Zinc coated sheet that extends the life of the product and helps prevent corrosion. With greater heat reflection and attractive appearance, it is ideal for the construction of industrial buildings, silos, barns, among other applications.contributes to reflecting heat.
Rectangular corrugated galvanized sheet with high resistance to corrosion, ideal for the construction of roofs and industrial facades. With a long useful life, it is resistant to humid environments and
Galvanizing is an economical and effective method to prevent corrosion of steel, and the thickness of galvanized steel is generally 0.35 to 3 mm. The English "galvanizing" means that the galvanized layer can electrochemically protect the steel plate. In 1742, the French Meloman (Melomin) successfully studied the hot-dip galvanizing method. In 1836, the French Sorel (Sorel) applied the hot-dip galvanizing method to industrial production. In 1837, H. W. Grawford obtained a patent for hot-dip galvanizing by flux method. In 1935, American Sendzimir (T. Sendzimir) proposed to use protective gas reduction method for continuous hot-dip galvanizing of strip steel, commonly known as "Sendzimir method". In 1937, the first Sendzimir continuous hot-dip galvanizing line was built in the United States. China started producing hot-dip galvanized sheets in Anshan in the 1940s, and in 1979, the first continuous hot-dip galvanizing line for strip steel was built in Wuhan。
There are two kinds of hot-dip galvanizing method and electroplating method. The thickness of hot-dip zinc layer is generally 60 ~ 300g/m2 (single side), which is used for parts that require strong corrosion resistance. The electroplated zinc layer is 10-50g/m2 (single side), which is mostly used for painted parts or unpainted parts that do not require high corrosion resistance. The hot-dip method is divided into flux method and protective gas reduction method according to the pretreatment method. The flux method is to pickle the annealed steel plate to remove oxides on the surface, then pass through a flux tank containing ZnCl2 and NH4Cl, and then enter the molten zinc tank for galvanizing. The protective gas reduction method is widely used for continuous hot-dip galvanizing of strip steel. The strip steel first passes through the flame-heated preheating furnace to burn off the residual oil on the surface, and at the same time, an iron oxide film is formed on the surface; Sponge Iron. After the strip steel whose surface has been purified and activated is cooled to a temperature slightly higher than that of molten zinc, it enters a zinc pot at 450-460°C, and uses an air knife to control the thickness of the zinc layer. Finally, it is passivated with a chromate solution to improve white rust resistance.
According to the plating solution used, it can be divided into alkaline method and acid method. The alkaline plating solution has high price, pollutes the environment, low production efficiency, and poor coating quality, so it is actually not used. The main components of the acid plating solution are ZnSO4·7H2O, NH4Cl and Al2(SO4)3·18H2O, etc. With pure zinc as the anode and strip steel as the cathode, under the action of current, the zinc anode plate is dissolved into Zn2+ into the plating solution, and Zn2+ is reduced to metallic zinc at the cathode and deposited on the surface of the strip steel. The coating is treated with a mixed solution of phosphate and chromate, which can improve the paintability, and the surface of the electro-galvanized steel sheet is bright and smooth, which was mainly used in the automobile industry in the past. In recent years, the scope of application has been expanded to the electrical industry and other aspects, which has promoted the development of the electro-galvanized sheet industry. In the 1970s, single-sided galvanized sheets were also developed.
Post time: Mar-10-2022