Microstructural and acoustic damage analysis and finite element stress simulation of air plasma-sprayed thermal barrier coatings under thermal cycling

Trunova, Olena; Bednarz, Piotr; Herzog, R.; Beck, T.; Singheiser, L.

doi:10.3139/146.101741

Cited by 11 publications

(4 citation statements)

References 13 publications

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“…The delamination failure occurred after 2432, 1827 and 670 cycles, respectively. The lifetimes as a function of T min and T max for the high temperature dwell times of 2 hours and 20 minutes, respectively, are summarized in Acoustic emission analysis applied in situ during thermal cycling in temperature range 60-1050°C, as reported in [8], proved that damage occurred during cooling at temperatures below the ductile-to-brittle transition temperature of the BC due to an increase in thermally induced stresses at the TBC/BC interface. With decreasing temperature range of the thermal cycle (increase of minimum temperature) thermal stresses contribute less to TBC degradation compared to the 02001-p. 3 thermally activated damage processes, especially TGO growth.…”

Section: Thermal Cyclingmentioning

confidence: 96%

TBCs for Gas Turbines under Thermomechanical Loadings: Failure Behaviour and Life Prediction

Beck

Trunova

Herzog³

et al. 2012

EPJ Web of Conferences

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Abstract. The present contribution gives an overview about recent research on a thermal barrier coating (TBC) system consisted of (i) an intermetallic MCrAlY-alloy Bondcoat (BC) applied by vacuum plasma spraying (VPS) and (ii) an Yttria Stabilised Zirconia (YSZ) top coat air plasma sprayed (APS) at Forschungszentrum Juelich, Institute of Energy and Climate Research (IEK-1). The influence of high temperature dwell time, maximum and minimum temperature on crack growth kinetics during thermal cycling of such plasma sprayed TBCs is investigated using infrared pulse thermography (IT), acoustic emission (AE) analysis and scanning electron microscopy. Thermocyclic life in terms of accumulated time at maximum temperature decreases with increasing high temperature dwell time and increases with increasing minimum temperature. AE analysis proves that crack growth mainly occurs during cooling at temperatures below the ductile-to-brittle transition temperature of the BC. Superimposed mechanical load cycles accelerate delamination crack growth and, in case of sufficiently high mechanical loadings, result in premature fatigue failure of the substrate. A life prediction model based on TGO growth kinetics and a fracture mechanics approach has been developed which accounts for the influence of maximum and minimum temperature as well as of high temperature dwell time with good accuracy in an extremely wide parameter range.

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Section: Thermal Cyclingmentioning

confidence: 96%

TBCs for Gas Turbines under Thermomechanical Loadings: Failure Behaviour and Life Prediction

Beck

Trunova

Herzog³

et al. 2012

EPJ Web of Conferences

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“…Yang et al performed the wavelet transform of AE signals to study the failure process of TBCs under tension [16] . Trunova et al reported the degradation evolution and failure mechanisms of APS TBCs during thermal cycling based on the analysis of microstructures and AE signals [17] . However, there are few works on the relationships between characteristic frequency spectrums of AE signals and fracture mechanisms of TBCs.…”

Section: Introductionmentioning

confidence: 99%

Acoustic emission analysis on tensile failure of air plasma-sprayed thermal barrier coatings

Yao

Dai

Mao

et al. 2012

Surface and Coatings Technology

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An acoustic emission technique was used to monitor the cracking behavior and fracture process of thermal barrier coatings subjected to tensile loading. Acoustic emission signals were extracted and preformed by fast Fourier transform, and their characteristic frequency spectrums and dominant bands were obtained to reveal fracture modes. Three different characteristic frequency bands were confirmed, corresponding to substrate deformation, surface vertical cracking and interface delamination, with the aid of scanning electronic microscopy observations. A map of the tensile failure mechanism of air plasma-sprayed thermal barrier coatings was HighlightsWe established several good correlations between AE data and fracture modes.The correlations can be utilized to reveal cracking profile and coating failure.A tensile failure mechanism of coating system was established.Fracture strength of thermal barrier coating has been obtained by this method.The method has a large advantage to study the failure of coating/film materials.

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“…It should, however, be noted that the number of specimens tested on the Caldecast XL 135 plate was limited, just one from each geometry. Even so, the cooling rate may not be the determining factor for TCF life; Trunova et al [15] found, for example, that the minimum temperature during cooling had a greater influence on life than the cooling rate. It should also be mentioned that the through-thickness temperature gradient in the specimens may be different between the rigs.…”

Section: Resultsmentioning

confidence: 99%

Thermal Cycling Fatigue of Thermal Barrier Coatings - Rig and Experiment Design

Eriksson

Brodin

Johansson

et al. 2014

AMR

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Ceramic thermal barrier coatings are used for thermal insulation in gas turbines to protect metallic components from high-temperature degradation. The ceramic coating may, due to its different coefficient of thermal expansion, crack and spall off the metallic component, thus rendering the component unprotected against high-temperature. Thermal cycling rigs of various designs are used to evaluate the durability of thermal barrier coatings. The present paper reports the result from a round robin test including three thermal cycling rigs at different locations. To better understand the influence of rig design on the thermal cyclic lives of thermal barrier coatings, some test parameters, such as the material of the specimen table and the cooling rate, were varied in one of the rigs. Furthermore, two different specimen geometries, rectangular and disc-shaped, were tested. The specimen table material was found to greatly influence the cooling rate of the specimens, more so than variations in the cooling airflow. The rectangular specimens were found to be more sensitive to test setup than the disc-shaped specimens; under certain conditions, the rectangular specimens could be made to fracture from the long side, rather than the short side of the specimen edge, which shortened the thermal cyclic life of the coatings.

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Microstructural and acoustic damage analysis and finite element stress simulation of air plasma-sprayed thermal barrier coatings under thermal cycling

Cited by 11 publications

References 13 publications

TBCs for Gas Turbines under Thermomechanical Loadings: Failure Behaviour and Life Prediction

TBCs for Gas Turbines under Thermomechanical Loadings: Failure Behaviour and Life Prediction

Acoustic emission analysis on tensile failure of air plasma-sprayed thermal barrier coatings

Thermal Cycling Fatigue of Thermal Barrier Coatings - Rig and Experiment Design

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