13. What is zinc nickel alloy? What role does it play in hot-dip galvanizing?

Zinc-nickel alloy is an alloy material formed by mixing zinc and nickel in specific proportions. The application of zinc-nickel alloy offers the following benefits for hot-dip galvanizing: (1) Enhanced corrosion resistance and adhesion. The excellent corrosion resistance of zinc-nickel alloy significantly improves the protective properties of the coating. Both zinc and nickel are inherently corrosion-resistant metals, and their combined use in alloy form further enhances this characteristic. The zinc-nickel alloy coating effectively prevents substrate erosion from external environments, thereby extending product lifespan. Additionally, the coating demonstrates strong adhesion, firmly adhering to the substrate surface without peeling off.
(2) Suppressing Excessive Coating Thickness and Poor Adhesion During Hot-Dip Galvanizing. In galvanizing processes, particularly for materials like silicon-containing active steels, conventional zinc coating often results in excessive thickness and poor adhesion. The addition of zinc-nickel alloy effectively addresses these issues. Incorporating a small amount of nickel into the zinc bath inhibits the rapid growth of the Z phase in the Fe-Zn alloy layer, resulting in a thinner coating that enhances adhesion and surface quality. For specific materials such as silicon-stabilized steels, the zinc-nickel alloy also eliminates coating thickness overgrowth caused by the Saint-Deslaurier effect.
(3) Uniformly Enhance Coating Performance: The zinc-nickel alloy coating uniformly improves corrosion resistance, impact strength, and surface rigidity, thereby extending the service life of workpieces. Under harsh conditions such as high temperatures and high pressures, the coating maintains its superior performance, ensuring product stability and reliability.
(4) Reducing Production Costs and Process Complexity The use of zinc-nickel alloy can significantly lower production costs. Although zinc-nickel alloy may be slightly more expensive than pure zinc, its superior performance and extended service life effectively offset this cost difference. Moreover, the addition of zinc-nickel alloy does not substantially increase the complexity of production processes or equipment requirements, making it easy to implement and apply in practical manufacturing.
(5) Enhancing coating uniformity and aesthetics. Zinc-nickel alloy coatings deliver a uniform appearance and excellent gloss, significantly improving product visual appeal. In applications demanding premium surface quality-such as automotive exterior components and architectural hardware-these coatings meet elevated aesthetic standards.