APS法及びSPS法によって成膜されたYbTa₃O₉/YSZ-TBCの熱サイクル損傷挙動

抄録

Yttria stabilized zirconia thermal barrier coatings (YSZ-TBC) deposited by atmospheric plasma spraying (APS) are essential for advanced power generation gas turbines. On the other hand, the previous studies indicated that a suspension plasma sprayed TBC (SPS-TBC) with a columnar microstructure had superior thermal cycle fatigue resistance compared with the conventional APS-TBC. However, it requires improving the thermal shielding property in the SPS-TBC with a columnar microstructure. In this study, we proposed a novel composite TBC with two types of double top-coating layers consisting of YbTa₃O₉ (YTO) and YSZ: (a) columnar-SPS-YSZ/continuous-layer-APS-YTO, and (b) columnar-SPS-YSZ/columnar-SPS-YTO. Thermal cycle fatigue tests were conducted to investigate their damage behaviors. The experimental result indicated that the damage morphology due to thermal cycle fatigue depended on the coating microstructure. The result of the FEM analysis, which shows the former have a smaller strain concentration than the latter, indicates superior thermal strain accommodation. Hence, these results suggest that the combination of TBCs deposited with YSZ by SPS and YbTa₃O₉ by SPS has excellent thermal cycling resistance.