De l'impression 3d en céramique
Mesurer la déformation du sel, pour l'aménagement de réservoirs en cavités salines
Electromagnetic forming process for metallic pieces
Amélioration de la performance des éoliennes
Vers un stockage géologique du C02 avec impuretés
Quentin BLOCHET will defend his thesis which called
"Influence of substrate surface roughness on cold-sprayed coating-substrate bond strength in aluminum-based systems"
on november, 26 at 2:00 pm
at Ecole des Mines de Paris, 60 Bld Saint-Michel, Paris 6ème, in room L109
abstract : The cold spray process is based on high-speed spraying of a powder onto a substrate. The formation of a more or less dense coating depends on sprayed particle adhesion and coating build-up. The repair of metallic or composite aircraft / aerospace components is a recent application of cold spraying. The particle-substrate bond strength is due to various mechanisms, including mechanical anchoring. Substrate material hardness and surface topography governs the degree of mechanical anchoring. This thesis study is centered on the influence of these two contributions. Pure metallic and composite systems with different mechanical properties are selected. Particle deposition onto rough surfaces is investigated through the development of pure aluminium coating of harder aluminum alloy substrates.
Plastic deformation and build-up mechanisms are studied for Al-SiC coatings onto ductile substrate. All the coatings resulted from an optimization stage where process parameters and materials properties are considered (gas temperature, gas pressure, particle size). Particle impact conditions are also determined by particle speed experimental measurements (using a DPV 2000 system). Substrate temperatures are determined using thermocouple and particle temperatures are studied by numerical simulation. Mechanical anchoring of particles is investigated by cross-section observation of the coating-substrate interface. Hardness gradient is also quantified. An analysis of sand-blasted surfaces morphology is performed to correlate particle size and roughness parameters. A model of particle impact is established from a finite element analysis of interface plastic deformation as a function of surface topography. Lastly, dynamic adhesion testing using a laser shock (LASAT®) are undertaken to
study the potential role of interface roughness on the fracture thresholds in the light of a numerical analysis.