Oxide Dispersion Strengthened Bond Coats with Higher Alumina Content: Oxidation Resistance and Influence on Thermal Barrier Coating Lifetime

Vorkötter, Christoph; Hagen, S. P.; Pintsuk, G.; Mack, Daniel Emil; Virtanen, Sannakaisa; Guillon, Olivier; Vaßen, Robert

doi:10.1007/s11085-019-09931-z

Cited by 11 publications

(22 citation statements)

References 36 publications

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“…AE11965 had the slowest TGO growth rate, however, lifetime of the TBC with AE11965 bond coat is not the longest, in fact, much lower than the TBC with AE11966 bond coat, thus TGO thickness is critical, but other factors also play important role in the TBC thermal cycle lifetime. Mixed oxides (spinel type) were considered to be detrimental to TBC thermal cycle lifetime and Ni, Cr, Co and Al usually formed spinel type oxides above the alumina layer of bond coats [10,[42][43][44][45][46][47]. In the present study, mixed oxides were also observed in the TBCs with D4700 and A386 bond coat, but were never found in the TBCs with new alloy bond coats.…”

Section: Tgo Configurationsupporting

confidence: 46%

“…In the present study, mixed oxides were also observed in the TBCs with D4700 and A386 bond coat, but were never found in the TBCs with new alloy bond coats. High oxygen partial pressure promotes formation of mixed oxides (spinel type) [10,[46][47], and quick formation of dense α-Al2O3 thin layer at the beginning of exposure to air at high temperature prevented from the generation of mixed oxides [47]. The influence of oxygen partial pressure on the formation of mixed oxide was excluded in the present study because new alloys bond coats and benchmarking alloys bond coats experienced the same environments during the sample preparation and testing.…”

Section: Tgo Configurationmentioning

confidence: 99%

“…Taylor and Walsh [8] measured CTE of the bond coats sprayed by almost all commercially available bond coat alloys of NiCrAlY, NiCoCrAlY, CoNiCrAlY and CoCrAlY, and results indicated that the CTE values for different commercially available MCrAlY alloys are very close. It has been explored that adding dispersed alumina particles into MCrAlY to reduce CTE of bond coat and promote the formation of dense thin layer of α-Al2O3 at the beginning of thermal exposure in order to improve TBC thermal cycle lifetime, however, the performance of TBC was only increased moderately [9][10]. So far, an effective method to dramatically reduce CTE mismatch between top coat and bond coat and to achieve high thermal cycle lifetime significantly has not been reported.…”

Section: Introductionmentioning

confidence: 99%

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Principle and Practice to Achieve Improvements in TBC Thermal Cycle Lifetime

Sharobem

Zhou

et al. 2021

Thermal Spray 2021: Proceedings From the International Thermal Spray Conference

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As a critical technology; thermal barrier coatings (TBC) have been used in both aero engines and industrial gas turbines for a few decades; however; the most commonly used MCrAlY bond coats which control air plasma sprayed (APS) TBC lifetime are still deposited by the powders developed in 1980s. This motivates a reconsideration of development of MCrAlY at a fundamental level to understand why the huge efforts in the past three decades has so little impact on industrial application of MCrAlY alloys. Detailed examination of crack trajectories of thermally cycled samples and statistic image analyses of fracture surface of APS TBCs confirmed that APS TBCs predominately fails in top coat. Cracks initiate and propagate along splat boundaries next to interface area. TBC lifetime can be increased by either increasing top coat fracture strength (strain tolerance) or reducing the tensile stress in top coat or both. By focusing on the reduction of tensile stress in top coats; three new bond coat alloys have been designed and developed; and the significant progress in TBC lifetime have been achieved by using new alloys. Extremely high thermal cycle lifetime is attributed to the unique properties of new alloys; such as remarkably lower coefficient of thermal expansion (CTE) and weight fraction of β phase; absence of mixed / spinel oxides; and TGO self repair ability; which cannot be achieved by the existed MCrAlY alloys.

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Section: Tgo Configurationsupporting

confidence: 46%

Section: Tgo Configurationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Principle and Practice to Achieve Improvements in TBC Thermal Cycle Lifetime

Sharobem

Zhou

et al. 2021

Thermal Spray 2021: Proceedings From the International Thermal Spray Conference

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“…A number of studies have been reported to conduct the TBC isothermal oxidation at 1100 • C. For example, Jonnalagadda et al conducted the test with a maximum exposure of 3000 h using commercial furnace [88]; Goral et al and Izadinia et al conducted the test for 1000 h also using the commercial furnace [72,89]; Paraschiv et al conducted the test for maximum 600 h [90]; and Vorkotter et al used commercial thermogravimetric analyzer (TGA) for a maximum test exposure of 70 h [91]. The temperature of 1100 • C is the lowest maximum material temperature of gas turbine components that are made of superalloys and coated with TBC [4].…”

Section: Isothermal Oxidation Test Rigmentioning

confidence: 99%

“…The above-mentioned articles [80][81][82] do not consider the addition of cooling systems in their work. Studies that have been conducted using typical commercial furnace [32,72,77,[83][84][85][86][87][88][89][90][91][92][93][94][95][96][97][98][99] have also proven to not be capable of simulating the cooling air effect on TBC in advanced gas turbine operating condition. The developed custom-made test rigs are also limited to short test duration under cyclic condition and no cooling air effect under prolonged steady-state operating conditions.…”

Section: Isothermal Oxidation Test Rigmentioning

confidence: 99%

Test-Rig Simulation on Hybrid Thermal Barrier Coating Assisted with Cooling Air System for Advanced Gas Turbine under Prolonged Exposures—A Review

et al. 2021

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Thermal barrier coating (TBC) and cooling air systems are among the technologies that have been introduced and applied in pursuing the extensive development of advanced gas turbine. TBC is used to protect the gas turbine components from the higher operating temperature of advanced gas turbine, whereas cooling air systems are applied to assist TBC in lowering the temperature exposure of protected surfaces. Generally, a gas turbine operates in three main operational modes, which are base load, peak load, and part peak load. TBC performance under these three operational modes has become essential to be studied, as it will provide the gas turbine owners not only with the behaviors and damage mechanism of TBC but also a TBC life prediction in a particular operating condition. For TBC under base load or so called steady-state condition, a number of studies have been reviewed and discussed. However, it has been found that most of the studies have been conducted without the assistance of a cooling air system, which does not simulate the TBC in advanced gas turbine completely. From this review, the studies on TBC-assisted cooling air system to simulate the advanced gas turbine operating conditions have also been summarized, which are limited to test rig simulations under thermal cyclic mode where thermal cyclic represents peak and part peak load conditions. The equipment used to simulate the gas turbine operating condition, test temperatures, and durations are parameters that have been taken into consideration under this review. Finally, a test rig that is capable of simulating both TBC and cooling air effects at a high operating temperature of advanced gas turbines for prolonged exposure under steady-state condition has been proposed to be developed.

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Additive Manufacturing of Columnar Thermal Barrier Coatings by Laser Cladding of Ceramic Feedstock

Vorkötter

Mack

Vaßen

et al. 2022

Adv Materials Technologies

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This study presents a new laser‐cladding‐based additive manufacturing technique named Clad2Z. Using a robot‐mounted confocal powder nozzle with axial infrared laser beam, ceramic columns with a diameter of 450 µm and an adjustable height are developed. Influence of laser parameters and robot movements on shape and microstructure is analyzed. As an example application, the common material yttria‐stabilized zirconia (YSZ) is used to deposit columnar‐structured thermal barrier coatings (TBCs). The excellent thermal cycling performance of the Clad2Z samples is demonstrated by burner rig tests and comparing lifetime and failure mechanism with conventional TBC systems.

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Oxide Dispersion Strengthened Bond Coats with Higher Alumina Content: Oxidation Resistance and Influence on Thermal Barrier Coating Lifetime

Cited by 11 publications

References 36 publications

Principle and Practice to Achieve Improvements in TBC Thermal Cycle Lifetime

Principle and Practice to Achieve Improvements in TBC Thermal Cycle Lifetime

Test-Rig Simulation on Hybrid Thermal Barrier Coating Assisted with Cooling Air System for Advanced Gas Turbine under Prolonged Exposures—A Review

Additive Manufacturing of Columnar Thermal Barrier Coatings by Laser Cladding of Ceramic Feedstock

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