Cold galvanizing is also called the electric galvanized, it is using electrolytic equipment fitting after degreasing, pickling, into the composition of zinc salt in the solution, and connect the cathode electrolytic equipment, across the tube placed zinco, connected to the anode electrolytic equipment, power supply is connected using current from the positive to the negative directional moving deposits a layer of zinc on the pipe fittings, cold is plated fittings galvanized after processing.Send InquiryChat Now
Galvanized steel strip line.
Chemical treatment in hot galvanizing is an electrochemical reaction.Cold galvanizing is a physical reaction, just a layer of zinc on the surface, so the zinc layer is easy to fall off.Hot galvanizing is used in construction.
In Galvanized steel strip line Continuous hot dip galvanizing process: steel - heating - cooling to galvanized temperature - galvanizing - cooling.
1. Hot galvanizing is developed by the older method of hot-dip galvanization. Since the application of hot-dip galvanizing to industry in France in 1836, it has been a hundred and forty years old.However, the hot galvanizing industry has been developing rapidly with the rapid development of cold rolled strip in the last 30 years.
The production process of hot galvanized sheet mainly includes: original preparation -- pre-galvanizing treatment -- hot dip plating -- post-treatment -- finished product inspection, etc.According to the custom, the hot dip galvanizing process is divided into two categories: line annealing and line annealing according to different pretreatment methods.
Wet method (single sheet steel hot galvanizing method)
Galvanized steel strip line Hot dip galvanizing method for annealed sheet steel.
Hot galvanizing (wheeling) method (strip steel continuous hot galvanizing method)
Sebdzimir (protection gas method) improved sendzimir method.
American steel union law (with kawasaki)
2,In Galvanized steel strip line line annealing is hot rolled or cold rolled into the galvanizing line before the first type annealing furnace in the bottom of a pump or bell type annealing furnace of recrystallization annealing, in this way, galvanizing line is no annealing process.Steel plate must maintain a clean pure iron active surface with no oxides and other dirt before galvanizing.This approach is to first by pickling method to remove the surface of the annealing tin oxide, and then coated with a layer of zinc chloride or ammonium chloride and zinc chloride mixed solvent composed of protection, to prevent the oxidation of the steel plate to be.
(1) wet method hot galvanizing: the solvent on the surface of the steel plate is not dry (i.e. the surface is still wet), and the zinc liquid with molten solvent is applied to the surface.
(2) the single plate: this method is generally adopted hot pack rolling plate as raw material, the first after annealing of steel plate into pickling workshop, with sulfuric acid or hydrochloric acid removal method of oxygen on the surface of galvanized sheet metal.After pickling, the steel plate immediately goes into the water tank to soak and wait for galvanization, which prevents the steel plate from reoxidation.After acid washing, water cleaning, drying, drying, into the zinc pot (temperature has been kept at 445-465 degrees Celsius) hot galvanizing, then oil and chromium treatment.This method has a significant improvement in the quality of zinc coated zinc plate, which has a certain value for small-scale production.
(3) wheeling hot: the continuous galvanizing line including alkali degreasing, hydrochloric acid, water washing, solvent coating, drying and so on a series of pretreatment process, and the original plate into galvanized in the galvanizing line is needed before the bell type annealing furnace.The production process is complex, the production cost is high, and the main product is that the products produced by this method often have solvent defects, which affect the corrosion resistance of the zinc coating.Moreover, AL in the zinc pot and the solvent on the surface of the steel belt are used to produce aluminium trichloride, and the adhesion of the coating becomes bad.Therefore, although this method has been published for nearly 30 years, it has not been developed in the world hot galvanizing industry.