Verification of Reinforced Surface Loose Layer of Zinc–Aluminum–Magnesium Steel Plate

Abstract

The corrosion resistance of zinc–aluminum–magnesium steel plates (Zn–Al–Mg steel plates) is significantly higher than that of galvanized steel plates. However, the unsatisfactory bonding performance of Zn–Al–Mg steel plates significantly limits their widespread application. In this study, X-ray photoelectron spectroscopy is employed to detect changes in the surface oxygen content of Zn–Al–Mg steel plates after different temperature treatments to confirm the existence of surface loose layers. In particular, changes in the surface oxygen content of the Zn–Al–Mg steel plates after the oxide layer is removed are investigated under saturated H2O vapor and O2 environmental conditions, and the cause of the formation of loose surface layers is determined. The uneven distribution of elements on the surface of the Zn–Al–Mg steel plates is investigated with scanning electron microscopy and energy dispersive spectroscopy. Nuclear magnetic resonance is employed to determine the size of the network spatial structure formed by silane coupling agents under different hydrolysis conditions and to further investigate the bonding performance of hydrolysate-modified Zn–Al–Mg steel plates. Several typical automotive adhesives are utilized to compare and examine the changes in the tensile strength of the Zn–Al–Mg steel plate bonding before and after modification with the silane coupling agent and analyze the structural damage of the adhesive at the bonding interface. The results confirm that the silane coupling agent strengthens the loose layer on the surface of the Zn–Al–Mg steel plate.

Contributions to a More Realistic Characterization of Corrosion Processes on Cut Edges of Coated Metals Using Scanning Microelectrochemical Techniques, Illustrated by the Case of ZnAlMg-Galvanized Steel with Different Coating Densities

“…The as-received samples presented a heterogeneous appearance at the millimetre range, as confirmed by optical profilometry. Figure 1 shows illustrative images of the samples, which exhibit flake-like morphologies similar to features reported in the literature for ternary galvanic coatings [48][49][50]. The black spots seen in the images result from the denoise algorithm used for plotting and do not correspond to actual features appearing at the surface.…”

“…The black rust seen in label 3 is a precursor to the tarnishing process. Zinc particles between 7 and 10 µm are randomly dispersed on the surface (label 4), while zinc dendrites (label 5) and eutectic phases (label 6) are also observed [49,50]. The elemental distribution of oxygen on the surface accompanies the presence of Al and Mg as more reactive elements, thus leaving areas of metallic zinc readily exposed to the environment.…”