Abstract
Model thermal-barrier coating (TBC) systems consisting of cast NiCrAlYsubstrates and electron-beam, physically vapor-deposited (EB–PVD)partially yttria-stabilized zirconia (PYSZ) coatings with three differentmicrostructures were tested in 1-hr cycles at 950°C under hot-corrosionconditions (sodium and sodium/potassium sulfates) likely to occur inbiomass-derived fuel-fired gas turbines. In contrast to conditionsinitiating Type I hot-corrosion attack, a modified test procedure wasused in this study where periodically salt-coated specimens were subjectedto an oxygen atmosphere while SOx was omitted, thus taking into account theessentially sulfur-free biomass fuel-combustion atmosphere. For comparison,similar tests were conducted on bare MCrAlY-type alloys. TBC failure byspallation of the PYSZ coating was observed between 300 and 500 1-hrcycles. Irrespective of PYSZ microstructure and deposit chemistry, failurewas primarily induced by crack formation and propagation within thevoluminous oxide scale formed as a result of hot-corrosion attack of themetal, rather than degradation of the ceramic layer. Since the major attackmode of the TBC seemed to be hot corrosion of the bond coat, this paperhighlights degradation mechanisms and microstructures of uncoated bond-coatcompositions. On the basis of the present results, implications of thefailure mode of EB–PVD PYSZ on in-service components are discussed.
Similar content being viewed by others
REFERENCES
H. E. Eaton, N. S. Bornstein, and J. T. DeMasi-Marcin, Proc. Internat. Gas Turbine Aeroengine Congr. Exhibition, ASME, Paper 96-GT-283 (1996).
G. W. Goward, Surf. Coat. Technol. 108, 73 (1998).
C. Leyens, I. G. Wright, and B. A. Pint, in Elevated Temperature Coatings: Science and Technology III, J. M. Hampikian and N. B. Dahotre, eds. (TMS, Warrendale, Pennsylvania, 1999), pp. 79–90
T. N. Rhys-Jones and F. C. Toriz, High Temp. Technol. 7, 73 (1989).
R. L. Jones, Mater. at High Temp. 9, 228 (1991).
R. L. Jones, Experiences in Seeking Stabilizers for Zirconia Having Hot Corrosion Resistance and High Temperature Tetragonal (t‱) Stability, NRL/MR/6170-96-7841 (1996).
N. S. Bornstein, JOM 48, 37 (1996).
N. S. Bornstein and W. P. Allen, Mater. Sci. Forum 251–254, 127 (1997).
C. Leyens, I. G. Wright, and B. A. Pint, Oxid. Met. 54, 255 (2000).
J. Stringer, Hot Corrosion in Gas Turbines, Metals and Ceramics Information Center, MCIC Report 72–08 (1972).
D. A. Shores and K. L. Luthra, Fundamentals of High-Temperature Corrosion (Academic Press, New York, 1992).
M. A. DeCrescente and N. S. Bornstein, Corrosion 24, 127 (1968).
J. A. Goebel, F. S. Pettit, and G. W. Goward, Metall. Trans. 4, 261 (1973).
R. A. Rapp and Y. S. Zhang, JOM 12, 47 (1994).
M. F. Trubelja, D. M. Nissley, N. S. Bornstein, and J. T. D. Marcin, Proc. Advan. Turbine Systems Annu. Program Rev. Meet. U.S. Department of Energy, Washington, DC (1997).
C. Leyens, U. Schulz, B. A. Pint, and I. G. Wright, Surf. Coat. Technol. 120-121, 68 (1999).
F. C. Toriz, A. B. Thakker, and S. K. Gupta, Proc. Intern. Gas Turbine Aeroengine Congr., ASME, Paper 88-GT-279 (1988).
M. P. Borom, C. A. Johnson, and L. A. Peluso, Surf. Coat. Technol. 87-88, 116 (1996).
I. G. Wright, C. Leyens, and B. A. Pint, Proc. Internat. Gas Turbine Aeroengine Congr., ASME (2000), pp. 2000-GT-19, New York.
D. K. Gupta and D. S. Duvall, in Superalloys 1984, M. Gellet al., eds. (TMS, Warrendale, Pennsylvania, 1984), pp. 711–720.
K. Fritscher, C. Leyens, U. Schulz, H.-J. Rätzer-Scheibe, M. Peters, and W. A. Kaysser, Proc. 3rd Internat. Conf., Microsc. Oxidation, S. B. Newcomb and J. A. Little, eds. (The Institute of Materials, London, 1997), pp. 352–365.
D. L. Deadmore and C. E. Lowell, Effects of Impurities in Coal-Derived Liquids on Accelerated Hot Corrosion of Superalloys, DOE/NASA 2593/13 (1980).
C. Leyens, I. G. Wright, B. A. Pint, and P. F. Tortorelli, in Cyclic Oxidation of High Temperature Materials, M. Schütze and W. J. Quadakkers, eds. (The Institute of Materials, London), pp. 169–186.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Leyens, C., Wright, I.G. & Pint, B.A. Hot Corrosion of an EB-PVD Thermal-Barrier Coating System at 950°C. Oxidation of Metals 54, 401–424 (2000). https://doi.org/10.1023/A:1004634400479
Issue Date:
DOI: https://doi.org/10.1023/A:1004634400479