During nickel plating, the cathode is the part to be plated and the anode is a pure nickel plate. The following reactions occur at the cathode and anode respectively: cathode (plated part): Ni2++2e → Ni (main reaction); 2H++2e → H2 ↑ (side reaction); Anode (nickel plate): Ni-2e → Ni2+(main reaction); 4OH - 4e → 2H2O+O2+4e (side reaction) Not all metal ions can be deposited from aqueous solution. If the side reaction of hydrogen ion reduction to hydrogen on the cathode is dominant, it is difficult for metal ions to precipitate on the cathode. According to the experiment, the possibility of metal ions electrodepositing from aqueous solution can be obtained from the periodic table of elements.
The anode is divided into soluble anode and insoluble anode Electroplating wastewater zero discharge manufacturer Most anodes are soluble anodes corresponding to the coating, such as zinc anode for zinc plating, silver anode for silver plating, and tin lead alloy anode for tin plating. However, a few electroplating uses insoluble anodes due to the difficulty of anode dissolution, For example, platinum or titanium anodes are mostly used for acid gold plating. The main salt ions of the plating solution are supplemented by adding the prepared standard gold containing solution. Pure lead, lead tin alloy, lead antimony alloy and other insoluble anodes are used for chromium plating.
The waveform of DC power supply has a prominent impact on the quality of electroplating. Among various electroplating processes, chromium plating is one of the most affected by the waveform of power supply. Low ripple DC power supply must be used for chrome plating, Electroplating equipment Otherwise, the bright range is narrow, and the coating is easy to be blurred and grayed. When high-efficient hard chromium plating additives are used, micro crack chromium layer is produced. When the output ripple is too large, the cracks are not fine and distributed evenly, and the required number of cracks cannot be reached.
Bright copper plating has a rule: from the Hull cell test piece, the greater the cathode current density, the better the brightness and flatness of the coating; The lower the current density, the worse the brightness leveling. Try to expand the brightness range in the low current density area, and reduce the brightness in the high current density area at the same time. The brightness is best uniform. In practice, using the same formula, process conditions, and brightener, the brightness flatness and brightness range may be significantly different, which is greatly related to the ripple coefficient of the DC power output.
