Ceramic thermal barrier coatings

Liebert, C. H.; Miller, Robert A.

doi:10.1021/i300015a004

Cited by 34 publications

(7 citation statements)

References 10 publications

(20 reference statements)

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“…Delamination of the bond coat, oxidation of the substrate and spallation of the TBC at very high stresses during creep were evident ( Figures 7 and 9). The TBC or top coat layer is delaminated from the 488 CANADIAN METALLURGICAL QUARTERLY, VOL 47, NO 4 bond coat and subsequently the bond coat is delaminated from the substrate. Figure 10 reveals the variation of rupture strength, S of the substrate material in the temperature range of 550 to 800°C, for various rupture times.…”

Section: Resultsmentioning

confidence: 99%

“…The ceramic TBCs provide an increase in the thermal inertia of the turbine components and therefore a reduction of the severe thermal temperature gradients during heating and cooling [1,8]. It was established that, under conditions simulating jet engine applications [4,5], one significant contributor to TBC failure is spalling from the oxidation of the bond coat; many studies have concentrated on the time to spalling as a function of heat flux [6][7][8][9] and as functions of surface stresses and crack tip opening [9]. Analysis of life data indicates that cyclic thermal loading and thermal exposure play synergistic roles in controlling the spallation life of the coating [17].…”

Section: Introductionmentioning

confidence: 99%

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Damage Resistance of a Thermal Barrier Coated Superalloy for Combustor Liners in Aero Turbines During Fatigue and Creep

Ray¹,

Goswami²,

Kar³

et al. 2008

Canadian Metallurgical Quarterly

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This paper deals with an evaluation of the lifetime of a thermal barrier coated (TBC) C263 superalloy under fatigue and creep loading. Results revealed that both TBC and bond-coated substrate had higher endurance limits than the base alloy, while the opposite was found for high stress, low cyclic lifetimes. At high stress, the premature failure for these two materials is possibly due to high stress crack initiation/growth in the TBC/bond coat layers. Oxidation is the cause of the reduced life of the bare substrate as compared to the coated substrate while fatigue and creep experiments are carried out in an oxidizing environment. During 800°C fatigue, the bare specimens behave differently from the coated specimens, but both the bond-coated only and bond coat + TBC specimens seem to exhibit very similar results that are within experimental scatter. Delamination of the bond coat, oxidation of the substrate and spallation of the ceramic layer were evident at very high fatigue and creep stresses. Lateral cracks that grew in the ceramic layer parallel to the stress axis were responsible for spallation of the top coat (TBC) at a very high fatigue stress, whereas, at low creep stress, spallation of the top coat was due to the growth of alumina scale (of thickness >3µm) at the top coat (TBC)/bond coat interface.Résumé -Cet article a trait à une évaluation de la durée de vie d'un superalliage C263 revêtu d'une barrière thermique (TBC) sous charge de fatigue et de fluage. Les résultats ont révélé que le TBC et le substrat revêtu d'une couche d'ancrage avaient tous deux une résistance à la fatigue plus élevée que l'alliage de base, alors que l'opposé était vrai pour des durées de vies à contraintes élevées et oligocycliques. Aux contraintes élevées, la défaillance prématurée de ces deux matériaux est possiblement due à l'initiation et à la croissance de fissure de haute contrainte dans les couches de TBC/d'ancrage. L'oxydation est la cause de la durée de vie réduite du substrat nu comparé au substrat revêtu lorsque que les expériences de fatigue et de fluage sont effectuées dans un environnement oxydant. Lors de la fatigue à 800°C, les échantillons nus se comportaient différemment des échantillons revêtus, mais les échantillons avec seulement une couche d'ancrage et les échantillons avec couche d'ancrage + TBC semblaient tous deux exhiber des résultats très similaires qui sont dans la limite de dispersion expérimentale. Le délaminage de la couche d'ancrage, l'oxydation du substrat et la spallation de la couche de céramique étaient évidents à des contraintes très élevées de fatigue et de fluage. Des fissures latérales qui croissaient dans la couche de céramique en parallèle à l'axe de contrainte étaient responsables de la spallation de la couche supérieure (TBC) à une contrainte très élevée de fatigue alors que, à une faible contrainte de fluage, la spallation de la couche supérieure était due à la croissance des écailles d'alumine (d'épaisseur > 3 µm) à l'interface couche supérieure (TBC)/couche d'ancrage.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Damage Resistance of a Thermal Barrier Coated Superalloy for Combustor Liners in Aero Turbines During Fatigue and Creep

Ray¹,

Goswami²,

Kar³

et al. 2008

Canadian Metallurgical Quarterly

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“…The excellent thermal stability, tensile and fatigue strengths, resistance to creep and hot corrosion, and micro-structural stability possessed by nickel-based superalloy render the material an optimum choice for application in turbine blades (Sims, 1999;Boyce, 2002;Huda, 2007). These Nickel based superalloy are the standard material for hot stages of gas turbines, where blades are subjected to high mechanical stresses, elevated temperatures and in aggressive environments (Ray, 2000;Ray and Steinbrech, 1999;Brindley and Miller;1990;Liebert and Miller, 1984;Kokini et al, 1997;Lelait et al, 1989;Kokini and Takeuchi, 1994;Godiwalla et al, 2001;Roy et al, 2001Roy et al, , 2006Chiu and case, 1991;Owen and Hinton, 1980;Brandle et al, 1996;Roy et al, 2004;Gupta et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

Failure analysis of gas turbine blades in a gas turbine engine used for marine applications

Rao¹,

Kumar²,

Prasad³

2014

Int. J. Eng. Sci. Tech

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High pressure temperature (HPT) turbine blade is the most important component of the gas turbine and failures in this turbine blade can have dramatic effect on the safety and performance of the gas turbine engine. This paper presents the failure analysis made on HPT turbine blades of 100 MW gas turbine used in marine applications. The gas turbine blade was made of Nickel based super alloys and was manufactured by investment casting method. The gas turbine blade under examination was operated at elevated temperatures in corrosive environmental attack such as oxidation, hot corrosion and sulphidation etc. The investigation on gas turbine blade included the activities like visual inspection, determination of material composition, microscopic examination and metallurgical analysis. Metallurgical examination reveals that there was no micro-structural damage due to blade operation at elevated temperatures. It indicates that the gas turbine was operated within the designed temperature conditions. It was observed that the blade might have suffered both corrosion (including HTHC & LTHC) and erosion. LTHC was prominent at the root of the blade while the regions near the tip of the blade were affected by the HTHC. It could be concluded that the turbine blade failure might be caused by multiple failure mechanisms such as hot corrosion, erosion and fatigue. Hot corrosion could have reduced the thickness of the blade material and thus weakened the blade. This reduction of the blade thickness decreases the fatigue strength which ultimately led to the failure of the turbine blade.

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“…and so there is a possibility of increasing the turbine inlet temperature and/ or cooling air mass flow. It was established that under conditions simulating jet engine applications [7,8], one significant contributor to such spalling is oxidation of the bond coat. Many studies have concentrated on the time to spalling as a function of heat flux [9][10][11][12][21][22][23] and as a function of surface stresses and crack tip opening [12].…”

Section: Introductionmentioning

confidence: 99%

Fatigue and creep damage resistance of a thermal barrier coated superalloy for combustor liners in aero turbines

Ray

Goswami²,

Tiwary

et al. 2010

Trans Indian Inst Met

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Fatigue testing of thermal barrier coated (TBC), bond coated only and bare Superni C263 superalloy was conducted at 800ºC in air. Fatigue results reveal that the endurance limits for the TBC and bond coated substrate was substantially higher than that of the base alloy, while the opposite was found for high stress, low cyclic life times. It appears that the increase in endurance limit for the TBC and bond coated superalloy is due to load shifting to the bond coat, and the premature failure for these two materials is possibly due to high stress crack imitation/growth in the TBC/bond coat layers. In addition to fatigue, accelerated creep properties of thermal barrier coated (TBC) Superni C263 were evaluated. Creep results reveal that the life of the TBC composite under accelerated creep condition is substantially high compared to that of the bare substrate. The mode of fracture in the substrate at very high stresses was transgranular whereas that at low stresses was intergranular. Delamination of bond coat, oxidation of the substrate and spallation of the ceramic layer were evident at very high stress. It was evident that the substrate has negligible estimated rupture strength after 10,000 hours of service exposure.

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Ceramic thermal barrier coatings

Cited by 34 publications

References 10 publications

Damage Resistance of a Thermal Barrier Coated Superalloy for Combustor Liners in Aero Turbines During Fatigue and Creep

Damage Resistance of a Thermal Barrier Coated Superalloy for Combustor Liners in Aero Turbines During Fatigue and Creep

Failure analysis of gas turbine blades in a gas turbine engine used for marine applications

Fatigue and creep damage resistance of a thermal barrier coated superalloy for combustor liners in aero turbines

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