Characterisation of Cracks in Thermal Barrier Coatings using Impedance Spectroscopy

2008 ◽  
pp. 190-206
Author(s):  
Lifen Deng ◽  
Xiaofeng Zhao ◽  
Ping Xiao
Keyword(s):  
Impedance Spectroscopy ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings

NONDESTRUCTIVE IMPEDANCE SPECTROSCOPY EVALUATION OF THE BOND COAT OXIDATION IN THERMAL BARRIER COATINGS

2007 ◽  
Vol 14 (05) ◽  
pp. 935-943 ◽  
Author(s):  
L. YANG ◽  
Y. C. ZHOU ◽  
W. G. MAO ◽  
Q. X. LIU
Keyword(s):  
Impedance Spectroscopy ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Equivalent Circuit Model ◽  
Isothermal Oxidation ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Plasma Sprayed

In this paper, the impedance spectroscopy technique was employed to examine nondestructively the isothermal oxidation of air plasma sprayed (APS) thermal barrier coatings (TBCs) in air at 800°C. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) were also used to characterize the microstructure evolution of TBCs. After oxidation, the thermally grown oxide (TGO), which was mainly composed of alumina as confirmed by EDX, formed at the upper ceramic coat/bond coat interface, the lower bond coat/substrate interface, and the bond coat. Impedance diagrams obtained from impedance measurements at room temperature were analyzed according to the equivalent circuit model proposed for the TBCs. Various observed electrical responses relating to the growth of oxides and the sintering of YSZ were explained by simulating the impedance spectra of the TBCs.

Non-Destructive Characterisation of Thermal Barrier Coatings Using Impedance Spectroscopy

2000 ◽  
Vol 645 ◽  
Author(s):  
Junfa Mei ◽  
Xin Wang ◽  
Ping Xiao
Keyword(s):  
Electrical Properties ◽  
Impedance Spectroscopy ◽  
Oxide Layer ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Thermal Treatments ◽  
Barrier Coatings ◽  
Non Destructive ◽  
Clear Change ◽  
Composition Changes

ABSTRACTImpedance spectroscopy (IS) has been used to characterise the degradation of thermal barrier coatings (TBCs) due to thermal treatments at 1100°C for a period up to 200 hrs. The growth of the oxide layer at the yttria stabilised zirconia (YSZ)/bond coat interface in TBCs can be examined by measuring the impedance diagrams. From the analysis of the impedance diagrams of TBCs, the electrical properties of YSZ were found to be nearly constant during the thermal treatments, indicating there was little change in the microstructure and composition of YSZ. However, there was a clear change in the electrical properties of the oxide layer in the TBCs after thermal treatments, suggesting both microstructural and composition changes occurred in the oxide layer. These studies indicate that the IS is a very useful method in non-destructive characterisation of the degradation of TBCs.

The Impedance Spectroscopy Study of the Oxides Layer in Thermal Barrier Coatings

2018 ◽  
Vol 281 ◽  
pp. 510-515
Author(s):  
Zi Yuan Wang ◽  
Min Wang ◽  
Ya Jie Yuan ◽  
Wei Pan
Keyword(s):  
Impedance Spectroscopy ◽  
Thermal Barrier Coatings ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Relaxation Processes ◽  
Impedance Spectra ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Different Temperatures ◽  
Plasma Sprayed

Air-plasma-sprayed (APS) thermal barrier coatings (TBCs) were oxidized in air at different temperatures for 1000h and sequentially investigated by impedance spectroscopy (IS) and scanning electron microscopy (SEM). After oxidation at temperatures higher than 900°C, a thermally grown oxide (TGO) layer was formed at the bond coat/topcoat interface in TBCs. The impedance spectra of oxidized TBCs typically contains two relaxation processes that stem from the yttria-stabilized zirconia (YSZ) topcoat of TBCs and the TGO layer. The TGO resistivity that obtained by simulating the impedance spectra increased with the increasing of annealing temperature, demonstrating the growth and the densification of TGO layer.

scholarly journals Error and modification in thermal barrier coatings measurement using impedance spectroscopy

2017 ◽  
Vol 43 (6) ◽  
pp. 4976-4983 ◽  
Author(s):  
L. Yang ◽  
W. Zhu ◽  
C.F. Li ◽  
Y.C. Zhou ◽  
N.G. Wang ◽  
...  
Keyword(s):  
Impedance Spectroscopy ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
Barrier Coatings
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