The behavior of high-purity, low-density air plasma sprayed thermal barrier coatings

Helminiak, M.A.; Yanar, N. M.; Pettit, F. S.; Taylor, T.A.; Meier, G. H.

doi:10.1016/j.surfcoat.2009.09.065

Cited by 34 publications

(22 citation statements)

References 9 publications

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“…[20] A good correlation was shown between the cyclic life of the APS TBC and TBC/ substrate CTE mismatch (Figure 38). The magnitude of the CTE mismatch between the superalloy substrate and top coat will affect the elastic strain energy stored in the topcoat during cooling from the exposure temperature.…”

Section: A Tbc Failuresmentioning

confidence: 81%

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Comparison of the Failures during Cyclic Oxidation of Yttria-Stabilized (7 to 8 Weight Percent) Zirconia Thermal Barrier Coatings Fabricated via Electron Beam Physical Vapor Deposition and Air Plasma Spray

Yanar

Helminiak

Meier

et al. 2010

Metall Mater Trans A

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The failures during oxidation of electron beam physical vapor deposition (EBPVD) and air plasma spray (APS) yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBCs) on different bond coats, namely, platinum-modified aluminide and NiCoCrAlY, are described. It is shown that oxidation of the bond coats, along with defects existing near the TBC/bond coat interface, plays a very important role in TBC failures. Procedures to improve TBC performance via modifying the oxidation characteristics of the bond coats and removing the as-processed defects are discussed. The influence of exposure conditions on TBC lives is described and factors such as cycle frequency and thermal gradients are discussed.

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Section: A Tbc Failuresmentioning

confidence: 81%

“…It has been found that APS TBC failures on NiCoCrAlY bond coats are also influenced by the alloy substrate ( Figure 21). [20] B. Improved TBCs Among various modifications made to EBPVD TBC coated NiCoCrAlY bond coatings, Pt overlayer and the surface polishing resulted in the most significant improvements.…”

Section: A Tbc Failuresmentioning

confidence: 99%

Comparison of the Failures during Cyclic Oxidation of Yttria-Stabilized (7 to 8 Weight Percent) Zirconia Thermal Barrier Coatings Fabricated via Electron Beam Physical Vapor Deposition and Air Plasma Spray

Yanar

Helminiak

Meier

et al. 2010

Metall Mater Trans A

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“…Air plasma spraying (APS) is one of the most widely used thermal spraying techniques for surface treatment because of its low cost and high quality of prepared coatings (Ref 6). APS is widely used in manufacturing coatings, such as thermal barrier (Ref 7,8), corrosion resistance (Ref 3), and abrasive resistance coatings (Ref 9). In particular, the Ni-Cr-B-Si colmonoy alloys are the most commonly applied nickel-base self-fluxing alloys, from which a series of alloys with different hardness can be obtained via adjusting the content of each element.…”

Section: Introductionmentioning

confidence: 99%

Corrosion Behavior of Thermally Sprayed NiCrBSi Coating on 16MnR Low-Alloy Steel in KOH Solution

Zeng

Sun

Emori

et al. 2016

J. of Materi Eng and Perform

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NiCrBSi coatings were selected as protective material and air plasma-sprayed on 16MnR low-alloy steel substrates. Corrosion behavior of 16MnR substrates and NiCrBSi coatings in KOH solution were evaluated by polarization resistance (R p ), potentiodynamic polarization curves, electrochemical impedance spectroscopy, and immersion corrosion tests. Electrolytes were solutions with different KOH concentrations. NiCrBSi coating showed superior corrosion resistance in KOH solution compared with the 16MnR. Corrosion current density of 16MnR substrate was 1.7-13.0 times that of NiCrBSi coating in the given concentration of KOH solution. By contrast, R p of NiCrBSi coating was 1.2-8.0 times that of the substrate, indicating that the corrosion rate of NiCrBSi coating was much lower than that of 16MnR substrate. Capacitance and total impedance value of NiCrBSi coating were much higher than those of 16MnR substrate in the same condition. This result indicates that corrosion resistance of NiCrBSi coating was better than that of 16MnR substrate, in accordance with polarization results. NiCrBSi coatings provided good protection for 16MnR substrate in KOH solution. Corrosion products were mainly Ni/Fe/Cr oxides.

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“…Spallation was linked to the coefficient of thermal expansion (CTE) mismatch between the YSZ TBC and the superalloy substrate where the CTE of IN718 was the largest, followed by HA188 and then René N5 [3,4].…”

Section: Introductionmentioning

confidence: 99%

“…Upon oxidation, these rough surfaces result in non-uniform TGO growth and lead to the formation of non-protective oxides which can cause coating failure [9 -18]. The bond coats employed in the previous work [3,4] had a rough surface (R a ¼ 10:1 mm) and also contained a significant number of pores which were surface connected. This lead to rapid aluminum depletion in the bond coat since there was such a large amount of surface area exposed to the air which could form a TGO.…”

Section: Introductionmentioning

confidence: 99%

The effect of superalloy substrate on the behaviour of high-purity low-density air plasma sprayed thermal barrier coatings

Helminiak

Yanar

Pettit

et al. 2012

Materials at High Temperatures

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Several superalloy-bond coat couples were prepared without ceramic topcoat layers to better understand the effects of superalloy substrate on the oxidation behaviour of NiCoCrAlY bond coats. The same composition NiCoCrAlY bond coats were deposited on three superalloy substrates (Inconel 718, Haynes 188 and René N5) via argon-shrouded plasma spraying. The specimens were exposed to cyclic oxidation in laboratory air at 1100 C in a bottom loading furnace. Scaling behaviour and rate of aluminum depletion were compared between the various specimens. The bond coats on all three superalloys experienced some form of chemical failure after an extended number of cycles. The number of cycles until chemical failure was shortest for the IN718 specimen followed by the HA188 specimen, both of which experienced complete bond coat chemical failure, and then the René N5 specimen, which experienced localized chemical failure. The cycles to chemical failure coincide with the cycles to thermal barrier coating (TBC) spallation from previous work, indicating chemical failure of the bond coat is a critical event in the lifetime of TBCs. The effect of bond coat surface finish and porosity on the scaling behaviour has been investigated using specimens with the same superalloy substrate but with different bond coat surface finishes and porosity levels which were produced by utilizing two separate sized starting bond coat metallic powders. Bond coats with minimal porosity and smooth surface finishes did not experience chemical failure, at least in the time frame they were tested; however, oxide scale spallation was more apparent in the smooth bond coats as compared to the specimens with the rough surface finishes and high levels of porosity.

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The behavior of high-purity, low-density air plasma sprayed thermal barrier coatings

Cited by 34 publications

References 9 publications

Comparison of the Failures during Cyclic Oxidation of Yttria-Stabilized (7 to 8 Weight Percent) Zirconia Thermal Barrier Coatings Fabricated via Electron Beam Physical Vapor Deposition and Air Plasma Spray

Comparison of the Failures during Cyclic Oxidation of Yttria-Stabilized (7 to 8 Weight Percent) Zirconia Thermal Barrier Coatings Fabricated via Electron Beam Physical Vapor Deposition and Air Plasma Spray

Corrosion Behavior of Thermally Sprayed NiCrBSi Coating on 16MnR Low-Alloy Steel in KOH Solution

The effect of superalloy substrate on the behaviour of high-purity low-density air plasma sprayed thermal barrier coatings

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