In the relentless battle against corrosion, researchers from the Electric Power Research Institute of State Grid Hebei Northern Electric Power Co. and the China Electric Power Research Institute have developed a novel waterborne zinc-aluminum coating that could revolutionize the protection of steel structures in harsh environments, particularly in the energy sector. The study, led by SHU Zixi and colleagues, was recently published in *Cailiao Baohu*, which translates to *Materials Protection*.
Corrosion is a significant challenge for steel structures, especially in coastal and industrial environments. Traditional hot-dip galvanized coatings, while widely used, often suffer from early corrosion and poor resistance, leading to frequent and costly maintenance. The researchers aimed to explore the potential of environmentally friendly metal anti-corrosion coatings to address these issues.
The team developed two novel waterborne organic zinc-aluminum coatings. Coating 1 consisted of 45% zinc powder, 5% aluminum powder, and 50% film-forming resin. Coating 2 was formulated on the basis of Coating 1 with the addition of a waterborne inorganic-modified silicone resin topcoat. Both coatings were subjected to multiple high-temperature baking for curing.
The corrosion protection performance of the two coatings was compared with that of hot-dip galvanized coatings through salt spray testing, immersion testing, and electrochemical impedance spectroscopy (EIS). The results were revealing. “The traditional hot-dip galvanized coating began to corrode early in the test,” noted SHU Zixi, the lead author of the study. “Moreover, the generated corrosion products were loose and prone to spalling, resulting in poor corrosion resistance.”
Coating 2 exhibited acceptable corrosion resistance during the early to mid-period of the salt spray test. However, in the later stages, the poor compatibility between the inorganic-modified silicone resin and the zinc-aluminum powder hindered the electrochemical action of zinc, leading to blistering, rusting, and eventual failure.
In contrast, Coating 1 exhibited good adhesion and cohesion. During the early stage, the cathodic protection effect was mild but long-lasting, while the corrosion products of zinc and aluminum in the later stage provided effective shielding for the coating, resulting in significantly excellent corrosion resistance. “Coating 1, with its excellent adhesion, cohesion, and dual protection mechanism, exhibited significantly better corrosion resistance than both Coating 2 and hot-dip galvanized coatings,” SHU Zixi explained.
The implications for the energy sector are substantial. Steel structures, such as substation steel frame supports, are critical components in power infrastructure. The development of a coating that offers superior corrosion resistance can significantly reduce maintenance costs and enhance the longevity of these structures. This is particularly important in coastal environments, where the combination of salt spray and high humidity accelerates corrosion.
The study also revealed the negative impact of inorganic topcoats on the electrochemical behavior of zinc-aluminum coatings, offering new insights for optimizing coating systems. This research could pave the way for the development of more effective and environmentally friendly coatings for steel structures in various industries.
As the energy sector continues to expand and face the challenges of harsh environments, the need for durable and reliable corrosion protection becomes ever more critical. The work of SHU Zixi and colleagues represents a significant step forward in this field, offering a promising solution that could shape the future of coating technologies in the energy sector and beyond.