An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy

Chen, Hao; Si, Yi; McCartney, D.G.

doi:10.1016/j.jallcom.2017.02.002

Cited by 32 publications

(7 citation statements)

References 66 publications

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“…13 shows the nearly globular morphology and irregular shapes of the β phase, indicating a large surface energy. A previous β-phase coarsening study has revealed that the γ/β interface in MCrAlY-8 exhibits large interfacial energies (>200 mJ/m 2 ) at temperatures above 1000 °C [42]. Rapid dissolution of the β phase may occur when the temperature increases in order to minimise the interfacial energy of the system.…”

Section: Effects Of Temperaturementioning

confidence: 96%

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Effects of temperature on the β-phase depletion in MCrAlYs: A modelling and experimental study towards designing new bond coat alloys

Chen

Rushworth

Hou

et al. 2019

Surface and Coatings Technology

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This paper investigates the effects of varied temperature conditions on the kinetics of β-phase depletion in MCrAlYs by DICTRA diffusion simulations and experimental observations. A commercially available MCrAlY composition and two modelled compositions were examined at temperature regimes of 1000 °C, 1100 °C and 1200 °C. A previously developed temperature-dependent oxidation model was used at the boundary to examine the β-phase depletion kinetics at different temperatures. The oxide growth kinetics and the corresponding Al flux were calculated based on the oxidation model. The MCrAlY phase equilibrium calculations were conducted in Thermo-Calc and the oxidation-diffusion simulations were carried out using the finite difference diffusion software, DICTRA. It was found that the MCrAlYs exhibit a predominantly dual-phase γ+β structure at 1000 °C and above. It was revealed that varying the temperature had a strong effect on the β-phase depletion in low Alcontent MCrAlYs from DICTRA simulations and available experimental measurements. In *Manuscript Click here to view linked References addition, it was demonstrated from the diffusion simulations that MCrAlYs with high Al content exhibit an enhanced lifetime in maintaining the two-phase structure with less β-phase depletion at high temperatures due to the high Al and β-phase content.

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Section: Effects Of Temperaturementioning

confidence: 96%

“…$ are the volume fraction of the γ and β phase measured from Fig. 13, and ρ ' and ρ ( are the density of the γ and β phase, taken as 7.83×10 3 kg/m 3 and 6.81×10 3 kg/m 3 respectively [42]. The converted mass fraction from the measured volume fraction is thus plotted in Fig.…”

Section: Experimental Validationmentioning

confidence: 99%

Effects of temperature on the β-phase depletion in MCrAlYs: A modelling and experimental study towards designing new bond coat alloys

Chen

Rushworth

Hou

et al. 2019

Surface and Coatings Technology

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“…The thermal barrier coating consists of two parts: a ceramic thermal barrier coating and a bond coat. MCrAlY (M = Ni, Co, NiCo) coatings have been widely used as a bond coat for thermal barrier coatings or as a high-temperature protective coating alone [1][2][3][4][5][6][7][8]. The advantages of MCrAlY coatings have been researched by Saeidi et al [6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Vacuum Heat Treatment on the High-Temperature Oxidation Resistance of NiCrAlY Coating

Zheng¹,

Yang²,

Gao³

2020

Coatings

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NiCrAlY coatings were prepared using high-velocity oxygen fuel spraying (HVOF), and the coatings were removed from the substrate to achieve a uniform shape. Vacuum heat treatment (VHT) of the as-sprayed coatings was conducted at different temperatures (1000, 1100, and 1200 °C), and the specimens were subjected to isothermal oxidation exposure testing in air at 1100 °C for up to 21 h. The results show that the high temperature oxidation resistance of the coating increased gradually with the increase in VHT temperature, and the coating of VHT1200 had higher oxidation resistance. The high temperature oxidation resistance of the coating was related to the microstructure transformation of the coating. In VHT coatings, β-NiAl became a dispersed irregular block morphology. The γ’-Ni3Al in VHT1000 presented a granular morphology. However, in VHT1100 and VHT1200, γ’-Ni3Al became a lamellar morphology. This transformation of microstructure promotes the form of exclusive α-Al2O3 scale. With the increase in VHT temperature, the content of yttrium on coatings’ surface was increased and the pores were gradually eliminated. The concentration of yttrium on coatings’ surface prevented the formation of θ-Al2O3 and low porosity was beneficial in improving the internal oxidation of the coating.

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“…pores, oxide inclusions and un-melted particles [39,40]. This means the coatings generally exhibit quite different structures and properties than the cast alloys of the same chemistry [41,42]. The defects embedded in the coatings can have a significant influence on their mechanical response during the SPT.…”

Section: Introductionmentioning

confidence: 99%

Some considerations in using the small punch testing for thermally sprayed CoNiCrAlY coatings

Chen

Rushworth

Sun

et al. 2019

Surface and Coatings Technology

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Small punch testing exhibits great potential in mechanical characterisation of thin coatings.This testing method can be used to determine the mechanical performance of thermally sprayed coatings, especially to qualitatively characterise the effects of coating defects on the mechanical behaviour. In this work, some considerations in using the small punch testing for coatings are presented through a microstructure evolution analysis of a vacuum plasma sprayed CoNiCrAlY coating under small punch test. The CoNiCrAlY coating was characterised with a large number of un-melted particles as the coating defects. It is shown that the clamping in the small punch test rig can result in micro-cracking around the unmelted particles in the coating prior to testing. It is also found that the un-melted particles in the coating act as predominant cracking sites and fast failure occurred around the un-melted particles. Careful considerations need to be taken into account when using the small punch test for coatings to avoid any changes in the coating microstructure and plasticity during the clamping stage.

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An analytical approach to the β-phase coarsening behaviour in a thermally sprayed CoNiCrAlY bond coat alloy

Cited by 32 publications

References 66 publications

Effects of temperature on the β-phase depletion in MCrAlYs: A modelling and experimental study towards designing new bond coat alloys

Effects of temperature on the β-phase depletion in MCrAlYs: A modelling and experimental study towards designing new bond coat alloys

Effect of Vacuum Heat Treatment on the High-Temperature Oxidation Resistance of NiCrAlY Coating

Some considerations in using the small punch testing for thermally sprayed CoNiCrAlY coatings

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