- - PosMAC is a ternary alloy coated steel(Zn-94.5%, Mg-3%, Al-2.5%) with high corrosion resistance developed by POSCO’s own technology.
- - PosMAC is a corrosion resistant product that is 5 to10 times stronger resistant than that of a normal hot-dip galvanized steel sheet(GI, GI(H)) with the same coating weight. PosMAC has an excellent cross-section corrosion resistance; nomal thick plating products can be replaced with this product.
- - The same processing, assembly and painting process can be applied to PosMACas one would apply to GI.
- - The magnesium(Mg) in PosMAC’s coating layer will accelerate formation of a dense corrosion product called “Simonkolleite” which is extremely stable. When simonkolleite is formed on the surface of the coating layer in a film-like-form, it plays a role as acorrosion inhibitor for the base metal.
- - In addition, the upper coating layer can be dissolved to cover the cross-section and accelerate the growth of a stable corrosion product. However red-rust can be found in the already exposed steel plate, but for tunately, the film of the corrosion products covers the cross-section and serves to prevent corrosion.
- - PosMAC shows 5 to 10 times the corrosion resistance compared to galvanized steel sheet on flat surfaces.
- - In addition, PosMAC shows equal or greater corrosion resistance than galvalume on flat surfaces
| CCT | GI(H) | Galvanume | PosMAC | |||||
|---|---|---|---|---|---|---|---|---|
| The coating weight on both side |
120g/㎡ | 200g/㎡ | 300g/㎡ | 600g/㎡ | 100g/㎡ | 140g/㎡ | 200g/㎡ | 275g/㎡ |
| 10 cycle (80Hr) |
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| 70 cycle (560Hr) |
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| 120 cycle (960Hr) |
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- - PosMAC also gets red-rust in cross-section parts when initially exposed outdoors. However as the time goes by, the corrosion (red-rust) area of PosMAC tends to decrease through the formation of its distinctive oxide-based material(simonkolleite).
| Sample | Thickness | Coating weight (g/㎡) |
Cross-section image | ||
|---|---|---|---|---|---|
| After 6 months | After 1 years | After 2 years | |||
| PosMAC | 1.2 | 130 | |||
| 1.6 | 120 | ||||
| 2.0 | 300 | ||||
| Galvanume | 1.6 | 120 | |||
| GI(H) | 1.6 | 180 | |||
| Quality items | PosMAC | GI(H) | Galvanume | |
|---|---|---|---|---|
| Hardness(Hv) of coating layer | 110~130 | 60~80 | 80~100 | |
| Friction Characteristics | ◎ | X | △ | |
| Corrosion resistance |
Flat sheet | ◎ | △ | ◎ |
| Bending | ◎ | △ | △ | |
| Cup | ◎ | △ | ◎ | |
| Cross-section | ◎ | △ | X | |
| Chemical resistance | ◎ | △ | △ | |
| Weldability | ◎ | ◎ | ◎ | |