Increasing the Bath Life and Quality of Trivalent Passivates on Zinc Plate
by Roger Sowinski
Vice President of Technology, Asterion

Q: What is the best way to increase the bath life and quality of trivalent passivates on zinc plate?

A: One of the more significant developments of the last 20 years in the metal finishing industry is the commercial development and application of trivalent passivates on zinc electroplate. These developments have allowed applicators to eliminate the use of toxic hexavalent-chromate conversion coatings, thereby safeguarding the health of all involved in the handling and processing of zinc-plated parts. Further, these trivalent passivates have a substantially positive impact on the environment. The following information addresses issues involved with producing a consistent blue-bright, thin-film passivate on electrodeposited zinc.

Trivalent passivates are typically acidic in nature and operate at a pH between 1.6 and 2.2, under most operating situations. Therefore, during the passivation step, both zinc and iron will be dissolved in the passivate solution, and their concentration in the passivating solution will increase. Read more.
Back to Basics: Rack or Barrel Electroplating?
Electroplating is a deposition process where a thin coating of metal is deposited on a surface by passing an electric current through a solution in which the plated part acts as the cathode. The anode is often composed of the metal being deposited. The solution, or plating bath, contains dissolved salts of the metals being deposited.

There are two basic deposition methods used for electroplating: rack and barrel Both methods work with a wide variety of plating technologies including gold, silver, zinc, nickel, tin, and copper. However, when choosing the best method for your specific application, there are distinct differences that should be considered. Read more.

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