Effect of Water Vapor on the Spallation of Thermal Barrier Coating Systems During Laboratory Cyclic Oxidation Testing
Tóm tắt
The effect of water and water vapor on the lifetime of Ni-based superalloy samples coated with a typical thermal barrier coating system—β-(Ni,Pt)Al bond coat and yttria stabilized zirconia (YSZ) top coat deposited by electron beam physical vapor deposition (EB-PVD) was studied. Samples were thermally cycled to 1,150 °C and subjected to a water-drop test in order to elucidate the effect of water vapor on thermal barrier coating (TBC) spallation. It was shown that the addition of water promotes spallation of TBC samples after a given number of cycles at 1,150 °C. This threshold was found to be equal to 170 cycles for the present system. Systems based on β-NiAl bond coat or on Pt-rich γ/γ′ bond coat were also sensitive to the water-drop test. Moreover, it was shown that water vapor in ambient air after minutes or hours at room temperature, promotes also TBC spallation once the critical number of cycles has been reached. This desktop spalling (DTS) can be prevented by locking up the cycled samples in a dry atmosphere box. These results for TBC systems confirm and document Smialek’s theory about DTS and moisture induced delayed spalling (MIDS) being the same phenomenon. Finally, the mechanisms implying hydrogen embrittlement or surface tension modifications are discussed.
Tài liệu tham khảo
A. G. Evans, D. R. Mumm, J. W. Hutchinson, G. H. Meier, and F. S. Pettit, Progress in Materials Science 46, 505 (2001).
J. L. Smialek, Report NASA/TM—2005-214030 (2005), pp. 36.
B. A. Pint, J. A. Haynes, Y. Zhang, K. L. More, and I. G. Wright, Surface & Coating Technology 201, 3852 (2006).
M. Rudolphi, D. Renusch, and M. Schütze, Scripta Materialia 59, 255 (2008).
J. L. Smialek, D. Zhu, and M. D. Cuy, Scripta Materialia 59, 67 (2008).
E. P. George, C. T. Liu, H. Lin, and D. P. Pope, Materials Science and Engineering A192/193, 277 (1995).
J. L. Smialek, Materials Science Forum 595–598, 191 (2008).
R. T. Wu, K. Kawagishi, H. Harada, and R. C. Reed, Acta Materialia 56, 3622 (2008).
J. L. Smialek, Report NASA CP 10193, 1 (1997).
R. Janakiraman, G. H. Meier, and F. S. Pettit, Metallurgical and Materials Transactions A 30A, 2905 (1999).
J. L. Smialek, JOM 1, 29 (2006).
C. T. Liu, C. L. Fu, E. P. George, and G. S. Painter, ISIJ International 31, 1192 (1991).
T. Takasugi, ISIJ International 143, 128 (2003).
Z.-Y. Deng, Y.-F. Liu, Y. Tanaka, J. Ye, and Y. Sakka, Journal of American Ceramic Society 88, 977 (2005).
Z.-Y. Deng, Y.-F. Liu, Y. Tanaka, H.-W. Zhang, J. Ye, and Y. Kagawa, Journal of American Ceramic Society 88, 2975 (2005).
Z.-Y. Deng, J. M. F. Ferreira, Y. Tanaka, and J. Ye, Journal of American Ceramic Society 90, 1521 (2007).
G. L. Chen and C. T. Liu, International Materials Reviews 46, 253 (2001).
D. Francois, A. Pineau, and A. Zaoui, Comportement mécanique des matériaux Tome 2: viscoplasticité, endommagement, rupture (2° Ed.), ed. Hermes-Lavoisier, (1993), pp. 496.
H.-E. Zschau, M. Dietrich, D. Renusch, M. Schütze, J. Meijer, and H.-W. Becker, Nuclear Instruments and Methods in Physics Research Section B 249, 2006 (381).
V. Sergo and D. R. Clarke, Journal of American Ceramic Society 81, 3237 (1998).
V. Tolpygo and D. R. Clarke, Materials Science and Engineering. A278, 142 (2000).
D. Renusch, H. Echsler, and M. Schuetze, Materials at High Temperature 21, 65 (2004).