence stage,a time of flight(TOF)improved TGO thickness measurement method is proposed.A simulative investigation on propagation characteristics of terahertz shows the linear relationship between TGO thickness and phase shift of feature wave.The accurate TOF increment could be acquired from wavelet soft threshold and cross-correlation function with negative effect reduction of environmental noise and system oscillation.Thus,the TGO thickness could be obtained efficiently from the TOF increment of the monitor area with different heating times.The averaged error of 1.61μm in experimental results demonstrates the highly accurate and robust measurement of the proposed method,making it attractive for condition monitoring and life prediction of TBCs.展开更多
基金the National Natural Science Foundation of China(Grant Nos.52275096,51905102)the Fujian Provincial Science and Technology Project,China(Grant No.2019I0004)+2 种基金the State Key Laboratory of Mechanical Systems and Vibration,China(Grant No.MSV-2018-07)the Shanghai Natural Sciences Fund,China(Grant No.18ZR1414200)the China Postdoctoral Science Foundation(Grant No.2019M662226).
文摘As a nondestructive testing technique,terahertz time-domain spectroscopy technology is commonly used to measure the thickness of ceramic coat in thermal barrier coatings(TBCs).However,the invisibility of ceramic/thermally grown oxide(TGO)reflective wave leads to the measurement failure of natural growth TGO whose thickness is below 10μm in TBCs.To detect and monitor TGO in the emergence stage,a time of flight(TOF)improved TGO thickness measurement method is proposed.A simulative investigation on propagation characteristics of terahertz shows the linear relationship between TGO thickness and phase shift of feature wave.The accurate TOF increment could be acquired from wavelet soft threshold and cross-correlation function with negative effect reduction of environmental noise and system oscillation.Thus,the TGO thickness could be obtained efficiently from the TOF increment of the monitor area with different heating times.The averaged error of 1.61μm in experimental results demonstrates the highly accurate and robust measurement of the proposed method,making it attractive for condition monitoring and life prediction of TBCs.
