Columnar suspension plasma sprayed coating microstructural control for thermal barrier coating application

Abstract A traditional plasma spray gun consists of an anode and a cathode. During spraying small particles of anode material of either copper or tungsten, depending on the brand of the gun, will be worn off and deposited in the coating. The size and frequency of the particles from a copper anode has generally a dramatic appearance (in the beginning or at the end of its life) whereas a tungsten nozzle normally behaves more randomly during its life. Tungsten particles can therefore be expected anywhere in a plasma sprayed coating. Unfortunately the material properties of tungsten is not very compatible with a thermal barrier coating of partially stabilized zirconia and it is shown that a contamination will cause a catastrophic failure, if located in, for a thermal barrier, a critical region. The behavior of tungsten at elevated temperatures is investigated and clearly show the detrimental effect of tungsten on the life and performance of a thermal barrier coating.

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HOT CORROSION OF CERIA-YTTRIA STABILIZED ZIRCONIA PLASMA SPRAYED THERMAL BARRIER COATING BY EUTECTIC VANDIUM PENTAOXIDE-SODIUM SULFATE

THE IRAQI JOURNAL FOR MECHANICAL AND MATERIALS ENGINEERING ◽

10.32852/iqjfmme.vol18.iss1.83 ◽

2018 ◽

Vol 18 (1) ◽

pp. 182-192 ◽

Cited By ~ 1

Author(s):

Mohammed J Kadhim ◽

Mohammed H Hafiz ◽

Maryam A Ali Bash

Keyword(s):

Thermal Barrier Coating ◽

Hot Corrosion ◽

Monoclinic Phase ◽

Volume Fraction ◽

High Volume ◽

Thermal Barrier ◽

Air Plasma ◽

Plan View ◽

Barrier Coating ◽

Plasma Sprayed

The high temperature corrosion behavior of thermal barrier coating (TBC) systemconsisting of IN-738 LC superalloy substrate, air plasma sprayed Ni24.5Cr6Al0.4Y (wt%)bond coat and air plasma sprayed ZrO2-20 wt% ceria-3.6 wt% yttria (CYSZ) ceramic coatwere characterized. The upper surfaces of CYSZ covered with 30 mg/cm2 , mixed 45 wt%Na2SO4-55 wt% V2O5 salt were exposed at different temperatures from 800 to 1000 oC andinteraction times from 1 up to 8 h. The upper surface plan view of the coatings wereidentified for topography, roughness, chemical composition, phases and reaction productsusing scanning electron microscopy, energy dispersive spectroscopy, talysurf, and X-raydiffraction. XRD analyses of the plasma sprayed coatings after hot corrosion confirmed thephase transformation of nontransformable tetragonal (t') into monoclinic phase, presence ofYVO4 and CeVO4 products. Analysis of the hot corrosion CYSZ coating confirmed theformation of high volume fraction of YVO4, with low volume fractions of CeOV4 and CeO2.The formation of these compounds were combined with formation of monoclinic phase (m)from transformation of nontransformable tetragonal phase (t').

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Plasma Sprayed Lanthanum Zirconate Coating over Additively Manufactured Carbon Nanotube reinforced Ni-based Composite: Unique performance of Thermal Barrier Coating System without Bondcoat

Applied Surface Science ◽

10.1016/j.apsusc.2021.149397 ◽

2021 ◽

pp. 149397

Author(s):

Sumit Choudhary ◽

Aminul Islam ◽

Biswajyoti Mukherjee ◽

Julia Richter ◽

Tizian Arold ◽

...

Keyword(s):

Carbon Nanotube ◽

Thermal Barrier Coating ◽

Thermal Barrier ◽

Coating System ◽

Lanthanum Zirconate ◽

Thermal Barrier Coating System ◽

Barrier Coating ◽

Plasma Sprayed

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Measurements of elastic modulus and fracture toughness of an air plasma sprayed thermal barrier coating using micro-cantilever bending

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2019.05.031 ◽

2019 ◽

Vol 374 ◽

pp. 12-20 ◽

Cited By ~ 4

Author(s):

Ying Chen ◽

Xun Zhang ◽

Xiaofeng Zhao ◽

Nicolaie Markocsan ◽

Per Nylén ◽

...

Keyword(s):

Fracture Toughness ◽

Elastic Modulus ◽

Thermal Barrier Coating ◽

Thermal Barrier ◽

Air Plasma ◽

Barrier Coating ◽

Micro Cantilever ◽

Cantilever Bending ◽

Plasma Sprayed

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The crack number density theory on air-plasma-sprayed thermal barrier coating

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2018.11.058 ◽

2019 ◽

Vol 358 ◽

pp. 347-352 ◽

Cited By ~ 5

Author(s):

X.J. Wu

Keyword(s):

Thermal Barrier Coating ◽

Thermal Barrier ◽

Number Density ◽

Air Plasma ◽

Barrier Coating ◽

Plasma Sprayed

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Oxygen Transport Through the Zirconia Top Coat in Thermal Barrier Coating Systems

Thermal Spray 1998: Proceedings from the International Thermal Spray Conference ◽

10.31399/asm.cp.itsc1998p1589 ◽

1998 ◽

Author(s):

A.C. Fox ◽

T.W. Clyne

Keyword(s):

Thermal Barrier Coating ◽

Bond Coat ◽

Ionic Conduction ◽

Gas Permeability ◽

Gas Permeation ◽

Thermal Barrier ◽

Barrier Coating ◽

Oxygen Gas ◽

Plasma Sprayed ◽

Tbc Systems

Abstract The gas permeability of plasma sprayed yttria-stabilised zirconia coatings has been measured over a range of temperature, using hydrogen and oxygen gas. The permeability was found to be greater for coatings produced with longer stand-off distances, higher chamber pressures and lower torch powers. Porosity levels have been measured using densitometry and microstructural features have been examined using SEM. A model has been developed for prediction of the permeability from such microstructural features, based on percolation theory. Agreement between predicted and measured permeabilities is good. Ionic conduction through the coatings has also been briefly explored. It is concluded that transport of oxygen through the top coat in thermal barrier coating (TBC) systems, causing oxidation of the bond coat, occurs primarily by gas permeation rather than ionic conduction, at least up to temperatures of about 1000°C and probably up to higher temperatures. Top coat permeabilities appreciably below those measured will be required if the rate of bond coat oxidation is to be reduced by cutting the supply of oxygen to the interface.

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