What is PosMAC (POSCO Magnesium Aluminium Alloy Coating Product) ?
- - 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.
Corrosion resistance of PosMAC
- - 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.
Higher corrosion resistance
- - 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
|The coating weight
on both side
Weathering test on cross-section part (Korea conformity laboratories)
- - 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).
|After 6 months||After 1 years||After 2 years|
Product charcteristics comparison
|Hardness(Hv) of coating layer||110~130||60~80||80~100|