CE08 - Matériaux métalliques et inorganiques et procédés associés

Corrosive-Oxidative coupled Mechanical Performances of materials Assessed via Advanced Characterization Tools – COMPAACT

COMPAACT: Corrosive-Oxidative coupled Mechanical Performances of materials Assessed via Advanced Characterization Tools

Corrosive-Oxidative coupled Mechanical Performances of materials Assessed via Advanced Characterization Tools

Toward a better understanding of surface effects of structural materials exposed at high temperature in oxidative atmosphere: mechanochemical behavior of small-sized samples

In many industrial applications, structural materials subjected to severe environments at high temperatures (650°C – 1100°C) are<br />prone to premature damage due to local oxidation-corrosion-assisted deformation. COMPAACT is a fundamental and experimental<br />project proposing to tackle the influence of multi-physics coupling on the local and time-evolving properties of the surface and<br />sub-surface and its effect on the overall component response. The joint expertise of ICA consortium and the project bearer enables<br />the innovative development of an in-situ versatile mechanical test rig capable to simultaneously correlate the multi-scale<br />deformation of materials to the surface reactivity at high temperatures in various atmospheric conditions. The scientific challenges<br />addressed in this project will trigger novel understanding and prediction of in-service corrosion issues in surface engineering, but<br />also strengthen the capabilities of materials processing technologies in structural applications.

- Develop a specific precision jig to obtain samples of the µm but centimetre size;
- Study the phenomenon of generalized and localized breakaway during high-temperature oxidation in the presence or absence of mechanical loading;
- To develop a high-temperature chamber under a controlled atmosphere allowing the study of the surface reactivity associated with the deformation field.

- Design, manufacture, demonstration, and validation of the specific precision jig to obtain samples of the µm but centimetre size (better stability, reduction of the minimum sample thickness from 15 to 8 µm, smaller thickness variation during sample preparation).
- Study of the mechanisms and kinetics of high-temperature oxidation of Ni-based coatings and superalloys using different thicknesses: Demonstration of the thickness/temperature/time ratio for the activation of the generalized breakaway.
- Study of the local and generalized surface reactivity affected by external mechanical stress (cyclic or static loading) on the surface reactivity of Ni-based superalloys of different thicknesses.
- Capture the onset of microstructural strain localization due to external mechanical stress (cyclic or static loading) and relate it to local surface reactivity.
- Spatial and temporal spectroscopic characterization of surface reactivity events on samples.
- Development of a high-temperature chamber under a controlled atmosphere allowing kinematic and spectroscopic measurements at small scales at high temperature.

- To develop a test bench allowing photomechanical testing at high temperature and on small scales to study the oxidation mechanisms assisted by high-temperature deformation at the microstructure scale.

[1] Texier, D., Copin, E., et al. High temperature oxidation of NiCrAlY coated Alloy 625 manufactured by selective laser melting. Surf Coat Technol (2020), in press

[2] Texier, D., Cadet, C., Straub, T. et al. Tensile Behavior of Air Plasma Spray MCrAlY Coatings: Role of High Temperature Agings and Process Defects. Metall and Mat Trans A 51, 2766-2777 (2020). doi.org/10.1007/s11661-020-05722-3

[3] Cadet, C., Straub, T. Texier, D. et al. Tensile behavior of air plasma spray MCrAlY coatings: Role of high temperature aging and process defect, in: ICMCTF 2019, poster à une conference internationale (2018) San Diego (USA)

[4] Texier, D. et al. Essais micromécanique pour des caractérisations mésoscopiques
et essais macromécanique pour des caractérisations microscopiques à haute températures, in : Séminaire invité LSPM (2019) Paris (France)

[5] Texier, D. La micromécanique haute température pour le couplage «oxidation-diffusion-mécanique« in : Séminaire invité GdR COnCOrD (2019) Compiègne (France)

[6] Javaudin, B., Ecochard, M., Gilblas, R. et al. Suivi in-situ de l'oxydation d'un rev$ecirc;tement MCrAlY par thermoréflectométrie proche infrarouge in : Poster conférence nationale SFT (2019) Nantes (France)

[7] Texier, D., Sirvin, Q. Velay, V. et al. Oxygen/nitrogen-assisted degradation of the mechanical behavior of titanium alloys exposed at elevated temperature, in: Titanium 2018, présentation à une conference internationale (2019) Nantes (France)

In many industrial applications (power plants, aeronautic turbines, etc.), structural materials subjected to severe environments at high temperatures (650°C – 1200°C) are prone to premature damage due to local oxidation/corrosion-assisted deformation but also deformation-assisted surface reactivity. Such degradations alter the surface of the materials and their bulk properties due to a progressive selective consumption of reactive elements involved in the surface reaction. The material in a shallow region beneath the reactive surface subsequently shows a gradient in chemical composition, microstructure and physical properties. Despite the negligible scale of those gradients (from micrometers to hundreds of micrometers beneath the surface) as compared to the structural component dimensions, the variability of the mechanical behavior within the gradient often drives premature damage and the progressive rupture of the component. The quantitative evaluation of the time-evolving properties within the graded material is not trivial to assess due to scale, especially at high temperature. However, such local data are compulsory for a better understanding and prediction of those premature damages.
The COMPAACT project is a fundamental and experimental project proposing to tackle the intricate influence of multi-physics coupling on the local and time-evolving properties of the surface and the sub-surface materials and its effect on the overall component response. Ni-based superalloys and protective coatings will be purposely investigated. In order to achieve this, COMPAACT aimed at developing an innovative and versatile in-situ mechanical test rig capable to simultaneously correlate the macroscopic/mesoscopic and sub-microstructure/sub-micrometer deformation and the changes in surface reactivity (oxide microcracking, oxide spallation, fast growing oxides, breakaway oxidation, etc.) at high temperature in various atmosphere conditions. Tracking changes in emissivity due local surface reactivity with full-field measurements (thermoreflectometry and/or CCD sensor) paired with kinematics field measurements (photomechanics means) bring an original dimension and justify the need for such experimental developments.
The main goal of this in-situ experimental characterization is to bring a novel understanding and a more physical prediction of the local and time-evolving mechanical behavior of graded materials at the microstructure scale related to environmental interactions. In a first approach, surface reactivity and surface effects due to mechanical loading will be separately investigated. To exacerbate surface reactivity and surface effects phenomena, size effect approaches will be adopted using specimens with various thicknesses ranging from micrometer to millimeter sizes, i.e. from high to low “surface/volume” ratio. For surface reactivity purpose, volume-limited material would be beneficial to sound and anticipate premature surface reactivity local degradations due to depletion of elements constitutive of stable and dense oxides (“reservoir effect”). Fast growing oxides subsequently form when the material reaches a critical threshold concentration of Cr and/or Al leading to the onset of breakaway oxidation. In parallel, the mechanical response of small-sized materials in the presence of a free-surface versus an oxidized surface will be examined due to changes in plasticity confinement. The thermo-mechano-chemical coupling will be then investigated in order to correlate the onset of reversible and irreversible strain localization at the microstructure scale (high resolution photomechanics means) due to an external loading with the surface reactivity localization and kinetic. As aforementioned, specific in-situ surface metrology will be developed in order to in-fine propose spatiotemporal evolution of emissivity as a signature of surface reactivity damages.

Project coordination

Damien Texier (Centre National de la Recherche Scientifique/Institut Clément Ader - UMR CNRS 5312)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CNRS/ICA-UMR CNRS 5312 Centre National de la Recherche Scientifique/Institut Clément Ader - UMR CNRS 5312

Help of the ANR 213,246 euros
Beginning and duration of the scientific project: - 42 Months

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