There are two types of chromium plating; one is industrial and the other being decorative.
Industrial chromium plating is divided into two such as hexavalent and the other being trivalent plating. The decorative plating is a mixture of chrome and nickel.
It has a mirror finish. Its thickness range from 0.002 to 0.020 miles. In jewelry, plastic knobs, hardware and hard tools the decorative chrome is used.
The process for hexavalent chromium is first the activation bath is done, and then chromium bath then it is rinsed twice. While using activation bath a separate tank of chromic acid is used.
Occasionally the activation step takes place in the chromium bath itself. Other than bath the other important things that matter are temperature and current density.
These two affects the brightness and coverage. Trivalent chromium plating process is divided into three such as the single electrolyte bath is done then sulfate based bath using shielded anodes and at last sulfate based using insoluble catalytic anode.
The trivalent chromium plate has higher efficiency cathode compared to hexavalent chromium plating which has lower efficiency cathode.
Trivalent chromium has a lower concentration in chromium bath while hexavalent chromium has a higher concentration.
Comments
Post a Comment