Generally the passivation treatment after plating, passivation can increase the surface protection of the product performance and aesthetics.

Metal cover a lot of more phyletic, for spring, usually use the method of plating for metal protective layer. Plating layer can not only protect from corrosion, and at the same time can improve the appearance of the spring. Some electroplating metal also can improve the working performance of spring, such as to improve the surface hardness, increased wear resistance, improve the thermal stability, prevent rays, corrosion, etc. But if it's purely for spring corrosion, generally choose the electricity galvanized layer with cadmium plating layer.