1.What are the differences in service life in different environmental applications?
Mild indoor environment (dry, pollution-free): Under such ideal conditions, the zinc coating itself can provide very long protection, and theoretically it may not rust for more than 15 years or even decades. There is usually a layer of anti-fingerprint oil or passivation film on the surface to further protect the zinc layer.
Ordinary indoor environment (with slight humidity changes and no corrosive gases): This is the most common application scenario (such as computer cases, inside the housing of household appliances). If the coating is not damaged, it can usually maintain a good condition for 10-15 years.
High humidity indoor/mild outdoor sheltered environment: Such as bathrooms, kitchens (avoid direct splashing), sheltered balconies, etc. The corrosion rate will accelerate and the life span may be around 5-10 years.
Industrial environment/coastal environment: The air contains corrosive substances such as sulfur dioxide and salt spray. Under such harsh conditions, the zinc layer corrodes very quickly. Even with a coating, white rust (corrosion product of zinc) may appear within 1-3 years, and if the protective layer is damaged, the substrate will rust faster.
Directly exposed outdoor environment (wind, sun and rain): SECC is not designed for long-term direct exposure to the outdoors. Rain, ultraviolet rays, and pollutants will accelerate the consumption of the zinc layer. The lifespan is usually short, and maintenance or replacement may be required after only a few years, and rust will soon appear.
2.What is the difference in service life when the thickness of the galvanized layer is different?
The thicker the zinc coating, the greater the "sacrificial amount" of zinc, and the longer it protects the substrate. The thickness of the SECC zinc coating (usually expressed in g/m², such as 20/20, 30/30, etc.) is an important parameter when selecting. Thicker coatings (such as 40/40 or above) are naturally more durable than thin coatings (such as 20/20)
3.What is the difference in service life between surface treated and untreated surfaces?
Passivation treatment: SECC is usually chromated when it leaves the factory (chromium-free passivation is also popular), forming a protective film to delay the oxidation of the zinc layer (white rust), which is very important for improving short-term corrosion resistance.
Anti-fingerprint oil: Many SECCs are also coated with an extremely thin layer of anti-fingerprint oil (AFO), which is both anti-fouling and provides a certain amount of additional anti-rust protection.
Subsequent coating (spraying): This is the most effective way to greatly improve the corrosion resistance of SECC. Spraying (such as powder spraying and painting) on the SECC substrate isolates the zinc layer from the environment. Its life mainly depends on the quality and durability of the spray coating, which can easily reach more than 10 years or even longer, even in relatively harsh environments.
4.What should we pay attention to when designing and processing products?
The design should avoid water accumulation and facilitate drainage.
Processing processes such as stamping, bending, and welding may damage the galvanized layer and passivation film (especially at cuts, edges, and welds), which will become the starting point of corrosion.
Scratches and collisions during transportation, installation, and use will also damage the protective layer, leading to localized preferential corrosion.
5.What is the approximate service life of SECC?
In well-controlled ordinary indoor environments (such as inside electronic and electrical housings), SECC itself (without spraying) can usually provide 10-15 years of effective anti-rust protection.
In harsher indoor environments (such as high humidity) or mildly shielded outdoor environments, the lifespan may be shortened to 5-10 years.
In industrial areas, coastal areas or directly exposed outdoors, SECC itself has insufficient corrosion resistance and may show obvious corrosion in 1-3 years, making it unsuitable for long-term direct exposure.
When used as a substrate for spraying (powder spraying, painting), its corrosion resistance mainly depends on the performance of the coating, which can achieve excellent performance of more than 10 years or even decades. This is the most extensive and reliable application of SECC.