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Protection of Plated Films from Corrosion

IP.com Disclosure Number: IPCOM000080596D
Original Publication Date: 1974-Jan-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Barclay, DJ: AUTHOR [+5]

Abstract

Electroplated films which are susceptible to corrosion are protected by further plating of a protective metal coating from the same bath as the original films, by varying the applied potential. Since the article is neither removed from the bath nor disconnected from the electric circuit during plating, corrosion has no chance to occur.

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Protection of Plated Films from Corrosion

Electroplated films which are susceptible to corrosion are protected by further plating of a protective metal coating from the same bath as the original films, by varying the applied potential. Since the article is neither removed from the bath nor disconnected from the electric circuit during plating, corrosion has no chance to occur.

Specifically, a nickel-iron plating bath includes:- NiCl(2).6H(2)O 200 gm/l FeSO(4).7H(2)O 5.56 gm/l Boric acid 25 gm/l Saccharin 2 gm/l PdCl(2) 0.0018 gm/l.

So-called "potentiostatic" plating is employed, in which the potential difference between the cathode and a standard calomel electrode (SCE) is kept constant by controlling the voltage applied between the anode and cathode. Initially, the cathode potential is held at -95O mV with respect to the SCE and a predominantly nickel-iron film is deposited. A small amount of palladium (less than 0.5%) is incorporated in the film, but does not significantly affect the magnetic properties. Subsequently, the potential difference is altered to -500 mV which causes the deposition of pure palladium. Agitation of the solution produces more rapid deposition of palladium and a protective coating may be formed in 3- 6O minutes.

It is not absolutely necessary that potentiostatic plating be employed, and protective films can be plated from arrangements which do not have reference electrodes by adjusting the plating current to an appropriate low value.

Othe...