Influence of the surface roughness on the oxide scale formation on MCrAlY coatings studied in situ by high temperature X-ray diffraction

Czech, N.; Juez‐Lorenzo, M.; Kolarik, V.; Werner, Stefan

doi:10.1016/s0257-8972(98)00554-4

Cited by 39 publications

(12 citation statements)

References 12 publications

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“…8 show the variations of the Meier model compared to the other two models used in this study. The parabolic constant obtained from TGA analysis agrees well with other reported work in the literature [51][52][53], with magnitudes between 10 -10 ~ 10 -14 depending on the temperatures used. Since Meier model was based on the as-sprayed surface, the comparisons with other models were conducted under rough surface conditions.…”

Section: Oxide Growth Kineticssupporting

confidence: 90%

Some aspects on modelling of the β-phase depletion behaviour under different oxide growth kinetics in HVOF CoNiCrAlY coatings

Chen

McCartney

2017

Surface and Coatings Technology

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In this paper, β-phase depletion behaviour of free-standing high velocity oxy-fuel (HVOF) thermally sprayed CoNiCrAlY coatings was studied. Microstructural analysis showed a twophase microstructure of γ-Ni matrix and β-NiAl secondary phase after heat treatment. Fine grains were found around the sprayed particle boundaries and coarse grains were retained as the original particle structure, with grain sizes varying from 2 to 0.5 µm or even less for both phases. The β-phase depletion behaviour was investigated during isothermal oxidation and was also modelled through diffusion calculations. A previously developed β-phase depletion model was utilised to study the evolution of β-phase depletion under different oxide growth kinetics. Three oxide growth models were tried: 1) Meier model, 2) thermogravimetric analysis (TGA) model, and 3) experimentally fitted oxide growth model. The oxide growth kinetics were converted to Al flux functions which were used as the boundary conditions in the DICTRA modelling. It is shown that the results obtained from the three models exhibit good agreements between the measured and predicted results for times up to 100 h at 1100 C, but discrepancies were noted at longer oxidation times. Further improvements on closely 2 modelling the oxidation kinetics and the effective diffusion behaviour are needed to minimise the discrepancies at longer oxidation times.

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Section: Oxide Growth Kineticssupporting

confidence: 90%

Some aspects on modelling of the β-phase depletion behaviour under different oxide growth kinetics in HVOF CoNiCrAlY coatings

Chen

McCartney

2017

Surface and Coatings Technology

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“…The surface roughness of the coating increases with increased powder size (Fig. 11), which is consistent with previous observations (Ref [15][16][17]. CO-series coatings have lower surface roughness compared with CONI-series coatings within similar particle size, because of the relatively wellmelted lamellar structure.…”

Section: Cross-sectional Porositysupporting

confidence: 91%

“…It is preferred that this oxide scale be a continuous, dense a-alumina (a-Al 2 O 3 ) layer (Ref 4), since it protects the metallic overlay coating from further oxidation, due to the low diffusivity of oxygen and metallic elements through the a-alumina layer ( Ref 5). However, many factors, such as starting powder (Ref [6][7][8], alloy chemistry (Ref [9][10][11][12], microstructure of the coating (Ref 13,14), surface condition of the deposited coating (Ref [15][16][17], deposition method and its process parameters (Ref [18][19][20] can affect the composition and the structure of the TGO scale that in turn, can greatly affect the performance of the MCrAlY coatings.…”

Section: Introductionmentioning

confidence: 99%

Effect of Particle Size Distribution on Isothermal Oxidation Characteristics of Plasma Sprayed CoNi- and CoCrAlY Coatings

et al. 2007

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The effect of particle size distribution on the degradation behavior of plasma sprayed CoNi-and CoCrAlY coatings during isothermal oxidation was investigated, in terms of the oxygen content, porosity, surface roughness, and oxide scale formation. The results show that the degradation of both coatings was considerably influenced by the starting particle size distribution. It also shows that in the assprayed vacuum plasma spray (VPS) coatings the oxygen content on the coating surface increased significantly with decreased average particle size. But after thermal exposure, the difference of the oxygen contents between the coatings with different particle size was decreased. The powder with various particle size resulted in low porosity inside the coatings during the deposition process. The surface roughness of the coatings increased with increased particle size. The small particles produced a relatively smooth surface, and the oxide growth in the coating deposited by small particle was slower than that in the large particle coating.

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“…Stresses in thin oxide films are difficult to measure and the fracture behavior of alumina scales on overlays is not well understood (Ref 12), mainly due to variations in scale microstructures, flaws, and interfacial adhesion as a function of the substrate chemistry, mechanical properties, and surface condition. In addition, there has been relatively little detailed microstructural investigations of the evolution phenomenon of thermally grown oxide (TGO) accumulation on protective overlay coatings after isothermal oxidation (Ref [13][14][15], because spallation and sintering of the damaged scales often complicates or prevents such an analysis. An improved understanding of the microstructures, flaws, and fracture behavior of Al 2 O 3 scales grown under isothermal conditions must be attained before a basis for the long-term structureproperties relationships of these protective oxide layers can be developed.…”

Section: Introductionmentioning

confidence: 99%

High-temperature Oxidation Behavior and Surface Roughness Evolution of VPS NiCrAlY Coating

et al. 2008

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In this work, as a background to the development of high temperature environmental protection coating technology, the structural transformation of vacuum-plasma sprayed NiCrAlY coating has been studied, including the oxidation behavior, elastic modulus, microhardness, and surface roughness. Coating was oxidized isothermally at a 1,273 K for different time periods up to 1,000 h in order to form the oxide scale layer. The results showed that the oxide scale and weight gain increased proportional to the exposure time. The surface roughness and hardness decreased after isothermal exposure, but they are not proportional to the exposure time. The oxide scale growth was concentrated in the valleys of the surface at the early 1 h exposure (decreasing surface roughness), whereas the oxide scales over a longer perspective (time period), grew on the convex surface (increasing surface roughness).

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Influence of the surface roughness on the oxide scale formation on MCrAlY coatings studied in situ by high temperature X-ray diffraction

Cited by 39 publications

References 12 publications

Some aspects on modelling of the β-phase depletion behaviour under different oxide growth kinetics in HVOF CoNiCrAlY coatings

Some aspects on modelling of the β-phase depletion behaviour under different oxide growth kinetics in HVOF CoNiCrAlY coatings

Effect of Particle Size Distribution on Isothermal Oxidation Characteristics of Plasma Sprayed CoNi- and CoCrAlY Coatings

High-temperature Oxidation Behavior and Surface Roughness Evolution of VPS NiCrAlY Coating

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