Influence of Bond-coat Vacuum-annealing on the Lifetime of EB-PVD TBCs

LIU He, LI Shuai, YU Chun-tang, JIANG Cheng-yang, BAO Ze-bin, ZHU Sheng-long, WANG Fu-hui

Surface Technology ›› 2020, Vol. 49 ›› Issue (1) : 35-40.

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Surface Technology ›› 2020, Vol. 49 ›› Issue (1) : 35-40. DOI: 10.16490/j.cnki.issn.1001-3660.2020.01.004
Special Topic—High Temperature Corrosion and Protection

Influence of Bond-coat Vacuum-annealing on the Lifetime of EB-PVD TBCs

  • LIU He1, LI Shuai1, YU Chun-tang1, JIANG Cheng-yang2, WANG Fu-hui2, BAO Ze-bin3, ZHU Sheng-long3
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Abstract

The work aims to investigate the influence of bond-coat vacuum-annealing treatment on the service performance of thermal barrier coating under thermal cycle. Pt-modified nickel aluminide (PtAl) bond-coat by vapor phase aluminizing (VPA) and yttria stabilized zirconia (YSZ) top-coat by electron beam vapor physical deposition (EB-PVD) were sequentially deposited to a second-generation Ni-base superalloy to construct a thermal barrier coating system. The thermal cycle test was carried out in a cycling oxidation furnace which could automatically rise and fall at 1100 ℃. Net weight of the coating samples was measured by a high accuracy electronic balance and the mass change curves were drawn. Spallation tendency of ceramic topcoat was observed by macroscopic photographing. A field-emission scanning electron microscope was utilized to observe the cross-sectional morphology of coating samples in the as-received and thermally-cycled states. Compared with TBCs without pre-annealing treatment under vacuum, the oxidation resistance and thermal cycling performance of the annealed TBC samples were greatly increased, resulting in a doubled lifetime in the cyclic oxidation test and ceramic topcoat was well combined with the thermally grown oxide film. The ceramic topcoat on the surface of platinum-aluminum coating without pre-annealing treatment under vacuum had obvious spallation, and the quality of thermally grown oxide film was poor, resulting in obvious cracks. Notable spallation of ceramic topcoat occurred on the surface of normal TBC samples. Vacuum annealing treatment can make the surface of the platinum-aluminum coating smoother, the low-defect oxide film generated in the high-temperature oxidation process has better quality, the bonding force between the ceramic topcoat and the bond coating is stronger, and the service performance and service life of the thermal barrier coating system are effectively improved.

Key words

thermal barrier coatings; PtAl coating; cyclic oxidation; thermally grown oxide film

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LIU He, LI Shuai, YU Chun-tang, JIANG Cheng-yang, BAO Ze-bin, ZHU Sheng-long, WANG Fu-hui. Influence of Bond-coat Vacuum-annealing on the Lifetime of EB-PVD TBCs[J]. Surface Technology. 2020, 49(1): 35-40

Funding

Supported by General Program of National Natural Science Foundation of China (51671202) and the ‘Liaoning Baiqianwan Talents’ Program (201701)
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