大跨度桥梁缆索用钢丝热浸镀层研究综述

综述了热浸镀Zn、Zn-Al和Zn-Al-Mg系合金镀层的性能特点和研究现状。在Zn-Al合金中添加Al元素可以减缓Zn的腐蚀氧化,同时可以在镀层表面形成致密的Al_2O_3薄膜起到屏蔽保护作用。在此基础上,采用Mg合金化,不仅可细化镀层组织,还可抑制疏松腐蚀产物的生成,进一步延长合金镀层的寿命。阐明了桥梁缆索用钢丝热浸镀工艺的特点和不足。采用中性盐雾试验评估了应力加载对桥梁缆索用热浸镀层组织和耐腐蚀性能的影响。应力加载会使镀层表面的腐蚀产物保护层破裂,加快腐蚀进程。同时指出了现有桥梁缆索用钢丝镀层评价标准尚存在一些争议,应结合现行的评价体系,重视讨论和探索新的更合适的评价标准。需要研究新一代(Zn-Al-Mg)合金镀层的制备技术和评价标准,推动具有高耐蚀性的多元合金镀层在桥梁缆索用钢丝上的推广应用。同时,桥梁缆索用钢丝热浸镀层的腐蚀性能应考虑应力加载下的腐蚀破坏和相关机理研究。

Research Progress of Hot-dip Coating for Bridge Cable Steel Wires

The performance characteristics and research status of hot-dip Zn, Zn-Al and Zn-Al-Mg alloy coatings were reviewed. The addition of Al in the Zn-Al alloy can retard the corrosion and oxidation of Zn, and at the same time, it can form a dense Al2O3 film on the surface of the coating to provide shielding protection. The addition of Mg element not only refines the coating structure, but also suppresses the formation of loose corrosion products and prolongs the life of the alloy coating. The effect of stress loading on the microstructure and corrosion resistance of hot dip coatings for bridge cables was evaluated by neutral salt spray test. The corrosion protection layer on the surface of the coatings can be destroyed by stress loading and then lead to accelerate the corrosion process. There are still many disputes about the existing coating evaluation standards for bridge cable steel wires. It should be combined with the current evaluation system to emphasize and discuss new and more suitable evaluation criteria. It is necessary to study the preparation technology and evaluation criteria of a new generation of (Zn-Al-Mg) alloy coatings, and promote the popularization and application of multi-alloy coatings with high corrosion resistance on bridge cable steel wires. At the same time, the corrosion damage of hot-dip coating for bridge cable steel wires under stress loading and related mechanisms should be considered.