Mechanistic understanding of Zn-based coating on high-strength pearlitic steel wire for bridge cable

Abstract

Corrosion usually leads to premature failure of bridge cable steel wire. In order to further improve the corrosion resistance of hot-dipped galvanized steel wire for bridge cables, a new type of Zn-10Al-RE alloy coating was designed. The Al content of the traditional coating was increased, and RE was added to improve the coating performance. Combined with electrochemical experiments and first-principles calculations, the enhancement effect of RE element on the performance of the coating was clarified. The Zn-10Al-0.1RE coating exhibited the most uniform microstructure, characterized by a refined eutectic phase structure, which facilitated the formation of dense and protective corrosion products. Electrochemical tests and neutral salt spray experiments demonstrated superior corrosion resistance, with the 0.1 % RE-doped coating showing the lowest corrosion rate (16 mg m⁻² h⁻¹ after 1200 h). First-principles calculations revealed that RE doping increases surface stability by reducing surface energy and enhancing ion adsorption, thereby promoting the formation of protective Zn₅(OH)₈Cl₂ and ZnAl-LDHs−CO₃ layers. The findings highlight the synergistic effects of Al and RE in improving corrosion resistance, providing insights for designing high-performance Zn-based coatings for bridge cable.