Modelling of coating thickness distribution on the edges of a moving cathode during electrogalvanizing

Abstract

Electrogalvanizing is a widespread practice used to prevent steel corrosion. A mathematical model was developed to simulate the plating process and to predict the zinc coating thickness distribution at the cathode surface for different operating conditions. The model considers ternary current distribution, diffusion and electric field migration in the solution, and electrodeposition of zinc on a moving steel cathode. Experiments were carried out to validate the model using an experimental device which reproduces the fluid dynamic and electrochemical conditions of the edges of a steel strip in an industrial electroplating line, the rotating washer electrode. The model was solved using the finite element software COMSOLTM Multiphysics. The developed model accurately predicts the average thickness obtained by gravimetric tests. The shapes of predicted deposits are in good agreement with the experimental ones. Consequently, the model provides a valuable tool to simulate different working conditions at the laboratory and promises to be quite useful to optimize industrial electroplating systems.