High Growth Rate YSZ Thermal Barrier Coatings Deposited by MOCVD Demonstrate High Thermal Cycling Lifetime

Journal Article · Sat Jan 01 00:00:00 EST 2011 · Materials Science and Engineering A

DOI:https://doi.org/10.1016/j.msea.2010.09.063· OSTI ID:1000427

Varanasi, Venu G ^[1]; Besmann, Theodore M ^[1]; Payzant, E Andrew ^[1]; Pint, Bruce A ^[1]; Lothian, Janet L ^[1]; Anderson, Timothy J ^[2]

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1. ORNL
2. University of Florida

Yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBC) were prepared by metalorganic chemical vapor deposition (MOCVD) using Y(OBut{sup n}){sub 3}, Zr(OBut{sup n}){sub 4} precursors and O{sub 2} carrier gas. A thermodynamic analysis guided experiments by optimizing elemental molar (n) stoichiometric ratios for the (Zr-Y-O-C-H system). This analysis showed single-phase YSZ was favored at 950 C, 1 kPa, n{sub O}/(n{sub Y} + n{sub Zr}) > 30, n{sub Y}/(n{sub Y} + n{sub Zr}) = 0.06-0.10 (fixed n{sub C}, n{sub H}). Experimental YSZ growth had multiple phases (fcc, monoclinic), had a relatively high growth rate (43 {micro}m/h, 1005 C), had an Arrhenius dependence (845-950 C, E{sub a} = 53.8 {+-} 7.9 kJ/mol), had columnar grains (SEM analysis), and had a coating through-thickness n{sub Y}/(n{sub Y} + n{sub Zr}) = 0.04 (EPMA analysis). Doubling the inlet yttrium precursor mole fraction resulted in fcc YSZ growth with a coating through-thickness n{sub Y}/(n{sub Y} + n{sub Zr}) = 0.07. Hot-insertion thermal cycling of YSZ coatings on FeCrAlY bond coats showed >1000 h lifetime, matching current standards for EB-PVD YSZ coatings.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Temperature Materials Lab. (HTML)
• Sponsoring Organization: FE USDOE - Office of Fossil Energy (FE); USDOE Office of Energy Efficiency and Renewable Energy (EERE)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1000427
• Journal Information: Materials Science and Engineering A, Vol. 528, Issue 3; ISSN 0921-5093
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL VAPOR DEPOSITION
COATINGS
LIFETIME
PRECURSOR
THERMAL BARRIERS
THERMAL CYCLING
THERMODYNAMICS
YTTRIUM