Cyclic oxidation behavior of HVOF bond coatings deposited on La- and Y-doped superalloys

Pint, Bruce A.; Bestor, Michael A; Haynes, J. Allen

doi:10.1016/j.surfcoat.2011.06.044

Cited by 18 publications

(4 citation statements)

References 18 publications

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“…The ORNL evaluation will include polished bare, polished and CVD (chemical vapor deposition) aluminized [7], and/or grit-blasted and HVOF (high velocity oxygen fuel) coated superalloy coupons. The HVOF coated specimens use a commercial-type process and commercial NiCoCrAlYHfSi powder [8]. Coupons will be tested for 1000, 1hour cycles at 1050°C (1922ºF), 1100°C (2012ºF) and 1150°C (2102ºF) in dry and/or wet air with 10 min cooling between cycles.…”

Section: Mechanical Property Characterizationmentioning

confidence: 99%

New Single Crystal Superalloys, CMSX®-7 and CMSX®-8

Wahl¹,

Harris²

2012

Superalloys 2012 (Twelfth International Symposium)

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Section: Mechanical Property Characterizationmentioning

confidence: 99%

New Single Crystal Superalloys, CMSX®-7 and CMSX®-8

Wahl¹,

Harris²

2012

Superalloys 2012 (Twelfth International Symposium)

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“…Previous work with the MCrAlYHfSi bond coating without a YSZ top coat was not able to measure any difference in alumina growth rate or adhesion with the doped superalloys [59]. Characterization found no indication of La diffusing through the bond coating into the alumina scale.…”

Section: Cu Plate Aluminamentioning

confidence: 76%

The Effect of Water Vapor and Superalloy Composition on Thermal Barrier Coating Lifetime

et al. 2012

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New power generation concepts may contain higher water vapor in the turbine combustion gas due to the fuel or to steam dilution. To assess the effect of higher water vapor content on thermal barrier coating performance, furnace cycle (1h) testing was conducted in air with 10, 50 and 90 vol.% water vapor and compared to prior results in dry O 2 . The first series of experiments examined Pt diffusion (γ+γ') and Pt-modified aluminide (β) bond coatings on second-generation superalloy N5 at 1150°C with commercially vapor-deposited yttria-stabilized zirconia (YSZ) top coats. Compared to dry O 2 , the average coating lifetimes with Pt diffusion coatings were unaffected by the addition of water vapor while the Pt-modified aluminide coating average lifetime was reduced by >50% with 10% water vapor, but less reduction was observed with higher water contents. A similar set of coatings on low Re superalloy N515 showed no debit in lifetime with Pt aluminide bond coatings exposed to 10% water vapor. Characterization of the alumina scale thickness at failure showed a thicker oxide beneath the YSZ coating (compared to the scale without a top coating) for both types of bond coatings, and an increase in the oxide thickness with the addition of 10% water vapor. These observations were further studied using analytical transmission electron microscopy. The second series of experiments examined high velocity oxygen fuel (HVOF) MCrAlY and MCrAlYHfSi bond coatings and air-plasma sprayed YSZ top coatings on X4 superalloy substrates with and without Y and La additions. Compared to a dry O 2 baseline, the addition of 10% water vapor decreased the YSZ coating lifetime for either bond coating by ~30% at 1100°C. Substrates with Y and La additions showed no change in the average lifetime in 10% water vapor compared to standard X4. A further increase to 50% water vapor did not further decrease the average lifetime of one group of coatings. To better simulate base-load power generation, one group of specimens was cycled with 100h cycles, which substantially increased the coating lifetime. In each case, higher average lifetimes were observed with Hf in the bond coating. Initial characterization of the alumina scales formed at failure showed little effect of the water vapor addition, bond coating composition or substrate composition. For both series of coatings, the addition of 10% water vapor to the experiment reduced YSZ coating lifetime. However, increasing to 50% or 90% H 2 O showed no additional decrease in average YSZ lifetime.

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“…For the HVOF coating results, the Y and La doped X4 superalloys did not appear to improve TBC lifetime in this study, Figure 11. Previous work with the MCrAlYHfSi bond coating without a YSZ top coat was not able to measure any difference in alumina growth rate or adhesion with the doped superalloys [59]. Characterization found no indication of La diffusing through the bond coating into the alumina scale.…”

Section: Hvof/aps Coatings At 1100°cmentioning

confidence: 76%

The Effect of Water Vapor and Superalloy Composition on Thermal Barrier Coating Lifetime

Pint¹,

Haynes²,

Unocic³

et al. 2012

Superalloys 2012 (Twelfth International Symposium)

View full text Add to dashboard Cite

New power generation concepts may contain higher water vapor in the turbine combustion gas due to the fuel or to steam dilution. To assess the effect of higher water vapor content on thermal barrier coating performance, furnace cycle (1h) testing was conducted in air with 10, 50 and 90 vol.% water vapor and compared to prior results in dry O 2. The first series of experiments examined Pt diffusion (γ+γ') and Pt-modified aluminide (β) bond coatings on second-generation superalloy N5 at 1150°C with commercially vapor-deposited yttria-stabilized zirconia (YSZ) top coats. Compared to dry O 2 , the average coating lifetimes with Pt diffusion coatings were unaffected by the addition of water vapor while the Pt-modified aluminide coating average lifetime was reduced by >50% with 10% water vapor, but less reduction was observed with higher water contents. A similar set of coatings on low Re superalloy N515 showed no debit in lifetime with Pt aluminide bond coatings exposed to 10% water vapor. Characterization of the alumina scale thickness at failure showed a thicker oxide beneath the YSZ coating (compared to the scale without a top coating) for both types of bond coatings, and an increase in the oxide thickness with the addition of 10% water vapor. These observations were further studied using analytical transmission electron microscopy. The second series of experiments examined high velocity oxygen fuel (HVOF) MCrAlY and MCrAlYHfSi bond coatings and air-plasma sprayed YSZ top coatings on X4 superalloy substrates with and without Y and La additions. Compared to a dry O 2 baseline, the addition of 10% water vapor decreased the YSZ coating lifetime for either bond coating by ~30% at 1100°C. Substrates with Y and La additions showed no change in the average lifetime in 10% water vapor compared to standard X4. A further increase to 50% water vapor did not further decrease the average lifetime of one group of coatings. To better simulate base-load power generation, one group of specimens was cycled with 100h cycles, which substantially increased the coating lifetime. In each case, higher average lifetimes were observed with Hf in the bond coating. Initial characterization of the alumina scales formed at failure showed little effect of the water vapor addition, bond coating composition or substrate composition. For both series of coatings, the addition of 10% water vapor to the experiment reduced YSZ coating lifetime. However, increasing to 50% or 90% H 2 O showed no additional decrease in average YSZ lifetime.

show abstract

Cyclic oxidation behavior of HVOF bond coatings deposited on La- and Y-doped superalloys

Cited by 18 publications

References 18 publications

New Single Crystal Superalloys, CMSX®-7 and CMSX®-8

New Single Crystal Superalloys, CMSX®-7 and CMSX®-8

The Effect of Water Vapor and Superalloy Composition on Thermal Barrier Coating Lifetime

The Effect of Water Vapor and Superalloy Composition on Thermal Barrier Coating Lifetime

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Cyclic oxidation behavior of HVOF bond coatings deposited on La- and Y-doped superalloys

Cited by 18 publications

References 18 publications

New Single Crystal Superalloys, CMSX&reg;-7 and CMSX&reg;-8

New Single Crystal Superalloys, CMSX&reg;-7 and CMSX&reg;-8

The Effect of Water Vapor and Superalloy Composition on Thermal Barrier Coating Lifetime

The Effect of Water Vapor and Superalloy Composition on Thermal Barrier Coating Lifetime

Contact Info

Product

Resources

About

New Single Crystal Superalloys, CMSX®-7 and CMSX®-8

New Single Crystal Superalloys, CMSX®-7 and CMSX®-8