Compared with the aluminum-zinc alloy, the galvanized layer has relatively active chemical properties, so the anti-corrosion ability is quite different. The test under the same outdoor conditions shows that the service life of the galvanized sheet is more than four times that of the galvanized sheet.
The aluminum-zinc alloy structure of the galvanized steel sheet is composed of 55% aluminum, 43.4% zinc and 1.6% silicon solidified at a high temperature of 600 ° C. The entire structure is composed of aluminum-iron-silicon-zinc, forming a dense quaternary crystal. Thus forming a layer of barrier that effectively prevents the penetration of corrosion factors.
Features of galvanized steel sheet:
Corrosion resistance:
The corrosion resistance of "55% Al-Zn Coil" comes from the barrier protection function of aluminum and the sacrificial protection function of zinc. When zinc acts as a sacrificial protection on the cut edges, scratches and coating scratches, aluminum forms an insoluble oxide layer and plays a protective role as a barrier. Aluminum-zinc alloy steel coils have been exposed to outdoor exposure tests for more than 20 years in various atmospheric environments, and it has been proved that the edge protection function of 55% aluminum-zinc-coated steel sheets is better than that of galvanized steel sheets and 5% aluminum-zinc-coated steel sheets. good.
Heat resistance:
The heat resistance of 55% aluminum-zinc alloy steel plate is better than that of galvanized steel plate, and it is similar to the high temperature oxidation resistance of aluminized steel plate. Aluminum-zinc alloy steel plate can be used in high temperature environment up to 315 degrees.
Reflectivity:
The 55% Al-Zn alloyed steel sheet is highly reflective, making it a heat resistant barrier; the galvanized steel sheet has almost twice the heat reflectivity of the galvanized steel sheet, so it acts as a roof and inlay when unpainted. The board can also achieve energy saving effect.
Paintability:
Due to the excellent adhesion between the zinc layer and the paint of the galvanized steel sheet, when it is used as a sign board for general purposes, it can be painted without pretreatment and weathering treatment; while the galvanized steel sheet needs weathering treatment and pretreatment. .
Application of galvanized steel sheet:
According to different thickness specifications, the main uses of galvanized steel plate are: PUF composite board, color steel tile, steel structure house, power distribution cabinet (thickness is 1.2-2mm); solar water heater (0.32mm); anti-theft door panel; home appliance back plate;
Hot dip galvanizing is generally used for steel strip or steel wire (stranded wire). The steel surface is covered with a zinc layer to block atmospheric erosion, so as to prevent the substrate from continuing to corrode and ensure the service life of the substrate. And zinc is more active than iron, and in the case of corrosion, the zinc layer can also be sacrificed to protect the steel matrix.
Aluminum-zinc plating has a stronger protective effect, and its corrosion resistance is better than that of galvanized products. The entire structure is composed of aluminum-iron-silicon-zinc, forming a dense quaternary crystal, which forms a barrier on the steel plate, thus effectively preventing the penetration of corrosion factors. The corrosion resistance comes from the barrier protection function of aluminum and the sacrificial protection function of zinc. When zinc acts as a sacrificial protection on the cut edges, scratches and coating scratches, aluminum forms an insoluble oxide layer and acts as a barrier protection.
