Main application industries of galvanized sheet: a large number of galvanized sheet are used in automobile manufacturing, refrigerated box, construction industry, ventilation and heating facilities, furniture manufacturing and other fields. Zinc plating has become an important anti-corrosion method for iron and steel, not only because zinc can form a dense protective layer on the steel surface, but also because zinc has cathodic protection effect. When the zinc coating is damaged, it can still prevent the corrosion of iron base metal by cathodic protection.In recent years, with the development of zinc plating process and the use of high-performance brightener for zinc plating, zinc plating has changed from simple protection purpose to protection decoration application. There are two kinds of zinc plating solution: cyanide plating solution and non cyanide plating solution. Cyanide plating bath is divided into micro cyanide, low cyanide, medium cyanide, and high cyanide. Cyanide free plating solutions include alkaline zincate bath, ammonium salt plating solution, sulfate plating solution and ammonia free chloride plating solution. Cyaniding zinc plating solution has good plating ability and smooth and fine coating, which has been used for a long time in production. However, due to its high toxicity and serious environmental pollution, low cyanide, micro cyanide and non cyanide zinc plating solutions have been adopted in recent years.