Q:What is the definition of aluminum galvanizing?
A:Aluminum galvanized sheet adopts hot-dip coating process, immersing cold-rolled or hot-rolled steel sheet into molten aluminum-zinc alloy liquid at a temperature of about 600℃, so that a dense alloy coating is formed on the surface of the steel sheet. The coating is mainly composed of aluminum (Al) and zinc (Zn), with a typical ratio of 55% aluminum, 43.4% zinc, and 1.6% silicon (referred to as 55% aluminum-zinc coating). Other processes may contain a small amount of magnesium, iron and other elements.
Q:What is the process flow of aluminum galvanized sheet?
A:Substrate pretreatment (degreasing, pickling) → hot-dip aluminum-zinc alloy liquid (temperature control ±5℃) → air knife blowing coating thickness → cooling → surface treatment (passivation, anti-fingerprint coating) → finished product.
Q:What are the core advantages of aluminum galvanizing?
A:Corrosion resistance: The corrosion resistance of aluminum-zinc coating is 2-6 times that of ordinary galvanized sheet (pure zinc coating), especially in industrial atmosphere (containing sulfide) and marine environment (high salt), and the service life can reach 20-30 years.
Heat resistance: It can withstand long-term high temperature of 300℃ (the zinc layer of galvanized sheet begins to melt above 200℃), suitable for high temperature scenes such as chimneys and ovens.
Processing performance: The coating has good ductility and can adapt to stamping, bending, and roll forming. The surface is smooth and delicate, suitable for painting (such as color spraying of home appliance shells).
Q:What are the application scenarios of aluminum galvanizing?
A:Construction: roofs, exterior wall panels (excellent weather resistance, suitable for coastal or industrially polluted areas); ventilation ducts, cable trays (high temperature resistance, corrosion resistance).
Home appliance manufacturing: ovens, water heater shells (resistant to high temperature environments), air conditioner outdoor units, refrigerator back panels (resistant to salt spray corrosion).
Automotive industry: exhaust pipe guards, chassis components (resistant to high temperature oxidation and road salt corrosion).
Agriculture and industry: granaries, chemical plant buildings (resistant to corrosion and chemical gas erosion).
Q:What is the key difference between aluminum galvanizing and ordinary galvanizing?
A:1. Corrosion mechanism:
Ordinary galvanizing: zinc protects steel through sacrificial anodes, and the zinc layer is gradually consumed.
Aluminum galvanizing: aluminum forms a dense oxide film (Al₂O₃) to block the corrosive medium, and zinc provides local cathodic protection, and the double protection is more durable.
2. Service life: Under the same thickness, the service life of aluminum galvanized sheet in a typical environment can reach 20~30 years, far exceeding the 10~15 years of ordinary galvanized sheet.
3. Welding and processing: The aluminum galvanized layer has a high hardness, special lubricants are required for stamping, and welding parameters need to be adjusted (such as gas shielded welding).