CE08 - Matériaux métalliques et inorganiques et procédés associés

Agglomerated powders for thick ceramic coatings by solid-state dynamic spraying – CERASOL

ANR CERASOL

The aim of the CERASOL project (ANR-19-CE08-0009) is to develop ceramic powders adapted to cold gas dynamic spraying known as “cold spray” process.

Goals of the project

To achieve this, the main objectives are:<br />(1) to improve the understanding and control of macro and micro deformation, adhesion and layer construction mechanisms from specific agglomerated powders deposited on a rough metallic substrate,<br />(2) to establish the influence of the nature of the material and the varied architectures of the powders on these mechanisms and on the particular characteristics of the resulting microstructures and interfaces,<br />(3) to optimize the powders to favor the deposition process in the solid state also involving thermosenstive additives or dopants,<br />(4) to generalize the results for each range of brittle material and rationalize the choice of process parameters that could lead to thick and adherent coatings with interesting properties.

The developments in CERASOL are based on the mastery of the «design« of agglomerated ceramic powders with controlled porosity for which the degree of agglomeration as well as the size of the powders are controlled.
design of agglomerated ceramic powders with controlled porosity for which the degree of agglomeration as well as the size of the grains and crystallites can be modified and studied on various ceramics
and crystallite size can be modified and studied on ceramics of various hardnesses and toughnesses representative of various applications various limited applications during sintering or fusion

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- 5 grades with 2 to 3 batches per grade with specific surface areas varying from 8 to 85 m²/g and crystallite sizes from 25 to 150nm with acicular or more or less elongated spherical shapes. The flowability is also assessed under spray conditions and is not in favour of the finest powders studied (D50=18µm typically) and the most sensitive to humidity (need for steaming to limit clogging of the dispenser).
- The reference powders are in the form of nanostructured granules of high compactness.
- Velocity maps measured at different spraying distances for HP and BP cold spray shots with the Hi-Watch (IrCer) or DPV2000 (CdM) velocity diagnostic equipment allowed to establish the supersonic velocity zone of ceramic particles.
- Only the HP equipment allows to obtain velocities >500m/s for firing distances higher than 100mm
- It was shown that the opening of the particle jet could depend significantly on the nature of the powder.
- All the oxide ceramic powders based on Al, Zr or Y were sprayed by HP and/or BP cold spray with «line« experiments for the realization of beads or isolated particles or surfacing (monolayer). With regard to the experiments, efforts were concentrated on zirconia (2 grades) and yttrin (1 grade) with the achievement of relatively thick layers.
- The case of alumina seems to be much more difficult to deal with, despite tests for different gas parameters and spraying distance. The result is a powdery film that does not reflect a process of material addition but only intense fragmentation.


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- The optimization of the powders is then posed in terms of porosity of the granules and also the addition of binder (PVA) to improve the projectability of the powders chosen in CERASOL.

[1]G. Celeste, V. Guipont, D. Missoum-Benziane, Investigation of Agglomerated and Porous Ceramic Powders Suitable for Cold Spray, in: F. Azarmi, X. Chen, J. Cizek, C. Cojocaru, B. Jodoin, H. Koivuluoto, Y.C. Lau, R. Fernandez, O. Ozdemir, H. Salimi Jazi, F. Toma (Eds.), Virtual, 2021: pp. 139–146. doi.org/10.31399/asm.cp.itsc2021p0139.
[2] D. Chatelain & al., Preparation of hydroxyapatite ceramic powders adapted to cold spray process, International Thermal Spray Conference (ITSC), virtual event, 24 – 28 May 2021,(oral)
3] D. Chatelain & al., Mise au point de poudres céramiques adaptées au cold spray (Oral) journées annuelles du Groupe Français de la Céramique Caen 23-25/03 2021 (oral)

The aim of the CERASOL program is to develop ceramic agglomerated powders adapted to the cold gas dynamic spraying process
"cold spray" to preserve the nature and composition of the sprayed materials. The cold spray can be used in the coating and surface
modification technologies but also is entering the additive manufacturing route. Its application to obtain dense for dense ceramic
deposits in the sold-state requires an better understanding of deformation and adhesion mechanisms during impact and layer
construction. The developments in CERASOL are based on the "design" of agglomerated ceramic powders with controlled porosity
for which the degree of agglomeration as well as the size of grains and crystallites can be varied and studied on ceramics of varying
hardness and toughness with potential use for various applications.

Project coordinator

Monsieur Vincent Guipont (ASSOCIATION POUR LA RECHERCHE ET LE DEVELOPPEMENT DES METHODES ET PROCESSUS INDUSTRIELS Centre des Matériaux de Mines ParisTech)

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

ARMINES CdM ASSOCIATION POUR LA RECHERCHE ET LE DEVELOPPEMENT DES METHODES ET PROCESSUS INDUSTRIELS Centre des Matériaux de Mines ParisTech
IRCER IRCER
MEDICOAT France MEDICOAT FRANCE
NANOE

Help of the ANR 605,621 euros
Beginning and duration of the scientific project: October 2019 - 42 Months

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