Effect of Nickel Precoating on Wettability of Twinning-Induced Plasticity Steels by Liquid Zn-0.23 Wt Pct Al

The effect of the nickel precoating on the wettability and the corresponding coating property of twinning-induced plasticity steel (17 wt pct Mn-1.2 wt pct Al-0.1 wt pct Si-0.5 wt pct C) by liquid Zn-0.23 wt pct Al were investigated. Annealing and Zn coating experiments were carried out in a galvanization simulator, and Zn wetting experiments were performed with a dispensed drop test machine. The experimental results showed that nickel precoating improved the Zn wetting property. SEM, XPS, and TEM analyses showed that nickel precoating decreased the thickness of surface oxides and thus improved the Zn coating property. It was speculated that oxygen adsorption on the nickel surface might be suppressed. In addition, Al 2 O 3 was found just below the nickel precoating layer, and this indicated that the oxygen potential in the subsurface region was considerably decreased.