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Plating surface treatment

  • Author:naky
  • Source:www.diecastingpartsupplier.com
  • Release on:2015-12-03
Refers to salts plating solution containing a pre-metallized, the matrix metal to be plated as a cathode through electrolysis, the bath in the pre-plating metal cation in the matrix metal deposited on the surface, forming a surface processing method of coating . Unlike the base metal coating performance, with new features. According to the coating function into protective coatings, decorative coatings and other functional coatings.

Electroplating is an electrochemical process, but also a redox process. The basic process of electroplating is the part immersed in a metal salt solution as a cathode, a metal plate as an anode, followed by a DC power supply, the deposition of the desired part coating.
For example: When nickel, cathode parts to be plated, pure nickel anode plate, respectively, in the following reaction occurs extremely yin and yang:

Cathode (plated): Ni2 ++ 2e → Ni (main reaction)
2H ++ 2e → H2 ↑ (side effects)
Anode (nickel plate): Ni -2e → Ni2 + (main reaction)
4OH - 4e → 2H2O + O2 (side effects)
Not all of the metal ions from the aqueous solution can be deposited, if the cathode hydrogen ions are reduced to hydrogen dominant side reaction, it is difficult to precipitate the metal ions on the cathode. According to the experimental possibilities, metal ions from an aqueous solution of electrodeposition It can be obtained from certain rules in the periodic table, as shown in Table 1.1.
Anode into soluble anodes and insoluble anodes, as with most of the anode coating corresponding soluble anodes, such as: galvanized zinc anode, silver for the silver anode, tin - tin-lead alloys - Lead alloy anode but few plating. Since the anodic dissolution difficulties, the use of insoluble anodes, such as acidic gold using a multi-platinum or titanium anode master bath salt ions by adding a good gold standard solution preparation to supplement chromium plating anodes using pure lead, lead - tin alloy, lead - antimony