Numerical model for predicting the efficiency behaviour during pulsed electrochemical machining of steel in NaNO3

A new two-dimensional model is presented that allows describing the high speed electrochemical machining of steel in NaNO3 solutions. Unlike existing models, local ion concentrations are calculated and used to evaluate local diffusion coefficients and electrolyte conductivity. Secondly, the presence of a super-saturated, honey-like layer on the anode surface is accounted for by introducing a water depletion factor. This factor describes the suppression of the oxygen evolution as the vast increase in ion concentrations reduces the amount of free water molecules at the anode. It is demonstrated that this approach enables to reproduce experimental average efficiency curves over a broad range of electrolyte concentrations with just a limited set of adjustable parameters.