For galvanized steel ducts, understanding the "galvanizing" process is the logical starting point for analyzing all its characteristics. This process is not a simple coating, but a precise metallurgical combination. Typically, clean low-carbon steel sheets are immersed in molten zinc, and through a hot-dip galvanizing process, a zinc-iron alloy layer and a pure zinc layer are formed on the steel surface. This composite layer structure is the cornerstone of all subsequent properties of the galvanized steel sheet.
The mechanism of the zinc layer can be analyzed from two levels. First, there is the physical barrier effect: the dense zinc layer completely covers the steel substrate, isolating the steel from corrosive media such as moisture and oxygen in the air, thus slowing down the rusting process. Second, there is a more unique electrochemical protective effect. In the metal activity sequence, zinc is more reactive than iron. When the coating is damaged and the steel substrate is exposed, zinc acts as the anode, preferentially undergoing oxidation (corrosion), while iron acts as the cathode and is protected. This "self-sacrificing" protection means that even if the coating has minor scratches, the surrounding zinc can still protect the steel from rusting, a characteristic that significantly improves the material's durability.
