Transmission Electron Microscopy of Isothermally Oxidized EB-PVD Thermal Barrier Coating on (Ni,Pt)Al Bondcoat

Abstract:

The growth and microstructure of the thermally grown oxide (TGO) underneath the electron beam physical vapor deposited (EB-PVD) yttria stabilized zirconia (YSZ) topcoat were examined after short-term isothermal oxidation (1100 °C, up to 50 hours) for the as-coated and gritblasted (Ni,Pt)Al bondcoats. Microstructural analysis was carried out by a high resolution scanning transmission electron microscope equipped with bright/dark field imaging, high angle annular dark field imaging, and nano-spot energy dispersive spectroscopy. Presence of mixed oxide zone (MOZ) and a continuous Al2O3 oxide zone (COZ) was observed on the thermal barrier coating (TBC) with the as-coated (Ni,Pt)Al bondcoat. However, on the TBC with grit-blasted bondcoat, only the continuous-columnar Al2O3 scale was observed. For the as-coated type bondcoat, numerous voids were observed near the interface between MOZ and COZ after isothermal oxidation. On the other hand, COZ showed parabolic growth without any formation of voids for the grit-blasted specimens.

• Periodical: Materials Science Forum (Volumes 486-487)
• Pages: 149-152
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.486-487.149
• Online since: June 2005
• Authors: Jai Won Byeon, S. Laxman, Yong Ho Sohn
• Keywords: Bond Coat Surface Preparation , Grit-Blasting, Isothermal Oxidation, TEM, Thermal Barrier Coating (TBC)

References

[1] B. A. Pint, J. R. Martin and L.W. Hobbs: Oxid. Met. Vol. 39 (1993), p.167.

[2] D. M. Lipkin and D.R. Clarke: Oxi. Met. Vol. 45 (1996), p.267.

[3] K. S. Murphy, K. L. More and M. J. Lance: Surf. Coat. Technol. Vol. 146-147 (2001), p.152.

[4] M. R. Brickey and J. L. Lee: Oxi. Met. Vol. 54 (2000), p.237.

[5] H.C. Chen, J. Heberlein and E. Pfender, Thin Solid Films Vol. 301 (1997), p.105.

[6] S. Laxman, B. Franke, B. W. Kempshall, Y. H. Sohn, L. A. Giannuzzi and K. S. Murphy: Surf. Coat. Technol. Vol. 177-178 (2004), p.121.

[7] N. M. Yanar, M. J. Stiger, M. Maris-Sida, F. S. Pettie and G. H. Meier: Key Eng. Mater., Vol. 197 (2001), p.145.

[8] T. F. An, H. R. Guan, X. F. Sun and Z. Q. Hu: Oxid. Met. Vol. 54 (2000), p.301.

[9] Joint committee for powder diffraction standards card: Nos. 42-1468 (α) and 35-121 (θ), (1992).

[9] Fig. 6. Bright-field image of TGO formed on (a) as-coated and (b) grit-blasted bondcoat after 50 hours of oxidation at 1100°C.