Wednesday, March 26, 2008

Chloride Baths of Nickel Plating

Posted by Electroplating Process.

When work with an all chloride bath operated at the boiling point and other made a comprehensive study of the chloride boric acid electrolyte and the properties of the deposits produced. Deposits are smoother, fine grained, harder and stronger than those from Watts bath and more highly stressed. Although it is possible to operate this bath under conditions giving harnesses over 400 Vickers, such deposits are so highly stressed that they may crack spontaneously. High frequency periodic current reversal with relatively large amounts of depleting during each cycle resulted in soft ductile deposits with greatly reduced stress. High conductivity of the chloride bath permits operation at lower voltages, saving power costs. High current densities can be employed, anode and cathode efficiencies are high, and deposits have less tendencies to form pits, nodules, and tress.

Mention should be made of two other high chloride electrolytes, the chloride-sulfate and the chloride-acetate baths. Sulfate-chloride bath which overcome some of the disadvantages of the all chloride bath but retains many of the advantages. Aside from decorative plating with suitable organic addition agents, it has found some use in resizing worn parts.

The chloride acetate bath has low resistivity and produces deposits of moderate hardness and high tensile strength. It has found use in plating stereotypes and electrotypes, building up worn parts, and plating steel billets as a bonding layer before cladding and rolling.