The reason why sheet metal chassis processing uses galvanized tin plating

Now sheet metal chassis, generally with galvanized steel plate manufacturing. The reason why the steel plate is galvanized is mainly for corrosion protection. But because zinc is not easy to oxidize metal, so galvanized steel can be isolated from the air, to achieve the purpose of corrosion prevention, this understanding is wrong; In fact, the opposite is true. Zinc is a very reactive metal that is easily oxidized. But instead of being a loose powder like iron oxide, zinc oxide is a dense surface, and this layer of zinc oxide prevents further oxidation of the zinc inside.

For sheet metal case processing When the surface of galvanized steel plate is damaged and exposed to the internal iron surface, according to the principle of chemical batteries, zinc will oxidize before iron to protect the iron layer from damage because zinc is more active than iron. The combination of the two is the truth of galvanized steel plate protection. A good galvanized steel sheet should be grey and white matte, which is the color of the zinc oxide surface.

Some chassis of poor material use poor quality galvanized steel, even tinned steel plate. The product generally has a thin, uneven coating. Especially tinned steel, if the tin layer is not damaged, everything will be fine. However, once the tin layer is damaged, the iron will become the protection of the tin, rather than the pure steel plate paint, because tin is an inert metal.