Microscopic observation of degradation behavior in yttria and ceria stabilized zirconia thermal barrier coatings under hot corrosion

Park, S.Y.; Kim, J.H.; Kim, M.C.; Song, Homin; Park, C.G.

doi:10.1016/j.surfcoat.2004.04.065

Cited by 151 publications

(60 citation statements)

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“…The failure mechanisms observed in this study are in agreement with those proposed by Park et al [7] that refers three steps for the corrosion mechanism: a first in which the salt penetration into the entire thickness is observed; a second in which the penetrated salts react with the stabilizers of zirconia and; the final is completed by macroscale damage as a consequence of thermal and mechanical stresses that promote gradual losses of material from the surface (see released by detachment of the top coat. In the case of the laser-glazed specimens, since the molten salts may preferably attack the YSZ under the remelted dense layer (Fig.…”

Section: Mechanisms Of Degradationsupporting

confidence: 92%

“…Various studies [3,4,6,7,[13][14][15] with focus on the hot corrosion of YSZ have reported the reaction of yttria, from the zirconia solid solution, with vanadium-containing compounds leading to the formation of yttrium vanadate (YVO 4 ):…”

Section: Mechanisms Of Degradationmentioning

confidence: 99%

“…TBCs have limited applications in industrial gas turbines and diesel engines because the commonly used stabilizers of zirconia react with sulfur, sodium and vanadium contaminants contained in many industrial low-quality fuels [3,6,7]. Furthermore, particularly in plasmasprayed coatings, the penetration of these contaminants through the porous and microcracked coating may also attack the underlying metallic components by hot corrosion mechanisms.…”

Section: Introductionmentioning

confidence: 99%

“…Hot corrosion can be defined as accelerated corrosion that results from the presence of salt contaminants such as Na 2 SO 4 , NaCl and V 2 O 5 which form molten deposits that react with the protective oxide coatings [7,8]. Laser-glazing has been mentioned by Jones [3] and Gurrappa [6], as an approach to improve the hot corrosion resistance of zirconia-based thermal barrier coatings by preventing salt penetration into the coating.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of laser-glazed plasma-sprayed thermal barrier coatings under high temperature exposure to molten salts

Batista

Portinha

Ribeiro

et al. 2006

Surface and Coatings Technology

126

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Thermal Barrier Coating (TBC) systems are frequently used in gas turbine engines to provide thermal insulation to the hot-section metallic components and also to protect them from oxidation, hot corrosion and erosion. Surface sealing treatments, namely laser-glazing, have been showing a high potential for extending in-service lifetimes of these systems by improving chemical and thermo-mechanical resistance. In this investigation, both as-sprayed and laserglazed TBCs were exposed to hot corrosion in molten salts. The glazed coatings were obtained by scanning the surface of the plasma-sprayed coatings with either a CO 2 or a Nd:YAG laser.The hot corrosion investigation was accomplished by subjecting the specimens to an isothermal air furnace testing under V 2 O 5 and/or Na 2 SO 4 in a temperature of 1000ºC for 100 hours.Spallation has been observed in coatings in the as-sprayed condition under V 2 O 5 or -2 -V 2 O 5 +Na 2 SO 4 . Na 2 SO 4 itself had no or minimal effect on the degradation of the laser-glazed or as-sprayed condition coatings, respectively. The degradation in V 2 O 5 was accomplished by destabilization of YSZ as a consequence of depletion of yttria from the solid solution to form YVO 4 and therefore led to the disruptive transformation of the metastable tetragonal phase to the monoclinic phase. Moreover, the presence of both corrosive salts induced the formation of large high aspect ratio YVO 4 crystals that introduced additional stresses and contributed to the degradation of the coatings. The laser-glazed specimens were not efficient in avoiding the molten salt penetration along the thickness direction due to the presence of cracks on the glazed layer.However due to a reduced specific surface area of the dense glazed layer, the corrosion reaction of the molten salts with the YSZ has been lower than in coatings in the as-sprayed condition.-3 -

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Section: Mechanisms Of Degradationsupporting

confidence: 92%

Section: Mechanisms Of Degradationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Evaluation of laser-glazed plasma-sprayed thermal barrier coatings under high temperature exposure to molten salts

Batista

Portinha

Ribeiro

et al. 2006

Surface and Coatings Technology

126

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“…The tests reported in the literature have been conducted from 700 o C to about 1050 o C using different salt concentrations, with a majority of the tests focused on YSZ thermal barrier coatings. Limited research on the corrosion mechanism of other top coat materials such as gadolinium zirconate [48,49,55], ceria-stabilized zirconia [56][57][58], titaniastabilized zirconia [58], scandia and yttria co-stabilized zirconia [59] and zirconia-alumina [54] have been reported as well.…”

Section: Hot Corrosion Tests -Failure Mechanismsmentioning

confidence: 99%

Failure mechanisms in APS and SPS thermal barrier coatings during cyclic oxidation and hot corrosion

Jonnalagadda¹

2017

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Linköping 2017Front page image: The top view of yttria stabilized zirconia thermal barrier coating after exposure to a salt mixture of vanadium pentoxide and sodium sulfate at 900 o C.During the course of research underlying this thesis, Krishna Praveen Jonnalagadda was enrolled in Agora Materiae, a multidisciplinary doctoral program at Linköping University, Sweden.ISBN: 978-91-7685-594-2 ISSN: 0280-7971Printed by LiU-Tryck 2017 iii AbstractThermal Barrier Coatings (TBCs) are advanced material systems that are being used in the hot sections of gas turbines such as combustor, turbine blades, and vanes. The top ceramic coating in TBCs provides insulation against the hot gases and the intermediate metallic bond coat provides oxidation and corrosion resistance to the underlying turbine components.Durability of thermal barrier coatings is very important for the overall performance of the gas turbine. TBCs can fail in several different ways and there is a combination of more than one failure mechanism in most situations. One of the most widely used TBC is atmospheric plasma sprayed (APS) yttria stabilized zirconia (YSZ). Both the deposition technique and the TBC material have certain limitations. The main aim of this research is to study new TBC materials and/or new deposition techniques and compare with the conventional YSZ and understand their failure mechanisms during cyclic oxidation and hot corrosion.Thermal cyclic oxidation of a newly developed high purity nano YSZ thermal barrier coating has been studied. Cross sectional analysis of exposed as well as completely failed samples showed a mixed-type failure caused by crack propagation parallel to the bond coat/top coat interface. The majority of the damage occurred towards the end of the coating life. A finite element model has been developed to study the probability of crack growth along different paths that leads to the final failure.Hot corrosion mechanism in suspension plasma sprayed two-layer gadolinium zirconate/YSZ, three-layer dense gadolinium zirconate/gadolinium zirconate/YSZ, and a single-layer YSZ has been studied in the presence of sodium sulfate and vanadium pentoxide. The test results showed that gadolinium zirconate coatings were more susceptible to corrosion compared to YSZ coatings despite gadolinium zirconate coatings having lower reactivity with the corrosive salts.Thermal cycling behavior of a high chromium bond coat has been studied. Cross-sectional analysis showed formation of sandwich type microstructure with chromium rich oxide and alumina as the top and the bottom layers.Inter-diffusion of minor elements between different MCrAlY coatings -substrate systems has been studied using, diffusion simulation software, DICTRA. The simulation results showed that the diffusion of minor elements in the coatings is dependent on the rate of β phase depletion in the beginning. After the depletion of β phase there was no clear dependence of the coating composition on the diffusion of minor elements.v SammanfattningTermiska barriärskikt, eller TBC från...

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An Investigation on Hot Corrosion Resistance of Plasma Sprayed YSZ‐Ceria TBC in Na ₂ SO ₄ +V ₂ O ₅ at 1050°C

Saremi¹,

Habibi²

2011

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Microscopic observation of degradation behavior in yttria and ceria stabilized zirconia thermal barrier coatings under hot corrosion

Cited by 151 publications

References 15 publications

Evaluation of laser-glazed plasma-sprayed thermal barrier coatings under high temperature exposure to molten salts

Evaluation of laser-glazed plasma-sprayed thermal barrier coatings under high temperature exposure to molten salts

Failure mechanisms in APS and SPS thermal barrier coatings during cyclic oxidation and hot corrosion

An Investigation on Hot Corrosion Resistance of Plasma Sprayed YSZ‐Ceria TBC in Na ₂ SO ₄ +V ₂ O ₅ at 1050°C

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Microscopic observation of degradation behavior in yttria and ceria stabilized zirconia thermal barrier coatings under hot corrosion

Cited by 151 publications

References 15 publications

Evaluation of laser-glazed plasma-sprayed thermal barrier coatings under high temperature exposure to molten salts

Evaluation of laser-glazed plasma-sprayed thermal barrier coatings under high temperature exposure to molten salts

Failure mechanisms in APS and SPS thermal barrier coatings during cyclic oxidation and hot corrosion

An Investigation on Hot Corrosion Resistance of Plasma Sprayed YSZ‐Ceria TBC in Na 2 SO 4 +V 2 O 5 at 1050°C

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An Investigation on Hot Corrosion Resistance of Plasma Sprayed YSZ‐Ceria TBC in Na ₂ SO ₄ +V ₂ O ₅ at 1050°C