One, the nature is different
1, pickling: the use of acid solution to remove the surface of iron and steel oxide and rust, a method of cleaning the surface of metal.
2. Passivation: the process in which the metal is oxidized by strong oxidant or electrochemical method to make the surface become inactive or dull.
Second, the principle is different
1, pickling: generally will be immersed in sulfuric acid and other aqueous solution, in order to remove metal surface oxide film.
It is the pretreatment or intermediate treatment of electroplating, enamel, rolling and other processes.
2, passivation: metal due to the action of the medium generated by the corrosion product if there is a dense structure, formed a layer of thin film (often invisible), closely covered in the surface of the metal, the change of the surface state of the metal, the metal electrode potential to the positive direction of jump, and become a blunt corrosion resistance.
Third, the process is different
1, pickling: stainless steel pieces of the hang – chemical degreasing (in addition to conventional alkaline chemical oil removal or surfactant oil) the first step to hot water washing, water washing and acid pickling to wash water, the second step to wash water, into the next process (such as: chemical coloring to recycling, water wash to hardening treatment, water wash to closed treatment to water washing, drying, finished products)
2, passivation: stainless steel workpiece before pickling passivation, such as surface dirt, should be through mechanical cleaning, and then degrease in addition to oil.
If the oil cannot be removed by the acid-wash solution and the passivation solution, the presence of oil on the surface will affect the quality of the pickling and passivation. Therefore, the degreasing of oil cannot be omitted. Alkali solution, emulsifier, organic solvent and steam can be used.
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Post time: Nov-12-2019