Turbine airfoil degradation in the persian gulf war

Smialek, James L.; Archer, Frances A.; Garlick, R. G.

doi:10.1007/bf03222663

Cited by 114 publications

(92 citation statements)

References 2 publications

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“…This type of damage to 7YSZ TBCs, both APS and EB-PVD, is similar to what has been observed in aircraft gas-turbine engines but from deposits of molten calciummagnesium-alumino-silicate (CMAS) sand from the environment [15][16][17][18][19][20][21][22][23][24]. The molten CMAS glass penetrates the TBC microstructure and forms a relatively stiff glaze upon cooling [15][16][17][18][19]24].…”

Section: Introductionsupporting

confidence: 67%

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Degradation of Thermal Barrier Coatings from Deposits and Its Mitigation

Padture¹

2011

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Ceramic thermal barrier coatings (TBCs) used in gas-turbine engines afford higher operating temperatures, resulting in enhanced efficiencies and performance. However, in the case of syngas-fired engines, fly ash particulate impurities that may be present in syngas can melt on the hotter TBC surfaces and form glassy deposits. These deposits can penetrate the TBCs leading to their failure. In experiments using lignite fly ash to simulate these conditions we show that conventional TBCs of composition 93wt% ZrO 2 + 7wt% Y 2 O 3 (7YSZ) fabricated using the air plasma spray (APS) process are completely destroyed by the molten fly ash. The molten fly ash is found to penetrate the full thickness of the TBC. The mechanisms by which this occurs appear to be similar to those observed in degradation of 7YSZ TBCs by molten calcium-magnesium-aluminosilicate (CMAS) sand and by molten volcanic ash in aircraft engines. In contrast, APS TBCs of Gd 2 Zr 2 O 7 composition are highly resistant to attack by molten lignite fly ash under identical conditions, where the molten ash penetrates ~25% of TBC thickness. This damage mitigation appears to be due to the formation of an impervious, stable crystalline layer at the fly ash/Gd 2 Zr 2 O 7 TBC interface arresting the penetrating moltenfly-ash front. Additionally, these TBCs were tested using a rig with thermal gradient and simultaneous accumulation of ash. Modeling using an established mechanics model has been performed to illustrate the modes of delamination, as well as further opportunities to optimize coating microstructure. Transfer of the technology was developed in this program to all interested parties.

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Section: Introductionsupporting

confidence: 67%

“…The molten CMAS glass penetrates the TBC microstructure and forms a relatively stiff glaze upon cooling [15][16][17][18][19]24]. This results in the reduction of TBC strain-tolerance during engine heating-cooling cycles, causing the TBC to detach from the substrate much more quickly than if the CMAS was not present [20,21].…”

Section: Introductionmentioning

confidence: 99%

Degradation of Thermal Barrier Coatings from Deposits and Its Mitigation

Padture¹

2011

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“…Owing to its crystal chemistry, kimzeyite represents an almost ideal sink at the FTCMAS/ YSZ interface. In the general garnet structure X 3 [8] Y 2 [6] Z ), Fe is positioned solely as Fe 3+ on the Z-site. In addition to Zr and Mg, trace Y will most likely also enter the X-position.…”

Section: Recession Of An Eb-pvd Ysz Coated Turbine Bladementioning

confidence: 99%

“…1 Ingestion of airborne mineral dust during in-flight operation defines a serious issue for aero-engine performance and service life which has stimulated considerable research effort in industry and academia. [2][3][4][5][6] Upon heating in the combustor section molten or partially molten mineral particles impinge on hot surfaces. Besides possible reductions in air flow via clogging of turbine cooling air passages 7 the covering and infiltration of EB-PVD YSZ TBCs of turbine blades by molten inorganic particles is considered a major threat to the lifetime of turbine engines.…”

Section: Introductionmentioning

confidence: 99%

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits

Braue

Mechnich

2011

J. Am. Ceram. Soc.

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An in-service high-pressure turbine blade with a columnar, Y 2 O 3 -stabilized ZrO 2 (YSZ) thermal barrier coating (TBC) fabricated by electron-beam physical vapor deposition was investigated to access the TBC hot corrosion mechanisms during turbine operation. The TBC exhibits a throughthickness pore filling with anhydrite-type CaSO 4 . Chemical analysis of the CMAS-type particle deposits reveals relatively low SiO 2 but high CaO contents and substantial amounts of Fe 2 O 3 and TiO 2 . The hot corrosion scenario observed at the YSZ column tips involves newly formed CaZrO 3 and the garnet-type phase Ca 3 (Zr,Mg,Ti) 2 (Fe,Al,Si) 3 O 12 , also known as the mineral kimzeyite. The phase relationships were confirmed in laboratory experiments. CaSO 4 as well as the particle deposits prove to be effective solvents for YSZ introducing distinct solid-state reactions. The results support the idea of a dual YSZ hot corrosion process. A first stage controlled by a SiO 2 -free Ca-source, most likely primary CaSO 4 produces a thin CaZrO 3 layer. A second, CMAS-type stage providing high concentrations of Fe 2 O 3 , TiO 2 , and SiO 2 favors the formation of kimzeyite. The melting temperature of kimzeyite presumably defines a thermal operation limit for YSZ-based TBCs.

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“…For comparing with volcanic ash, the composition of CMAS 21) was included in Table 1. The main difference between volcanic ash and CMAS is the contents of Fe 2 O 3 and CaO.…”

Section: Methodsmentioning

confidence: 99%

Degradation of EB-PVD ZrO2–4 mol%Y2O3 thermal barrier coatings by volcanic ash deposits

Jang

Kim

et al. 2016

J. Ceram. Soc. Japan

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This work describes the degradation of ZrO 2 4 mol%Y 2 O 3 (YSZ) coatings obtained by EB-PVD. YSZ coatings were exposed at 1200°C for 10 min50 hr by isothermal heat treatment in the presence of an erosive impurity of volcanic ash. At the interface between the YSZ coatings and volcanic ash, the coatings were partially dissolved in the volcanic ash, resulting in the degradation of coatings by the formation of the reacted region. A ZrSiO 4 or glassy phase is formed by the chemical reaction between YSZ coatings and volcanic ash at 1200°C. The chemically reacted region from the top surface of the YSZ coatings showed a tendency for increased degradation depth with an increase in isothermal heat-treatment time.

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Turbine airfoil degradation in the persian gulf war

Cited by 114 publications

References 2 publications

Degradation of Thermal Barrier Coatings from Deposits and Its Mitigation

Degradation of Thermal Barrier Coatings from Deposits and Its Mitigation

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits

Degradation of EB-PVD ZrO<sub>2</sub>–4 mol%Y<sub>2</sub>O<sub>3</sub> thermal barrier coatings by volcanic ash deposits

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Turbine airfoil degradation in the persian gulf war

Cited by 114 publications

References 2 publications

Degradation of Thermal Barrier Coatings from Deposits and Its Mitigation

Degradation of Thermal Barrier Coatings from Deposits and Its Mitigation

Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO4 and Fe, Ti‐Rich CMAS‐Type Deposits

Degradation of EB-PVD ZrO<sub>2</sub>&ndash;4 mol%Y<sub>2</sub>O<sub>3</sub> thermal barrier coatings by volcanic ash deposits

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Recession of an EB‐PVDYSZ Coated Turbine Blade by CaSO₄ and Fe, Ti‐Rich CMAS‐Type Deposits

Degradation of EB-PVD ZrO<sub>2</sub>–4 mol%Y<sub>2</sub>O<sub>3</sub> thermal barrier coatings by volcanic ash deposits