The chromium plating layer has good hardness, wear resistance, corrosion resistance and decorative appearance. It is widely used as the outer layer and functional coating of the protective-decorative coating system. It has always occupied an important position in the electroplating industry. At present, chromium plating has become one of the most widely used plating types in the industry. For a long time, hexavalent chromium has been used for chromium plating, but it is highly toxic and pollutes the environment seriously, so a trivalent chromium plating process was developed.
Advantages of trivalent chromium plating process:
Low toxicity and little pollution. The cleaning water of the plating solution does not contain hexavalent chromium, the wastewater can be discharged after a little treatment, and the electroplating process does not produce toxic chromic acid mist;
The concentration of the plating solution is low, only 1/10 of hexavalent chromium plating, with good dispersion and coverage capabilities, and improved yield;
The electroplating process is not affected by current interruptions and does not require stripping;
The cathode current efficiency can reach 21-25%, which is higher than hexavalent chromium plating, improving productivity.
Problems with trivalent chromium plating process:
It is difficult to increase the thickness of the coating. It can only be used for decorative chrome plating, but cannot be used for thick chrome plating. Functional chrome plating is difficult;
The plating solution has complex components and poor stability; it has low tolerance for impurities and is difficult to maintain;
There are shortcomings in the selection and use of anodes, and corrosion resistance, hardness, and impact resistance need to be improved;
When decorative chrome plating is used, the appearance color is unsatisfactory.
The primary equipment investment is large and the cost is high.