Description :
Full description : https://cloud.minesparis.psl.eu/ind...

Context :
Dip-coating processes consist in covering an object with a thin layer of liquid, using sequences of immersion in a bath and removal at well-chosen speeds and trajectories. Layer thickness control depends a lot on previous steps, as well as fluid rheology ; end-use target properties are in turn affected by those parameters. Lost-foam casting, a foundry method used in last generation engines made at Stellantis, includes such coating technique : a polystyrene model of the final object is dipped and covered by a suspension of particles. Once it has dried, gas coming from polystyrene decomposition can escape easily while liquid metal poured on top of it stays inside. Suspensions rheological behavior is complex and plays a lot in final object surfaces quality.

Goals and planning :
This PhD thesis main goal is to understand, predict and tune final deposited thicknesses on arbitrarily complex geometries, playing on bath rheology and object removal trajectories and speeds.
First, an experimental and theoretical approach will be used to apprehend all unitary mechanisms and instabilities at play when an object is covered by yield stress fluids (the bath), and when it is simply immersed and removed from it by translation movement, with model geometries (spheres, plaques…). Experimental device will consist in a laboratory scale robot arm, able to perform complex bath removal moves. Layer thicknesses measurements will be performed thanks to local laser distance sensors, for optimal precision,
as well as on-board cameras for global kinetics, dripping and flow characterizations.
Layers flow modelling will be then implemented in a numerical simulation code. Our approach will as a result be extended to more complex geometries and trajectories, ideally integrating real-time computing and feedback loops, to, finally, be applied to real industrial processes.
This project will take place in the Center for Material Forming (Cemef) of Ecole des Mines de Paris – PSL University, located on Pierre Laffitte Campus in Sophia Antipolis (France). Many stays and interactions are planned as well with Stellantis, the project industrial partner. The candidate will be part of Cemef Computing and Fluids research team.

Reference :

Date de démarrage : 03 octobre 2024

Durée : 3 years

Contacter :
Mines Paris, CEMEF
Rudy Valette, Romain Castellani
1, rue Claude Daunesse 06904 Sophia Antipolis cedex France
email : romain.castellani@minesparis.psl.eu