Galvanized layers and galvalume layers have their own advantages and disadvantages. 55% Al-Zn-Si plated layer not only sum up the advantages of both, but also overcome their shortcomings. This is because of its special structure of the cladding material. Hot dipping 55% Al-Zn-Si alloy cladding material is divided into the outer sphere and inner layer the two major parts.
The weight ratio and volume ratio of AL are greater than the Zn in this cladding material, so CAMELSTEEL think that its structure is closer to the galvalume layer, but more complex than the galvanized layer and the galvalume layers.
In its core compound layer, besides it has the same Al－Fe compound layer diffuse formed by Al－Fe with galvanized layer, Si firstly forms the Fe－Si compound layer on the surface of steel base because of entering a certain amount of Si. That make the Al－Fe compound layer become thin, thus improve its processability.
This surface coating is very complex, but just right. A large amount of aluminum first crystallized, forming a very fine aluminum-rich dendrites, accounting for about 80% of the volume. It formed a fine network skeleton in the entire coating. In its remaining area, only about 20% intergranular interstices are zinc-rich eutectic structure.
The organic combination of the two organizations makes the coating have a good overall performance. Al-rich dendritic network laid the coating possess good corrosion resistance and thermal oxidation resistance of aluminum plate. The intergranular zinc-rich structure also gives the coating anodic protection effect as well as galvanized sheet after scratching.
Moreover, the film produced by the corrosion is retained by the aluminum-rich network, filled in the network gap between the dendrites, and forms a protective film with a certain protective effect on the surface of the coating to slow the corrosion rate. So its corrosion resistance has greatly improved than the galvanized layer with same thickness.
