3406 経年劣化したTBCにおけるインピーダンススペクトルの周波数応答解析(S16-2 遮熱コーティング(TBC)(2),S16 コーティング材料の皮膜特性とその評価)

抄録

To establish the fundamentals of the non-destructive evaluation by using impedance spectroscopy technique, the impedance of a degraded TBC and a stand-alone YSZ were measured using platinum electrodes at temperatures between 300℃ and 1000℃. The impedance spectra of the TBC show the response of the electrode reaction, the thermally grown oxide (TGO) and the YSZ grain in order of the frequency. The impedance of the TGO depends on the asymmetry of electrode and the substrate size. On the other hand, the impedance of the YSZ grain is independent of the asymmetry of electrode and the substrate size. Above 800℃, the contribution of the YSZ grain is negligible, because of very small impedance. The impedance of the electrode reaction is governed by the electrode reaction area and voltage drop caused by the TGO resistance. If the correlation between the TGO impedance and the substrate size was clarified, the TGO thickness could be evaluated quantitatively. The delamination of TBC at the YSZ/TGO interface can be detected by monitoring the impedance of the electrode reaction. Moreover, the degradation of the YSZ top coating can be evaluated by measuring the impedance of the YSZ grain at temperatures under 800℃.