Investigation of agglomerated and porous ceramic powders suitable for cold spray

It is now well established that metallic materials can be deposited by cold spray. For ceramic materials, such solid-state deposition process is still questionable but it was shown that thick and adhesive coatings could be obtained with specific ceramic powders. In the CERASOL project (ANR-19-CE08-0009), the nature and the architecture of porous ceramic powders involving agglomerated submicronic grains by cold spray is assessed. To that purpose, various agglomerated oxide ceramics (alumina, zirconia and yttria) have been investigated involving powders with different calcination temperatures and particle sizes. These powders were analyzed in order to study their architecture (particle size, porosity, density, crystallite sizes…). Cold spray experiments with high and low pressure cold spray systems were carried out to study a various range of impact velocities measured by DPV-2000. The microstructures of the resulting coatings have been investigated mainly by SEM and XRD in order to discuss the deposition behaviors that promote fragmentation and consolidation of the nanostructured agglomerated particles. The adhesion of the ceramic layers has been also investigated by LASAT (Laser Shock Adhesion Test). The role of the gas stream that affects the kinetic of the particles and also the trajectory through the creation of a bow-shock is also discussed.