Cesimiro Fabian

Electrodeposition process modeling using continuous and discrete scales

Chemical bath electro deposition process is used in many industrial applications to obtain a thin layer material on a target surface. Numerous metal, magnetic or semi-conductor materials, such as oxide, chalcogenure or alloys are obtained in electrochemical cells at laboratory scale. Some of these materials are interesting to be produced at industrial scale, for example for electronics, fuel cells or photovoltaic applications. In industrial electrochemical cells, dimension is larger and many parameters such as hydrodynamics or electro active specie transport are heterogeneous. There are many industrial electrochemical techniques in which the electrode moves with respect to the solution. These systems, like the rotating electrodes, are called hydrodynamic electrochemical processes. It is also interesting to notice that micronic structure, such as roughness, columnar structure or porosity of material deposit is local flow dependent. Then, it appears, that the material deposit composition and structural quality need integrated information from the micronic scale to the industrial scale, using, of course, the laboratory scale measurements. The aim of the present work is to model and to numerically simulate the hydrodynamics, electrochemical and chemical coupled phenomena, which are occurring during the chemical bath electro deposition process for laboratory and industrial configurations. Experimental measurements obtained at laboratory scale with zinc oxide thin layer deposit are used to identify transport or kinetic data input which are conserved during the scale-up. Flow and chemical species concentration field properties are calculated in the working electrode surface vicinity taking into account homogeneous and heterogeneous reactions. The numerical method used is the finite volume method. In addition, using a Monte Carlo method, micronic information is calculated such as the roughness and the porosity of the thin layer material obtained.

Hydrodynamic Modeling of Copper Electrodeposition at a Vertical Rotating Cylinder Electrode

The hydrodynamics of a rotating cylinder electrode were modeled to predict tertiary current distributions during electrodeposition of copper from acidic sulfate media, and to evaluate the effects of the resulting density gradients close to the electrode. Assuming no such density variations, then predictions of transport-limited current densities were in good agreement with Mizushina’s empirical law and with Leveque’s theoretical description, but not with measured values. Assuming a linear density variation with copper concentration, predictions of concentration profiles agreed to within 3 % of experimentally measured limiting current densities at the rotating cylinder electrode. For solution compositions relevant to copper electrowinning, a diffusion coefficient for cupric ions of 1.2×10 -9 m 2 /s at 45 o C, was inferred by solving the continuity, Navier-Stokes and mass balance equations with Fluent® computational fluid dynamics software.

Modeling The Electrodeposition Process:From The Macroscopic To The Mesoscopic,From Continuous Mathematics ToDiscrete Algorithms

The chemical bath electrodeposition process is used in many industrial applications to obtain a thin layer material on surfaces. Numerous semi-conductor or magnetic materials, such as oxide, chalcogenure or alloys, are obtained in electrochemical cells on a laboratory scale. Some of these materials are interesting enough to be produced on an industrial scale, for example for fuel cells or photovoltaic applications. In industrial electrochemical cells, dimensions are larger and many properties such as hydrodynamics or electroactive transport are heterogeneous. There are many industrial electrochemical techniques in which the electrode moves with respect to the solution. These systems, like the rotating electrodes, are called hydrodynamic electrochemical processes. It is also interesting to notice that the micronic structures, such as material deposit roughness or porosity, are local properties. The deposit velocity and structure need integrated information from the micronic scale to the industrial scale. The aim of the present work is to model and to numerically simulate the hydrodynamics and electrochemical coupled phenomenon which occur during the chemical bath electrodeposition process for classical electrochemical configurations. Experimental measurements obtained on a laboratory scale with copper deposits are used to identify a realistic modelling which can be assumed to be conserved during the scale-up. The numerical method used at the continuous scale is the finite volume method. In addition, using a Monte Carlo method, local micronic properties are calculated such as the roughness and the porosity of the thin layer material obtained.