When we use chrome plating additives, we will find that the anode plate used for chrome plating is special, which is insoluble anode plate such as lead and lead alloy.Why is this?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product chromium plating additive Cr-9,there are three main reasons:
1. If chromium is used as anode during chromium plating, the current efficiency of anode can be close to 100%, while the current efficiency of cathode is only 8~13%. The concentration of chromium will increase continuously.
2. The electroplated chromium layer is directly reduced by hexavalent chromium, and the chromium dissolved in the chromium anode has different valence states, mainly trivalent chromium, which will lead to the rapid increase of trivalent chromium in the plating solution, while hexavalent chromium will continue to decrease, which is easy to cause failures.
3. Chromium metal is very brittle and difficult to form and machine.Generally, pure lead, lead antimony or lead tin alloy are used as anodes. The plating solution is highly corrosive to the anode, and pure tin is easy to be corroded and dissolved. Therefore, lead alloys containing antimony or tin 6~8% have good corrosion resistance and are widely used in production.
In the production process, there will be a yellow film on the surface of the lead anode used, which will not affect the conductivity of the plating solution.During shutdown, the lead anode shall be taken out in time, otherwise, the lead dioxide in the chromium plating solution is easy to be converted into dense lead chromate, resulting in poor conductivity of the plating solution, increased tank voltage and increased power consumption.
This is the particularity of using lead or lead alloy as anode when using chromium plating additives. In addition, the area ratio of cathode and anode should be controlled to ensure the conductivity of plating solution and maintain the content of trivalent chromium.If you are interested in chromium plating additives, please contact the Bigolly customer service for free samples and detailed technical information!
If you want to know more about chrome plating, you can click to view the "Electroplating encyclopedia".