2005 Volume 54 Issue 11 Pages 526-531
The effect of rotation rate upon potential and etch rate of steel is examined utilizing a rotating steel disk electrode. Being based upon these experiments, etching mechanism is discussed.
The principal ingredient of etchants is FeCl3. The concentrations of FeCl3, FeCl2 and free HCl are 49 to 54 mass%, 1.9±0.1 mass% and 0.09±0.02mol/kg (molality), respectively. The temperature of the etchants is maintained at 70°C and the rotation rate of the steel disk is set at 400-4900rpm. The etch rate is obtained from the weight loss.
The etch rate and the square root of rotation rate are in proportionate relations at any concentrations of FeCl3. The mechanism that anodic and cathodic reactions are controlled by mass transfer process is proposed.