Accelerated Durability Testing of Coatings for Gas Turbines

Stiger, M. J.; Handoko, Riki; Beuth, Jack; Pettit, F. S.; Meier, G. H.

doi:10.1002/9781118787694.ch1

Cited by 3 publications

(3 citation statements)

References 7 publications

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“…Without considering the influence of indenter/TBC interaction higher apparent interfacial fracture toughness would be calculated for the heat treated TBC system. This result was in contrast to results presented by [1], [8], and [12] on EB-PVD systems with a 100 µm thick ceramic topcoat, but also in contrast to the results from interfacial indentation tests performed on EB-PVD systems with 220 µm thick ceramic coatings. Cross sections of the respective indented specimens showed that the penetration depth of the Rockwell diamond into the ceramic and also the inelastic deformation of the substrate was less in the heat treated system.…”

Section: Specimencontrasting

confidence: 99%

“…This may reduce the resistance against initiation and propagation of delamination cracks or, with other words, the interfacial fracture toughness. It is proposed to use the (apparent) interfacial fracture toughness for describing the damage accumulation before spallation [1] and, if the fracture toughness can be determined as a function of loading history, as a universal damage parameter in lifetime modelling [2].…”

Section: Introductionmentioning

confidence: 99%

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Interfacial Fracture Toughness Measurement of Thick Ceramic Coatings by Indentation

Bartsch

Mircea

Suffner

et al. 2005

KEM

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The basic requirement for the use of a ceramic coating is sufficient adhesion to its substrate. A measure of the adhesive properties of a coating is the interfacial fracture toughness. The test method applicable for interfacial fracture toughness measurements depends on the mechanical properties of the material system and the geometry of the test piece. In this work, indentation methods have been evaluated for the estimation of the fracture toughness of ceramic thermal barrier coatings on metallic substrates. Coatings of 100 to 300 µm thickness were applied by electron beam – physical vapour deposition. The performed test types were Vickers indentation at the interface of polished cross sections of the coating system and Rockwell indentation with a brale C indenter, penetrating the coating perpendicular to the surface. Both tests generate delamination, in which the delamination crack length corresponds to the interfacial fracture toughness. Fracture surfaces and cross sections of the fractured coatings were investigated by optical and scanning electron microscope. Determined fracture toughness values are discussed with respect to the loading conditions in the test and the fracture process – i.e. interaction between indenter and coating system and the crack propagation path.

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Section: Specimencontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Interfacial Fracture Toughness Measurement of Thick Ceramic Coatings by Indentation

Bartsch

Mircea

Suffner

et al. 2005

KEM

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“…It was also supposed that one of reasons resulted in TBCs failure is due to the macro-cracks originated in the mixed oxide zone. [6,7] From our data, high-temperature oxidation actually started from the EB-PVD process for depositing the top YSZ ceramic coating. During the EB-PVD process, the oxygen partial pressure of working chamber was about ~2×10 -6 kPa.…”

Section: Resultsmentioning

confidence: 84%

Effects of EB-PVD Process TGO Formation and Growth within Thermal Barrier Coatings

2007

MSF

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It has been found that under oxygen partial pressure of ~2×10-6 kPa, the high-temperature oxidation of thermal barrier coatings (TBCs) occurred during an electron beam physical vapor deposition (EB-PVD) process for producing the TBCs top ceramic coating. In the present investigation, two modified bond coats (BCs) of NiCrAlY with Si addition, and NiCrAlY with Co and Hf additions, were developed by Arc Ion-plating technique to study the effects of the EB-PVD process on thermally grown oxide (TGO) formation and growth. The isothermal and cyclic oxidation tests were conducted and the cross-sectional morphologies of the specimens were examined to compare the high-temperature oxidation behaviors of the two TBCs. It was found that a mixed oxide layer have been developed in the as-deposited TBCs with a NiCrAlYSi BC. The mixed oxide layer mainly included Cr2O3, NiO, Al2O3 and their spinel. With the mixed oxide layer, TBCs with the NiCrAlYSi BC showed a superior high-temperature resistance on later high-temperature exposure to TBCs with NiCoCrAlYHf BC, where no mixed oxide layer was observed. The pre-formed mixed oxide layer apparently shortened the time to fully develop a protective α-Al2O3 layer and therefore restrained the TGO growth in TBCs.

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Investigation on Failure in Thermal Barrier Coatings on Gas Turbine First-Stage Rotor Blade

Ali

Shehbaz

Bemporad

2018

J Fail. Anal. and Preven.

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Accelerated Durability Testing of Coatings for Gas Turbines

Cited by 3 publications

References 7 publications

Interfacial Fracture Toughness Measurement of Thick Ceramic Coatings by Indentation

Interfacial Fracture Toughness Measurement of Thick Ceramic Coatings by Indentation

Effects of EB-PVD Process TGO Formation and Growth within Thermal Barrier Coatings

Investigation on Failure in Thermal Barrier Coatings on Gas Turbine First-Stage Rotor Blade

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