Effect of increased water vapor levels on TBC lifetime with Pt-containing bond coatings

Pint, Bruce A.; Garner, George Walter; Lowe, Tracie; Haynes, J. Allen; Zhang, Y.

doi:10.1016/j.surfcoat.2011.06.008

Cited by 30 publications

(14 citation statements)

References 27 publications

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“…For 100 h cycles, specimens were placed in an alumina boat, heated to temperature over~4 h in flowing argon and furnace cooled after the cycle. Environments included (1) dry air, (2) air with 10 ± 1% or 50 ± 2% vol.% H 2 O and (3) buffered 90% (CO 2 -0.15% O 2 ) + 10% H 2 O [16,27]. The injected water was measured to calibrate its concentration.…”

Section: Methodsmentioning

confidence: 99%

“…The effects of water vapor on high temperature oxidation have been widely studied in the past 15 years [8][9][10][11][12][13][14][15][16], including alumina-forming alloys and TBC bond coatings but a complete understanding has yet to be achieved. Advanced characterization techniques, such as photo-stimulated luminescence piezospectroscopy (PLPS) to measure stress in alumina scales [17][18][19][20], also are being employed.…”

Section: Introductionmentioning

confidence: 99%

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The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

Lance

Unocic

Haynes

et al. 2014

Surface and Coatings Technology

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a b s t r a c t a r t i c l e i n f o Available online xxxx Keywords: Photo-stimulated luminescence piezospectroscopy (PLPS) Water vapor Bond coating Alumina scale TBCFurnace cycle testing of superalloy 1483 and X4 substrates with high velocity oxygen fuel (HVOF) NiCoCrAlYHfSi bond coatings and air plasma sprayed (APS) yttria-stabilized zirconia (YSZ) top coatings was conducted at 1100°C in various environments. Average thermal barrier coating (TBC) lifetimes were 5-6 times longer when 100 h cycles were used to simulate base-load power generation operation, compared to the 1 h aero-engine standard cycle. Longer exposure times for 100 h cycles increased the interdiffusion resulting in no clear effects of H 2 O and CO 2 additions on average TBC lifetime for the 1483 substrates, contrary to the results with 1 h cycles where the addition of H 2 O reduced TBC lifetime. The lower Al content and perhaps the higher Ti content in 1483 compared to X4 resulted in lower TBC lifetimes for 1483. Photo-stimulated luminescence piezospectroscopy (PLPS) and 3D microscopy were used to measure residual stress in the alumina scale and surface roughness, respectively, on specimens with and without a YSZ top coating.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

Lance

Unocic

Haynes

et al. 2014

Surface and Coatings Technology

Self Cite

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“…The resulting surface roughness parameters were determined by profilometry (CT350T with CHR1000 chromatic sensor, cyberTECHNOLOGIES GmbH, Ingolstadt, Germany). The mean arithmetic average roughness, S a , and the root mean square slope, S dq , are displayed in Table III. Furnace cycling experiments were conducted in automated cyclic rigs [17] where four Cobased and four Ni-based free-standing BC samples were cycled together. One cycle comprised one hour at high temperature in the furnace and ten minutes cooling in air after retraction of the samples from the furnace.…”

Section: Methodsmentioning

confidence: 99%

Effects of thermal cycling parameters on residual stresses in alumina scales of CoNiCrAlY and NiCoCrAlY bond coats

Nordhorn

Mücke

Unocic

et al. 2014

Surface and Coatings Technology

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Furnace cycling experiments were performed on free-standing high-velocity oxygen-fuel bond coat samples to investigate the effect of material composition, surface texture, and cycling conditions on the average stresses in the formed oxide scales after cooling. The oxide scale thicknesses were determined by SEM image analyses and information about the stresses were acquired by photo-stimulated luminescence-spectroscopy. Additionally, the scale thickness dependent stress fields were calculated in finite-element analyses including approximation functions for the surface roughness derived on the basis of profilometry data. The evolution of the average residual stress as a function of oxide scale thickness was subject to stochastic fluctuations predominantly caused by local scale spallations. In comparison to the supplementing modeling results, thermal stresses due to mismatch of thermal expansion coefficients are identified as the main contribution to the residual stresses. The theoretical results emphasize that analyses of spectroscopic data acquired for average stress investigations of alumina scales rely on detailed information about microstructural features.

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“…Pint et al [36] reported that the addition of water vapour significantly influenced the surface roughness of Pt-modified aluminide coating specimens. Therefore, in order to investigate the surface roughness (R a ) of the oxide scales formed on b-NiAlHf coatings, AFM measurements were carried out in 10 lm 9 10 lm area.…”

Section: Surface Roughness Of the Oxide Scalesmentioning

confidence: 99%

Oxidation behaviour of electron beam physical vapour deposition β-NiAlHf coatings at 1100 °C in dry and humid atmospheres

et al. 2015

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NiAl intermetallic compounds attract increasing attention for high-temperature applications due to their combination of excellent properties, especially as metallic protective coatings on superalloys or as bond coats in thermal barrier coatings (TBCs). Oxidation behaviour of the b-NiAlHf coatings prepared by electron beam physical vapour deposition (EB-PVD) was investigated at 1100°C for short time and 100 h in 20 % O 2 ? Ar and 15 % H 2 O ? Ar, respectively. The results of mass changes reveal that the addition of minor reactive element Hf significantly improves the cyclic oxidation resistance of the bNiAl coatings in both dry and humid atmospheres. During the initial oxidation stage, water vapour retards the phase transformation from h-Al 2 O 3 to a-Al 2 O 3 . Moreover, compared with the case in dry atmosphere, water vapour significantly reduces the surface roughness of the oxide scales formed on EB-PVD b-NiAlHf coatings after 100 h cyclic oxidation, which corresponds with the difference of surface morphologies of the oxide scales.

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Effect of increased water vapor levels on TBC lifetime with Pt-containing bond coatings

Cited by 30 publications

References 27 publications

The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

Effects of thermal cycling parameters on residual stresses in alumina scales of CoNiCrAlY and NiCoCrAlY bond coats

Oxidation behaviour of electron beam physical vapour deposition β-NiAlHf coatings at 1100 °C in dry and humid atmospheres

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