Working principle of electroplating

- Feb 06, 2018 -

Electroplating requires a low-voltage high current power supply to the electroplating trough and an electrolytic device composed of electroplating solution, the parts to be plated (cathode) and the anode. The electroplating liquid composition depending on the coating is different, but all contain the main salt to provide metal ions, complexing agents that form complexes of metal ions in the main salts, buffers for stabilizing the ph of solutions, anode activator and special additions (such as brightener, grain refiner, leveling agent, wetting agent, stress eliminator, and mist suppression agent). Electroplating process is the metal ions in the bath under the action of the external electric field, through the electrode reaction to restore the metal atoms, and on the cathode metal deposition process. Therefore, this is a metal electrodeposition process including liquid mass transfer, electrochemical reaction and electrochemical crystallization.

In the plating bath containing electroplating liquid, after cleaning and special pretreatment of the plating parts as the cathode, the metal is made into anode, the two poles are respectively connected with the positive and negative electrode of DC power supply. The electroplating solution consists of aqueous solutions containing metal-plated compounds, conductive salts, buffers, ph regulators and additives. When energized, the metal ions in the electroplating solution move to the cathode to form a coating under the action of potential difference. The anode metal forms metal ions into the electroplating solution to maintain the concentration of the metal ions being coated. In some cases, such as chrome, is the use of lead, lead-antimony alloy made of insoluble anode, it only acts as a transfer of electrons, conduction current role. The concentration of chromium ions in the electrolyte should be maintained by adding chromium compounds to the plating bath on a regular basis. When electroplating, the quality of anode material, the composition of electroplating solution, temperature, current density, ohmic time, stirring intensity, impurities, power waveform and so on will affect the quality of coating, need to be controlled timely.

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