Thermal expansion of vacuum plasma sprayed coatings

Raj, S. V.; Palczer, Anna

doi:10.1016/j.msea.2009.11.064

Cited by 11 publications

(3 citation statements)

References 16 publications

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“…• C) [8,22] and will cause additional internal stresses and lower the resulting CTE of the alloy due to mixture rules. For further alloy development, it might be therefore necessary to reduce the amount of β and α-phase.…”

Section: Increasing Cu-contentmentioning

confidence: 99%

Design of a Nickel-Based Bond-Coat Alloy for Thermal Barrier Coatings on Copper Substrates

Fiedler

Федорова

Rösler

et al. 2014

Metals

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To increase the lifetime of rocket combustion chambers, thermal barrier coatings (TBC) may be applied on the copper chamber wall. Since standard TBC systems used in gas turbines are not suitable for rocket-engine application and fail at the interface between the substrate and bond coat, a new bond-coat material has to be designed. This bond-coat material has to be chemically compatible to the copper substrate to improve the adhesion and needs a coefficient of thermal expansion close to that of copper to reduce thermal stresses. One approach to achieve this is to modify the standard NiCrAlY alloy used in gas turbines by adding copper. In this work, the influence of copper on the microstructure of NiCrAlY-alloys is investigated with thermodynamical calculations, optical microscopy, SEM, EDX and calorimetry. Adding copper leads to the formation of a significant amount of β-NiAl and α-Cr. Reducing the aluminum and chromium content leads furthermore to a two-phase fcc microstructure.

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Section: Increasing Cu-contentmentioning

confidence: 99%

Design of a Nickel-Based Bond-Coat Alloy for Thermal Barrier Coatings on Copper Substrates

Fiedler

Федорова

Rösler

et al. 2014

Metals

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“…A metallic TBC consisting of a NiCrAlY top coating and containing Cu bonding coating has been studied by S.V. Raj [5] and Louis J [6]. Their results showed that NiCrAlY, with low thermal conductivity, exhibited good thermal insulation performance, and can play a role in thermal isolation and combustion chamber protection.…”

Section: Introductionmentioning

confidence: 99%

Microstructural Stability of a Metallic Thermal Barrier Coatings for Rocket Engine

Zhu,

Sun,

Luo

et al. 2023

MSF

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Metallic thermal barrier coatings (TBCs) consisting of a bond coating and a top coating have been extensively utilized for protecting the walls of rocket combustion chambers. However, standard coating systems often encounter failures due to the significant differences in coating composition and thermal expansion coefficient compared to the substrate under high heat flux conditions. To protect liquid rocket combustion chamber walls, a novel metallic multilayer TBC system applied with atmospheric plasma spraying is developed in the present work. It attempted to deposit dense Ni-based alloy and Cu-based bonding coatings with low oxide contents achieved by introducing boron as a deoxidizer element through atmospheric plasma spraying. The structural stability of the TBC was assessed through high temperature thermal exposure experiments, while the thermal cycle life is evaluated using laser thermal shock. Results show that the NiCrCu2B and CuNi2B bonding coatings prepared through in situ deoxygenation effect of boron exhibit dense structures, low oxide content, and excellent bonding quality. The high temperature thermal exposure experiment reveals that the multilayer structural TBC can withstand 850 °C for 10 hours without the formation of Kirkendal effect pores. Moreover, the thermal cycling life results indicate that the multilayer structural TBC designed in this study, employing a composition gradient transition and the in situ deoxygenation effect of boron, possesses a significantly improved thermal cycle lifetime compared to traditional structural TBCs.

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“…Although only single-layer oxide scales have been observed by other researchers [Selvig et al, 2014;Bsat et al, 2018-1], the coating, being based on nickel, can form duallayered oxide scales [Birks et al, 2006], which, if it was the case, would mean that the oxide scale experienced the same stresses as described for the BS specimen (Table 5.1), with NiO forming the outer layer and Cr2O3 formed the inner layer. (Note NiCrAlY CTE at 625 o C: 0.9 % or ~1.0E-05/ o C [Raj & Palczer, 2010] and NiO CTE at 625 o C: ~1.39E-05/ K [Loken et al, 2018]).…”

Section: Cs Specimensmentioning

confidence: 98%

Oxidation Study of Incoloy 800H Tubes Exposed to Super-Heated Steam and Supercritical Water

Nazarali

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Incoloy 800H, a high-nickel austenitic alloy, has great merit for use in Supercritical Water (SCW). The development of the CANada Deuterium Uranium (CANDU) nuclear Supercritical Water Reactor (SCWR) was the driving force behind this research to investigate the oxidation performance of Incoloy 800H for use as fuel cladding.The oxidation behaviour of Incoloy 800H was investigated in Super-Heated Steam (SHS) (625 o C, 0.1 MPa) for a duration of 500 hours and, again, for 1,000 hours, and in SCW (625 o C, 26.14 MPa) for 500 hours using novel tube specimens. Four specimen configurations were prepared to have a combination of Open-Ends (OE) or Closed-Ends (CE) with either a Bare Surface (BS) or a NiCrAlY Coated Surface (CS). The OE and CE specimens experienced different through-thickness stress distributions due to their testing environment, which allowed comparison and characterization of their performance with regard to oxidation and stress.Standard mass and dimension change measurements performed on the test specimens were observed to be unreliable for characterizing the relative oxidation between different test environments and specimen configurations. Detailed metallographic studies were made with the aid of optical microscopy, Scanning Electron Microscopy (SEM), Energy Dispersion Spectrometry (EDS), and X-Ray Diffraction (XRD), in addition to mass and dimensional measurements. Finite Element Analysis (FEA) was performed to determine the effect that specimen configuration and testing environment have on the stress distributions within the specimens.Testing showed that BS specimens in SHS and SCW produced sufficiently similar oxidation behaviours and oxide scales; spallation of the outer Fe-rich oxide layer was believed to have occurred. The CS specimens formed a thin and discontinuous oxide under both SHS and SCW. The CE/BS tube yielded and collapsed when exposed to SCW with iv cracks and 'folds' vulnerable to oxidation forming on the collapsed surfaces. The NiCrAlY coating provided sufficient strength to reinforce the CE/CS tube preventing its collapse in SCW conditions.From the perspective of oxidation performance, it has been determined that SHS (625 o C, 0.1 MPa) is a suitable medium for investigating the oxidation behaviour of Incoloy 800H in SCW (625 o C, 26.14 MPa) and would provide comparatively conservative results.The coating affords the tube additional protection from both oxidation and stress, providing the potential of extending the operating life of the Incoloy 800H tubes. v I am grateful for the support and expertise of

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Thermal expansion of vacuum plasma sprayed coatings

Cited by 11 publications

References 16 publications

Design of a Nickel-Based Bond-Coat Alloy for Thermal Barrier Coatings on Copper Substrates

Design of a Nickel-Based Bond-Coat Alloy for Thermal Barrier Coatings on Copper Substrates

Microstructural Stability of a Metallic Thermal Barrier Coatings for Rocket Engine

Oxidation Study of Incoloy 800H Tubes Exposed to Super-Heated Steam and Supercritical Water

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