There are two production methods: hot plating and electroplating. The tin layer thickness of hot plating method is
thick and uneven, the coating thickness is difficult to control, the tin consumption is large, the efficiency is low, and
its application is limited, so it is gradually eliminated by electroplating method. Electroplating method is the
use of electroplating process on the steel plate substrate uniformly plated with tin film, high productivity, low
cost, thin and uniform coating, can produce different coating thickness, can also be single-sided or double-
sided plating. Electroplating methods mainly include alkaline electroplating, sulfate electroplating, halogen
electroplating and boron fluoric acid electroplating.
Acid electroplating
The most common application of acid plating method is Frostam type, accounting for about 70% of the total number of operating lines. This method has high current efficiency and current density, moderate operating temperature and easy control. Operation line speed up to 450m/min.
The borofluoric acid plating solution in the acid process line, that is, the Lasserstein type, is a unique production form in West Germany, which has a high current density bearing capacity and cathode efficiency, and can be operated at low temperature, but the preparation of the plating solution is more complicated and the corrosion resistance is high. Unit speed up to 500m/min. At present, including the operation line introduced by China's WisCO, there are about 17 such operation lines in the world, mainly in West Germany.
Halogen electroplating
Halogen electroplating method is horizontal working line. Current density can reach 40~60A/dm2, high cathode efficiency, low temperature operation, strong electrolyte corrosion, unit speed up to 760m/min, characterized by high productivity. At present, there are more than 20 operating lines with different speeds of 300~760m/min, mostly concentrated in the United States [2].
Basic electroplating
Alkaline electroplating method with sodium stannate as the electrolyte, the current density, production speed and current efficiency are low, but the corrosion is general, the process is old, and the current online production is not much.
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