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摘要
This article reviews previous studies on nondestructive evaluation of thermal barrier coatings (TBCs) using impedance spectroscopy (IS). IS or electrochemical impedance spectroscopy has been widely used to measure the electrical properties of materials and electrochemical behavior at electrode/electrolyte interfaces. TBCs, which comprise metallic and ceramic multilayers, have been widely used in the hot section of aeroturbine engines to increase turbine efficiency and to extend the life of metallic components. Since 1999, IS has been developed to examine degradation of the TBCs as a nondestructive evaluation tool, which is critical for prediction of TBCs lifetime during service. IS has been used both at high temperature in dry environments and in aqueous solutions. Impedance spectra of TBCs reflect change in TBC thickness, porosity, cracks, sintering, and yttria-stabilized zirconia phase transformation. Meanwhile, impedance measurements indicate the thermally grown oxide growth and the failure in TBCs. In addition, the thermal conductivity of TBCs can be correlated to impedance measurement results.
- 出版日期2009
