Reaction Mechanism and Thermal Insulation Property of Al-deposited 7YSZ Thermal Barrier Coating

To increase the performance and efficiency of thermal barrier coating (TBC), it is important to improve the thermal insulation property. In this work, a columnar Al film was deposited at the top of 7 wt% yttria-stabilized zirconia (7YSZ) TBC by magnetron sputtering. A vacuum heat treatment was then carried out to improve the insulation property of Al-deposited TBC. Reaction mechanism of Al-ZrO2 system in Al-deposited TBC was studied by differential thermal analysis (DTA). The phase structures of the as-sprayed TBC, the Al-deposited and vacuum-treated TBC were characterized. The microstructure evolution of Al-deposited TBC was illustrated after vacuum heat treatment. And the insulation property of the as-sprayed TBC and treated TBC was compared. The results show that a multi-scaled layer, consisting of micron/nano structured α-Al2O3 and Al3Zr grain was in situ synthesized at the top of 7YSZ coating via vacuum heat treatment. The TBC with the multi-scaled overlay has better insulation property than the as-sprayed TBC.