Acceleration of phosphating processes by electrochemical methods

Abstract
Electrochemical acceleration using potentiostatic control has revealed that in zinc-containing solutions two passive regions occur. The first region of -400 to -100m V (SCE) corresponds to the formation of hopeite; the second region of +400 to + 1400mV(SCE) corresponds to the formation of phosphophyllite. For manganese-containing solutions only one passive region occurs. The coatings produced were characterised by high coating weights (15–30g/m2) and low porosity values (<0.5%).