Microstructural Evolution of Durable Thermal Barrier Coatings with Hf and/or Y Modified CMSX-4TM Superalloy Substrates

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Thermal cyclic lifetime and microstructural degradation of thermal barrier coatings (TBCs) with (Ni,Pt)Al bond coat and Hf- and/or Y-modified CSMX-4 superalloy substrates were examined. Thermal cyclic lifetime of TBCs was measured using a furnace thermal cycle test that consisted of 10-minute heat-up, 50-minute dwell at 1135°C, and 10-minute forced-air-quench. TBC lifetime was observed to improve from 600 cycles to over 3200 cycles with appropriate Hf- and/or Y-alloying of CMSX-4 superalloys. This significant improvement in TBC lifetime is the highest reported lifetime in literature with similar testing parameters. Cross-sectional microstructure of TBC specimens were examined by scanning electron microscopy (SEM) after the spallation failure. While undulation of TGO/bond coat interface (e.g., rumpling and racheting) was observed to be main damage mechanisms for TBCs on baseline CMSX-4, the same interface remained relatively flat for durable TBCs on Hf- and/or Y-modified CSMX-4. The parabolic growth constant of the TGO scale was slightly lower for TBCs with Hfand/ or Y-modified CSMX-4.

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Periodical:

Materials Science Forum (Volumes 539-543)

Main Theme:

Edited by:

T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran

Pages:

1206-1211

DOI:

10.4028/www.scientific.net/MSF.539-543.1206

Citation:

J. Liu et al., "Microstructural Evolution of Durable Thermal Barrier Coatings with Hf and/or Y Modified CMSX-4TM Superalloy Substrates", Materials Science Forum, Vols. 539-543, pp. 1206-1211, 2007

Online since:

March 2007

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$35.00

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