The retention of thermal barrier coating systems on single-crystal superalloys: Effects of substrate composition

Wu, Rudder T.; Kawagishi, Kyoko; Harada, Hiroshi; Reed, Ruth

doi:10.1016/j.actamat.2008.03.046

Cited by 78 publications

(39 citation statements)

References 23 publications

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“…Since the failure of the TBCs occurred to such a large extent in the TC, previously suggested mechanisms for substrate influence on life -previous work has mainly focused on the BC/TGO interface [15][16][17][18][19] -may not sufficiently explain the difference in life for the specimens studied here.…”

Section: Oxidation and Interdiffusioncontrasting

confidence: 38%

“…It has been shown, mainly for EB-PVD TBCs, that the life of TBC systems depends on the substrate on which the TBC is deposited [15][16][17][18][19][20]. For EB-PVD TBCs, a few possible mechanisms for the observed difference in life have been suggested.…”

Section: Introductionmentioning

confidence: 99%

“…For EB-PVD TBCs, a few possible mechanisms for the observed difference in life have been suggested. For failure occurring mainly in the BC/TGO interface, it has been suggested that the substrate may influence the BC/TGO interface toughness [15,16]. Characteristics of the substrate that have been found to decrease TBC life include [17,18]: substrates high in refractory elements; substrates low in C, B and Cr; substrates with a larger CTE mismatch with the BC.…”

Section: Introductionmentioning

confidence: 99%

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Influence of substrate material on the life of atmospheric plasma sprayed thermal barrier coatings

Eriksson

Johansson

Brodin

et al. 2013

Surface and Coatings Technology

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Thermal barrier coatings (TBCs) are used in gas turbines to prolong the life of the underlying substrates and to increase the efficiency of the turbines by enabling higher combustion temperatures. TBCs may fail during service due to thermal fatigue or through the formation of non-protective thermally grown oxides (TGOs). This study compares two atmospheric plasma sprayed (APS) TBC systems comprising of two identical TBCs deposited on two different substrates (Haynes 230 and Hastelloy X). The thermal fatigue life was found to differ between the two TBC systems. The interdiffusion of substrate elements into the coating was more pronounced in the TBC system with shorter life, however, very few of the substrate elements (only Mn and to some extent Fe) formed oxides in the bond coat/top coat interface. Fractography revealed no differences in the fracture behaviour of the TBCs; the fracture occurred, in both cases, to about 60 % in the top coat close to the interface and the remainder in the interface. Nanoindentation revealed only small differences in mechanical properties between the TBC systems and a finite element crack growth analysis showed that such small differences did not cause any significant change in the crack driving force. The oxidation kinetics was found to be similar for both TBC systems for the formation * Corresponding author.

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Section: Oxidation and Interdiffusioncontrasting

confidence: 38%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of substrate material on the life of atmospheric plasma sprayed thermal barrier coatings

Eriksson

Johansson

Brodin

et al. 2013

Surface and Coatings Technology

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“…1). The characteristic trend was extended to higher temperatures for a 2 wt.% Co 3rd generation single crystal superalloy (blue/green split circles) [30,31] (Wu), the latter spanning the largest temperature range in a single study. Failure times reported for other 8% and 12% Co versions (not shown) were roughly 2/3 and 1/3 the lives of the 2% Co alloy, respectively.…”

Section: Eb-pvd Tbc Fct Life On Alumina-forming Systemsmentioning

confidence: 99%

“…Lower temperature testing (1038°C) resulted in lives N3400 h [43]. Some 33% life advantage was observed at 1135°C for a high activity aluminide compared to a low activity coating on PWA 1484 [31] (Wu et al). Similar failure times (not shown) were reported for CMSX-4, TMS 138A, and TMS 82, substrates, which were all measurably higher than those for SRR99 substrates.…”

Section: Temperature Effects Of Compiled Fct Livesmentioning

confidence: 99%

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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The Effect of Water Vapor and Superalloy Composition on Thermal Barrier Coating Lifetime

et al. 2012

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New power generation concepts may contain higher water vapor in the turbine combustion gas due to the fuel or to steam dilution. To assess the effect of higher water vapor content on thermal barrier coating performance, furnace cycle (1h) testing was conducted in air with 10, 50 and 90 vol.% water vapor and compared to prior results in dry O 2 . The first series of experiments examined Pt diffusion (γ+γ') and Pt-modified aluminide (β) bond coatings on second-generation superalloy N5 at 1150°C with commercially vapor-deposited yttria-stabilized zirconia (YSZ) top coats. Compared to dry O 2 , the average coating lifetimes with Pt diffusion coatings were unaffected by the addition of water vapor while the Pt-modified aluminide coating average lifetime was reduced by >50% with 10% water vapor, but less reduction was observed with higher water contents. A similar set of coatings on low Re superalloy N515 showed no debit in lifetime with Pt aluminide bond coatings exposed to 10% water vapor. Characterization of the alumina scale thickness at failure showed a thicker oxide beneath the YSZ coating (compared to the scale without a top coating) for both types of bond coatings, and an increase in the oxide thickness with the addition of 10% water vapor. These observations were further studied using analytical transmission electron microscopy. The second series of experiments examined high velocity oxygen fuel (HVOF) MCrAlY and MCrAlYHfSi bond coatings and air-plasma sprayed YSZ top coatings on X4 superalloy substrates with and without Y and La additions. Compared to a dry O 2 baseline, the addition of 10% water vapor decreased the YSZ coating lifetime for either bond coating by ~30% at 1100°C. Substrates with Y and La additions showed no change in the average lifetime in 10% water vapor compared to standard X4. A further increase to 50% water vapor did not further decrease the average lifetime of one group of coatings. To better simulate base-load power generation, one group of specimens was cycled with 100h cycles, which substantially increased the coating lifetime. In each case, higher average lifetimes were observed with Hf in the bond coating. Initial characterization of the alumina scales formed at failure showed little effect of the water vapor addition, bond coating composition or substrate composition. For both series of coatings, the addition of 10% water vapor to the experiment reduced YSZ coating lifetime. However, increasing to 50% or 90% H 2 O showed no additional decrease in average YSZ lifetime.

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The retention of thermal barrier coating systems on single-crystal superalloys: Effects of substrate composition

Cited by 78 publications

References 23 publications

Influence of substrate material on the life of atmospheric plasma sprayed thermal barrier coatings

Influence of substrate material on the life of atmospheric plasma sprayed thermal barrier coatings

Compiled furnace cyclic lives of EB-PVD thermal barrier coatings

The Effect of Water Vapor and Superalloy Composition on Thermal Barrier Coating Lifetime

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