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Hot-dip galvanizing company The role of hot-dip galvanizing channel steel plating agent

Release date:2018-06-01 author: click:

Hot-dip galvanizing company The role of hot-dip galvanizing channel steel plating agent


The role of hot-dip galvanizing channel steel plating agent


The so-called co-plating is the process of immersing the pickled parts into a certain composition of zinc chloride ammonium plating solution, and then forming a thin film of zinc chloride ammonium salt on the surface of the workpiece.


Effect of plating


1) Clean the surface of the steel, remove the iron salt or oxide remaining on the surface of the reworked part after hydrochloric acid washing, so that the steel sheet can enter the zinc bath for maximum surface activity.


2) A layer of salt film is deposited on the surface of the reworked part to prevent rust in the air from the plating bath to the zinc pot.


3) Purify the liquid zinc in the zinc bath, so that the parts and liquid zinc quickly infiltrate and reflect.


Activation of surface-coated zinc chloride ammonium salt film


1] Below 200 °C, a complex hydrochloric acid is formed on the surface of the part, the approximate form is H2[Zn2CL2], which is a strong acid, so as to ensure that the surface of the surface can not form an oxide film during the re-drying process and maintain the activation state.


2] When the temperature is above 200 °C, the NH4CL in the salt film of the surface assisting solution will be decomposed into NH3 and HCL at a higher temperature. At this time, the corrosion of the steel matrix by HCL is dominant, so that the surface of the steel substrate cannot form oxide. , to maintain the activation state of the steel matrix. Therefore, the correct use of NH4CL-containing plating agent in hot dip galvanizing is very heavy.