Zn-Mn alloy electrodeposition on steel

Electrodeposition of Zn-Mn (0 divided by 50 w/o) onto carbon steel sheet and wire is discussed in the present paper. An original bath is proposed and effects of stabilisers are studied. Baths and deposits are studied from the electrochemical and structural points of view. Electrochemical investigations include galvanostatic and potentiodynamic studies carried out in laboratory cells under natural and forced (rotating disk electrode) convection and a wire-plating pilot plant. Structural and compositional investigations include X-ray diffraction analyses, scanning electron imaging and energy dispersive analyses on steel sheet and wire. Electrochemical data can be correlated with alloy composition (limiting currents and how they are affected by mass transport conditions), morphological results (lamellar low-Mn vs. globular high-Mn) and crystallographic (metastable epsilon monophasic deposits in the high-Mn range, polyphasic low-Mn coatings) structure, the variables which have a bearing on functional properties of the coatings.