Under high temperature conditions, the hot-dip galvanized layer will undergo a series of changes, which will affect its performance as follows: Appearance changes: High temperature may cause the color of the hot-dip galvanized layer to change, turning yellow, gray, or even black. This is because high temperatures cause the zinc layer to oxidize, generating different zinc oxides, which in turn affect the appearance and color of the coating.
Changes in microstructure: The microstructure of the hot-dip galvanized layer changes at high temperatures. Zinc grains grow, and grain boundaries become blurred. This change in organizational structure alters the mechanical properties of the zinc layer, typically resulting in decreased hardness and increased toughness.
Changes in corrosion resistance: Generally speaking, within a certain temperature range, the corrosion rate of hot-dip galvanized layers will accelerate as the temperature increases. This is because high temperatures accelerate the chemical reaction between zinc and oxygen, moisture, and other corrosive media in the air, and may also damage the passivation film on the zinc layer surface, reducing its protective effect on the substrate. When the temperature exceeds a certain limit, the zinc layer may peel or flake off, further losing its protective properties.