Passivation is the last step in chemical cleaning, mainly suitable for stainless steel, aluminum, copper, zinc alloy and other metal materials. And it is a key step for surface finishing.
The purpose is to prevent corrosion of materials. For example, after the boiler is pickled, rinsed, the metal surface is very clean, very activated, and easily corroded, so it must be passivated immediately.
The function of the passivation process is to form a passivation film on the metal surface, which effectively hinders the contact between the metal surface and air, thereby enhancing the corrosion resistance and rust resistance on the metal surface, and increasing the salt spray test value for more than 72-100 hours. The passivation process is chromate passivation, which can be used for natural passivation or lightly colored passivation. After passivation, a complex passivation film will be formed on the surface of the metal workpiece, which can effectively protect the metal surface and self-repair.
When some micro areas on the surface are destroyed, the various ions fixed inside the passivation film will react with the metal surface again, forming a new passivation layer. Because chromate passivation has the advantages of good effect, self-healing, corrosion resistance, wear resistance, salt spray resistance, etc., it is widely used in metal passivation process.
We do cleaning, oil removal and rust removal, as the pretreatments, which can effectively remove impurities and oxides on the metal surface.
We put it into a chromate passivation solution for passivation. The ph value of chromate in the passivation solution is an important parameter that needs attention and control. Only by controlling the ph value within the range, can we get the best passivation effect. Finally, we do washing and drying.
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