Physics-Based and Data Driven Modeling of Electrophoretic Coatings: Hybrid and Multiphysics Strategy
Authors: Fedi Baptiste , Schoenleber Jonathan , Boucher Aurélien 
Published: December 2024

Electrophoretic coatings are used in several applications where surface treatment is intended to provide corrosion protection. These coatings are widely used in the automotive, aerospace, or many other sectors. These kind of coatings are electrochemically applied and have good levelling, penetration, adhesion, and corrosion resistance properties. A wide variety of materials can be deposited by this technique and among these coatings, this presentation will focus on ceramic deposits. In this case, electrophoretic deposition is carried out using a suspension containing ceramic particles and the deposition takes place on a conductive substrate through the application of an electric field. The control of process parameters and post-processing parameters (heat treatment or sintering) necessary to consolidate the raw coatings obtained can be difficult to define.

In order to improve process management and understanding of electrophoretic deposition, we will explore several strategies and modelling theories implemented in the field of electrophoretic coating through a comprehensive analysis in order to optimize the coating process, improve quality and increase efficiency on complex geometry parts. Several theoretical approaches and models have been used to better understand electrochemical interactions and forces involved in electrophoresis to identify parameters related to electrophoretic mobility. The multiple parameters involved in electrophoretic coatings make the modelling of this process complex and the models developed are neither universal nor applicable to all chemistries which requires a specific development for each electrolyte and suspension.

In a second part, we discuss limits of theoretical models and describes a strategy to develop a new modelling approach. This approach combines a physics-based model of current distribution and a data-driven optimization applied to electrophoretic coating. This methodology allows to model the thickness distribution on a part with complex geometry on an industrial scale, with the ability to adapt to a variation in the chemistry of the suspension used. This hybrid methodology allow to reduce experimental and fundamental characterizations, and can be easily applied to a new chemistry to estimate and well describe the throwing power at a macroscale.

Furthermore, in some cases, physics-based modeling with secondary distribution can exhibit accuracy defects when the local concentration of particles drops, due to their consumption and low mass transport phenomena.

In order to better describe the process behavior in this specific case, we develop a multiphysics model of tertiary current distribution than can account for the local distribution of particles, particularly near the part. This modeling approach allows to better anticipate thickness distribution in areas with low fluid mixing and agitation. The local efficiency is linked to the local current and particle concentration, as describe by a two phase flow model.

The models developed are intended to help accurately predict and control the distribution of coating thickness and also local particle concentration to predict critical depletion zones.

In conclusion, this conference explore different modeling strategies of electrophoretic coatings, by focusing on the optimization of process parameters and the consideration of the different mechanisms governing deposition with the objective of improving coating distribution on complex part.