Influence of the oxide scale features on the electrochemical descaling and stripping of aluminide coatings

Guével, Y. Le; Grégoire, Benjamin; Bouchaud, B.; Bilhé, Pascal; Pasquet, A.; Thiercelin, M.; Pedraza, F.

doi:10.1016/j.surfcoat.2016.03.019

Cited by 16 publications

(6 citation statements)

References 23 publications

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“…In SSP1, retrofitting old plants by de-coating them and applying the new coating is assumed possible. In fact, gas turbine blades can be de-coated and recoated with minimum disruptions [59]. Besides, geographical constraints apply to the wind turbines, where innovative SE is used in northern countries where icing on the turbines increases downtimes in winter.…”

Section: Penetration Of Innovative Surface Engineering Technologies I...mentioning

confidence: 99%

Investigating the role of surface engineering in mitigating greenhouse gas emissions of energy technologies: An outlook towards 2100

Kaddoura

Majeau‐Bettez

Amor

et al. 2022

Sustainable Materials and Technologies

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Section: Penetration Of Innovative Surface Engineering Technologies I...mentioning

confidence: 99%

Investigating the role of surface engineering in mitigating greenhouse gas emissions of energy technologies: An outlook towards 2100

Kaddoura

Majeau‐Bettez

Amor

et al. 2022

Sustainable Materials and Technologies

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“…On the other hand, such a combination of acids should be safe for the surfaces of substrates. Considering the requirements above, many acids and inorganic reagents, such as (NH 4 ) 6 Mo 7 O 24 , HNO 3 , HF and HCl, and their combinations, have been adopted [11][12][13][14]. Poupard et al investigated various soft chemical stripping methods and found that chemical baths containing relatively high concentrations of pitting reagents in organic media are the most effective [15].…”

Section: Introductionmentioning

confidence: 99%

In-Depth Understanding of the Chemical Stripping Mechanism of AlSiY Coatings on Nickel Superalloys by First-Principles Calculation

Li,

Luo,

Zhang

et al. 2024

Coatings

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In order to repair a failed AlSiY coating on aeroengine turbine components, the AlSiY coating was stripped using a nitric acid-based removal reagent. The homogeneity of chemical stripping was evaluated and the stripping mechanism was clarified using first-principles calculations. The effects of hydrofluoric acid (HF) and chromium trioxide (CrO3) on the homogeneity of chemical stripping were investigated by calculating the electronic work functions (EWFs) of the stripped surfaces. The results showed that the stripped surfaces of the AlSiY coating exhibited a serrated appearance when it was etched by a single nitric acid solution, indicating severely inhomogeneous stripping. With the addition of HF and/or CrO3, the homogeneity of chemical stripping could be greatly improved, which was attributed to the increased EWF of the (200) surface and the decreased EWF of the (110) surface, causing the corrosion cathode to transition from the (110) surface to the (200) surface. The HF+CrO3+HNO3 mixed reagent was the optimal combination for the uniform stripping of the AlSiY coating, while the inner layer was not broken. The Al atoms on the surface could be preferentially removed due to the strong bonding with acid ions. The research method proposed in the present work will provide a new means to design chemical removal reagents.

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“…TBC removal technique could be roughly divided into two categories: physical removal technologies [16,17], e.g., sandblasting, grinding, polishing, and machining, and chemical removal technologies [18,19], e.g., soft chemical stripping and electrochemical method. TBC is difficult to be completely removed through physical technology due to process characteristics, and strong mechanical impact will exert intense local stress and deformation on metallic components [20,21]. This contradicts the purpose of the refurbished TBC, which is to protect and reuse higher-value metallic components.…”

Section: Introduction mentioning

confidence: 99%

Comparative study on microstructure evolution and failure mechanisms of ordinary and refurbished EB-PVD TBC under cyclic oxidation

Li¹,

Jin²,

Lü³

et al. 2023

Journal of Advanced Ceramics

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Refurbishment of thermal barrier coating (TBC) has become a valuable technique to prolong the service life of high-temperature components. This study investigates the effect of the refurbishment process (coating removal and recoating) on the microstructure evolution and physical properties of TBC, including oxidation characteristics, element diffusion behavior, and crack failure mechanisms. The results showed that a certain amount of interdiffusion zone (IDZ) with Cr-rich would be retained in DD6 superalloy substrate after coating removal. The microstructure of the refurbished specimens showed equiaxed β-NiAl phases, while the ordinary specimens have elongated grain shapes with a high aspect ratio. Moreover, mixed oxides in the refurbished TBC specimens were earlier observed during cyclic oxidation, with a greater thickness compared to ordinary TBC, due to the influence of BC layer phase sizes. The growth mechanism of thermally grown oxide (TGO-Al 2 O 3 layer) in the refurbished TBC specimens was also different, resulting from the different mechanisms of mixed oxides growth. Furthermore, under cyclic oxidation with water quenching at 1100 ℃, the cracks in the refurbished specimen tend to occur in the mixed oxides layer, while the cracks in the ordinary specimen occur in the top coat (TC) layer, attributing to the earlier and thicker mixed oxides layer formed in refurbished specimens.

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Influence of the oxide scale features on the electrochemical descaling and stripping of aluminide coatings

Cited by 16 publications

References 23 publications

Investigating the role of surface engineering in mitigating greenhouse gas emissions of energy technologies: An outlook towards 2100

Investigating the role of surface engineering in mitigating greenhouse gas emissions of energy technologies: An outlook towards 2100

In-Depth Understanding of the Chemical Stripping Mechanism of AlSiY Coatings on Nickel Superalloys by First-Principles Calculation

Comparative study on microstructure evolution and failure mechanisms of ordinary and refurbished EB-PVD TBC under cyclic oxidation

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