CHARACTERIZATION AND ADHESION STRENGTH STUDY OF ZN COATINGS ELECTRODEPOSITED ON STEEL SUBSTRATES

High-quality Zn coatings are electrodeposited, on low-speed rolled ste el substrates, at a high current density of 50 A dm(-2). A quantitativ e determination of the adhesion strength of these coatings is carried out with the four-point bending test. The substrate surface roughness is controlled by mechanical polishing before deposition. Mechanical in terlocking, created by the polishing process, is the main phenomenon d etermining the adhesion mechanism of the Zn coatings on the steel subs trates. An optimal value of about 0.3 mu m was observed for the substr ate surface roughness. The results are discussed in the proposed adhes ion mechanisms. (C) 1998 Elsevier Science S.A.