Characterization and adhesion strength study of Zn coatings electrodeposited on steel substrates

Abstract High-quality Zn coatings are electrodeposited, on low-speed rolled steel substrates, at a high current density of 50 A dm −2 . A quantitative 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 interlocking, created by the polishing process, is the main phenomenon determining the adhesion mechanism of the Zn coatings on the steel substrates. An optimal value of about 0.3 μm was observed for the substrate surface roughness. The results are discussed in the proposed adhesion mechanisms.