サスペンションプラズマ溶射TBCの熱サイクル損傷機構の検討

抄録

In recent high-efficiency gas turbine combined cycle (GTCC) systems, thermal barrier coatings (TBCs) are indispensable for turbine blades due to the high temperature of the working combustion gas. Generally, the top coat (TC) of TBCs is deposited by atmospheric plasma spraying (APS) and electron beam physical vapor deposition (EB-PVD). On the other hand, the suspension plasma spraying (SPS) method, which enables microstructure control by using fine sprayed particles, has been studied for TBCs, because TC deposited by SPS have cauliflower-like columnar microstructure and are expected to have high thermal stress relaxation. In this study, we evaluated the thermal cycling characteristics of TBCs with different microstructures prepared by varying the column diameter of SPS. It reveals from the experimental results that the composite oxide growth, which causes a decrease in the thermal fatigue life, and the delamination crack propagation from the edge of interface are suppressed with decreasing the column diameter.