Abstract:

To improve the corrosion resistance of traditional pure Zn coatings, we used 30 mm diameter Q195 welded pipes as the substrate and prepared a series of hot-dip galvanized alloy coatings by adding trace amounts of alloy elements such as Al, Ni, and Re to the Zn bath. First, the main factors affecting corrosion resistance were identified through a four-factor and three-level orthogonal experiment. Then, the experiment was further improved for the primary factors, and single-factor experiments were conducted to obtain the optimal parameter combination. Finally, the microstructure characteristics and corrosion resistance of the coating were studied and analyzed using methods such as high and low temperature humidity test, neutral salt spray test, metallographic analysis, and scanning electron microscopy. Results indicate that the introduction of alloying elements suppresses the growth of ζ layer, which makes the coating structure compact, and improves the corrosion resistance of the coating. The coating prepared in this study could remain rustless throughout a 72 h salt spray test and a 120 h humidity test. The process for preparing the alloy coating is same as the existing production process for traditional Zn coatings.

Key words: hot-dip, galvanizing, alloy coating, aandelin effect