Numerical modelling of the growth of electrodeposited chromium on corner-shaped cathodes

In this paper, we propose the numerical simulation of the internal Cr-plating process of bored gunbarrels, displaying corner-shaped features. The growth of the Cr layer over a machined step is simulated by modelling the current density distribution under mixed activation and mass-transport control and correlating the local instantaneous current density to the growth rate. The problem with non-linear and time-dependent boundary conditions is solved by the FDM method in an iterative scheme. Experimental kinetic data were used to obtain an analytical form of the boundary conditions (relating local overvoltage to local current density); original routines were devised in order to achieve efficient convergence with realistic cathodic kinetics. Experimental parameters from an industrial production plant were used to model the hydrodynamic effects on the growth of the coating. Predictions of Cr-coating growth profiles were compared with experiments.