Oxidation-induced failure of EB-PVD thermal barrier coatings

Tolpygo, V.K.; Clarke, David R.; Murphy, K. S.

doi:10.1016/s0257-8972(01)01482-7

Cited by 148 publications

(78 citation statements)

References 11 publications

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“…Using the nominal material parameters, geometry, and temperature in Table 2, it is predicted that the compressive stress in the Al 2 O 3 scale would be~−3700 MPa for metallic substrates. This is in the range of values measured by photoluminescence spectroscopy [22]. In contrast, for Ti 2 AlC substrates, the stresses in the Al 2 O 3 scale would be just − 521 MPa (~1/7 that of the metallic system).…”

Section: Residual Stress and Strain Energy Factormentioning

confidence: 68%

“…This may be a combination of stress concentrations that occur at asperities, debonding at valleys in any ratcheting/rumpling distortion, and increases in strain energy as the scale grows. An empirical value of 7 μm has often been mentioned as a 'critical' scale thickness, x c , for TBC failure on superalloy substrates [22]. Fig.…”

Section: Scale Thickness At Failurementioning

confidence: 99%

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Oxidative durability of TBCs on Ti2AlC MAX phase substrates

Smialek

Harder

Garg

2016

Surface and Coatings Technology

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Air plasma spray (APS) and plasma-spray-physical vapor deposition (PS-PVD) yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBC),~80-100 μm thick, were produced on a commercial Ti 2 AlC MAX phase compound. They were oxidized in interrupted furnace tests for 500 h each, at five successive temperatures from 1100°-1300°C. The APS coating survived 2400 accumulated hours, failing catastrophically after 500 h at 1300°C. Porosity, large cracks, sintering, and high monoclinic YSZ phase contents were seen as primary degradation factors. The PS-PVD coating remained completely intact over 2500 total hours (65 cycles) including 500 h at 1300°C, exhibiting only fine porosity and microcracking, with less monoclinic. These Ti 2 AlC systems achieved a minimum α-Al 2 O 3 scale thickness of 29 and 35 μm, respectively, as compared to~6 ± 2 μm on average at failure for conventional bond coats on superalloys. Accordingly, times predicted from thermogravimetric analyses (TGA) of oxidation kinetics project an improvement factor of~25-50× for the time to achieve these scale thicknesses at a given temperature. Extreme oxidative TBC durability is achieved because the thermal expansion coefficient of Ti 2 AlC is only slightly different than those for α-Al 2 O 3 and YSZ. The strain energy term driving scale and TBC failure is therefore believed to be fundamentally diminished from the large compressive stress produced by higher expansion superalloys.Published by Elsevier B.V.

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Section: Residual Stress and Strain Energy Factormentioning

confidence: 68%

Section: Scale Thickness At Failurementioning

confidence: 99%

Oxidative durability of TBCs on Ti2AlC MAX phase substrates

Smialek

Harder

Garg

2016

Surface and Coatings Technology

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“…This thickness value arose from correlations with failure in a number of studies [11,13,12,47], although we emphasize that it is not a strict, universal criterion, sufficient to trigger failure. Nevertheless, it is seen in Figs.…”

Section: Eb-pvd Tbc Fct Life On Nicocraly Bond Coatsmentioning

confidence: 99%

“…These help extend the trend-line to lower temperatures, but with one study [40] showing lives about ½ the others. Two studies showed a life increase of 30-40% at 1150°C and 1121°C by not grit blasting [12,41]. The effect of pre-oxidation (1150°C, 5 h, air; modified 2nd generation single crystal superalloy) provided another insight into improved performance by reducing the amount of transition alumina scales [27] (Tolpygo and Clarke, 2005).…”

Section: Temperature Effects Of Compiled Fct Livesmentioning

confidence: 99%

“…Here the effects of interdiffusion and other thermomechanical instabilities between bond coats and substrates are precluded, while scale growth and thermal expansion issues between metals and oxides remain. In that regard, failure lives are compared to oxidative times predicted to obtain scales of a specified 'critical thickness,' typically around 5-10 μm [11][12][13], although other contributing factors must still be present. The original motivation of this compilation …”

Section: Introductionmentioning

confidence: 99%

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Compiled furnace cyclic lives of EB-PVD thermal barrier coatings

Smialek

2015

Surface and Coatings Technology

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a b s t r a c t a r t i c l e i n f oFurnace cycling has been widely used to study the failure of EB-PVD thermal barrier coatings. This contribution compiles TBC furnace cyclic lives over a broad literature base to highlight optimum systems and generalized trends not always apparent in one study. Systems included typical bond coats (Pt-modified aluminides, diffused Pt-only γ/γ′, and NiCoCrAlY (± Pt, Hf) overlays) and superalloy substrates (1st, 2nd, 3rd generation single crystals, directionally solidified, or conventionally cast). Pretreatments included controlled low p(O 2 ) bond coat pre-oxidation and grit blasting (or none). The aggregate lives (~70) suggest a general trend with temperature,~10-fold decrease for every 100°C increase. Measured alumina scale thicknesses (~30) were, on average, 6.1 ± 1.8 μm at failure and independent of temperature for conventional systems. Most failures thus occurred in less time than that predicted to grow 7 μm of alumina scale (as estimated from separate TGA studies of a Ptmodified aluminide coated 2nd generation single crystal superalloy). A tentative activation energy indicated from the broad distribution of failure times was~280 kJ/mol, while that from homogeneous TGA testing was 380 kJ/mol, with regression coefficients of r 2 = 0.57 and 0.98, respectively. Published by Elsevier B.V.

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Parameters affecting TGO growth rate and the lifetime of TBC systems with MCrAlY‐bondcoats

Toscano

Naumenko

Gil

et al. 2008

Materials & Corrosion

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In the present work different parameters which affect the oxide growth on MCrAlY-bondcoats have been studied, in an attempt to find a reliable way to define the critical oxide thickness to failure of an EB-PVD thermal barrier coating (TBC). It was found that the variation of selected parameters such as oxidation temperature, surface roughness, and bondcoat thickness certainly alters the thermally grown oxide (TGO) growth rate. However, simultaneously the morphology, composition, and/or microstructure of the oxide are changed, which can affect the critical TGO thickness to failure in a TBC system. In contrast, the variation of the oxygen partial pressure of the oxidizing atmosphere led to different TGO growth rates without significantly changing the oxide morphology and composition. Comparing the TGOs grown at different rates in the specimens exposed to high pO 2 and low pO 2 atmospheres, it was estimated that at failure the oxide scales in both specimens have reached a similar critical thickness.

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Oxidation-induced failure of EB-PVD thermal barrier coatings

Cited by 148 publications

References 11 publications

Oxidative durability of TBCs on Ti2AlC MAX phase substrates

Oxidative durability of TBCs on Ti2AlC MAX phase substrates

Compiled furnace cyclic lives of EB-PVD thermal barrier coatings

Parameters affecting TGO growth rate and the lifetime of TBC systems with MCrAlY‐bondcoats

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