Flow‐dependent zinc corrosion in boric acid‐containing electrolytes

In recent research concerning zinc dissolution studies in boric acid electrolytes, it was shown that moderate variations of the fluid temperatures or the boric acid concentration only cause small changes (<10%) in resulting initial zinc corrosion rates. A stronger dependency was found, however, on the fluid flow. Thus, a series of electrochemical measurements were carried out using a rotating disc electrode (zinc) in boric acid electrolytes for a better understanding of influencing parameters on the zinc corrosion rates. The main results of these electrochemical polarization experiments (e.g., Tafel plots) showed similar dependencies of the zinc corrosion rates as described in the aforementioned zinc dissolution experiments. The zinc corrosion process strongly depends on the mass transfer limitation of the dissolved oxygen to the zinc surface (cathodic process). Increased rotation speeds (higher flow rates) lead to extensively enhanced current densities (corrosion rates) and the extrapolation to infinite high rotation speeds (Levich extrapolation) was used to describe the corresponding corrosion process without transfer limitations.