1.Why is zinc-aluminum-magnesium coating the first choice for improving corrosion resistance?
Core Advantages
Excellent corrosion resistance: The alloy coating containing 5-11% aluminum and 1-3% magnesium will rust for more than 1,500 hours in a low-temperature salt spray environment, which is 4 times that of ordinary galvanizing. The corrosion products are denser at low temperatures and have a solubility 70% lower than that of pure zinc corrosion products.
Self-repair of incisions: The magnesium element promotes the formation of a self-healing protective film at the incision, and the corrosion resistance of the cut edge is 6 times higher than that of pure zinc coating, which is suitable for refrigerated truck floors, cold storage shelves and other wear-prone scenes.
Low-temperature stability: The coating remains tough at - 30°C, and the thermal expansion and contraction coefficient matches the substrate to avoid cracking of the coating due to temperature differences.
2.What are the typical application scenarios of zinc-aluminum-magnesium coating?
Cold chain transport vehicles: zinc-aluminum-magnesium coating (ZAM150) combined with super-hydrophobic coating can extend the life of the refrigerated truck floor to 8-10 years in salt spray + vibration environment.
Large cold storage structure: The top plate adopts zinc-aluminum-magnesium coating + polyurethane insulation layer, and no red rust has appeared in 10 years of monitoring.
3.How to carry out composite treatment process in extreme environment?
Three-layer protection system
Base layer: zinc-aluminum-magnesium coating (ZAM150) provides sacrificial anode protection;
Middle layer: chromium-free passivation (silane) + silicon-based sealant to block the penetration of corrosive media;
Surface layer: low-temperature resistant polyurethane topcoat (flexible at -40℃), salt spray resistance >1000 hours.
4.How to choose the process without any requirements?
Lifespan requirement > 10 years: Prioritize zinc-aluminum-magnesium coating, such as cold storage structures and cold chain transport vehicles.
Limited budget and environmentally sensitive: silane passivation + sealing, suitable for food processing equipment and temporary facilities.
Quick solution to condensation water problem: super hydrophobic coating, suitable for refrigerated trucks and outdoor pipes.
Extreme low temperature + high corrosion: composite treatment process, such as aerospace tanks and deep-sea equipment.
5.What are the key points of construction and maintenance?
Zinc-aluminum-magnesium coating: Avoid exposing the substrate after cutting, and the cut needs to be coated with zinc-rich repair paint (zinc powder content ≥ 90%). Use insulating gaskets during installation to prevent galvanic corrosion caused by contact between dissimilar metals.
Silane passivation: After passivation, it needs to be sealed within 2 hours to avoid surface contamination. When constructing in winter, 5% ethylene glycol antifreeze can be added to ensure the fluidity of the solution.
Superhydrophobic coating: The surface of the substrate needs to be sandblasted to a roughness of Ra 6.3-12.5μm to enhance adhesion. When constructing at low temperatures, infrared heating equipment (80℃) is used to accelerate the curing of the coating.
Composite treatment: The interlayer adhesion needs to be tested by the cross-cut method (ISO 2409), and the grade is ≤1. Check the integrity of the topcoat regularly, and local damage needs to be polished and re-coated with the same type of coating.