Methods of coating pretreatment and post-treatment of vacuum coating machine
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1. Pretreatment before plating: the purpose of pretreatment before plating is to get a clean and fresh metal surface, so as to prepare a high-quality coating after z*. The steps are as follows:
The first step; The surface roughness can be achieved by means of surface polishing and polishing.
The second step. Degreasing can be achieved by solvent dissolving, chemical and electrochemical methods.
The third step. Rust removal, can be mechanical, pickling and electrochemical methods; The fourth step; Activation treatment, generally in the weak acid erosion for a certain time before the activation treatment.
2. Post-plating treatment;
(1) passivation. The so-called passivation treatment refers to the surface treatment method of forming a solid and dense film with high stability on the coating by chemical treatment in a certain solution. Passivation can greatly improve the corrosion resistance of the coating and increase the surface gloss and anti-pollution ability. This method is widely used, Zn, Cu and Ag plating, passivation can be carried out.
(2) dehydrogenation. Some metals, such as zinc, in the process of electrodeposition, in addition to its own deposition, will also precipitate part of hydrogen, this part of hydrogen infiltration into the coating, so that the plating parts have brittleness, or even fracture, known as hydrogen embrittlement.