Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D3/00—Electroplating: Baths therefor
  • C25D3/02—Electroplating: Baths therefor from solutions
  • C25D3/12—Electroplating: Baths therefor from solutions of nickel or cobalt

Definitions

• the stress of nickel deposits from plating solutions can be altered from tensile to near zero, and also to compressive stress by adding to nickel plating baths, such as those containing nickel sulfate and nickel bromide, amino naphthalene diand tri-sulfonic acids, and naphthol disulfonic acids and their salts, such as, for example, 3- amino-2,7-naphthalenedisulfonic acid, and 2-naphthol-6,8- disulfonic acid, and their sodium and nickel salts.
• nickel plating baths such as those containing nickel sulfate and nickel bromide, amino naphthalene diand tri-sulfonic acids, and naphthol disulfonic acids and their salts, such as, for example, 3- amino-2,7-naphthalenedisulfonic acid, and 2-naphthol-6,8- disulfonic acid, and their sodium and nickel salts.
• nickel salts of the above sulfonic acids are used as plating solutions rather than in the small amounts require as additive, bright of semibright, adherent and nonporous nickel deposits are formed and the stress of such nickel deposits range from approximately zero p.s.i. to 26,000 p.s.i. (compressive). Similar results were also obtained with the nickel salts of benzenesulfonic acid, 'benzenedisulfonic acids, naphthalenesulfonic acids, and naphthalenedisulfonic acids. Preferably all plating solutions contain nickel bromide. These plating solutions can be used for electroplating nickel on any substrate, including uranium.
• This invention relates to the electrodeposition of nickel from aqueous baths onto uranium or other substrates, using nickel organo-sulfonates as plating solutions or using the organo-sulfonic acids or their soluble salts as additives to known nickel plating solutions.
• uranium fuel elements used in water cooled nuclear reactors be protected from corrosion.
• One method is to clada nickel plated fuel element with aluminum.
• the nickel plate acts as a diffusion and secondary corrosion barrier, prevents the formation of undesirable aluminum-uranium compounds, and the uranium-nickelaluminum bond formed in the cladding operation provides good heat transfer.
• the reliability of the fuel elements is a very important factor in the operation of a nuclear reactor. Any technique which will increase the integrity of the fuel elements will lower the cost of operation.
• One problem associated with the use of nickel electrodeposited from conventional plating solutions used in nuclear processes is that the nickel has high residual stresses which can contribute to poor adherence of the deposit, thus providing poor heat transfer in the fuel element.
• novel plating solutions disclosed herein were developed to improve the heat transfer properties of the uranium-nickel-aluminum bond by controlling the stress of the nickel deposit.
• Another application of these plating solutions is in electro-forming articles, where control of stress is necessary if the product must meet close tolerances.
• Still another use of these plating solutions is in the deposition of low stress nickel coat under chromium, which can lower the stress of the chromium deposit.
• these plating solutions can be useful in any situation where nickel needs to be deposited under controlled stress.
• these plating solutions can be used to produce semibright and mirror bright nickel deposits for decorative purposes.
• Some of these nickel organo-sulfonates used to make up the plating solutions can be used as additions to conventional plating solutions. From these solutions bright and semibright nickel plates with reduced stress can be deposited.
• reduced stress of nickel deposits are obtained by adding to known aqueous acidic nickel plating baths an organic sulfonic acid or its soluble salt, particularly a sodium or nickel salt selected from one of the groups of organosulfonic acids given below:
• GROUP I R l I R R wherein two or three of the R groups are SO H and one of the R groups is NH and the remaining R groups are H.
• An example of one of these acids is 3-amino-2,7- naphthalenedisulfonic acid.
• R groups wherein two of the R groups are SO H and one R group is --O'H the remaining R groups being H.
• An example of one of these acids is 2-naphthol-6,8-disulfonic acid.
• nickel plating baths which have substantially zero stress of nickel deposits or which can even be under compression, comprise one or more of the nickel salts of a sulfonic acid of Group I and Group II, above, or a nickel salt of one of the group of organic sulfonic acids iven below:
• GROUP III m-benzenedisulfonic acid p-benzenedisulfonic acid o-benzenedisulfonic acid GROUlP 1V benzenesulfonic acid GROUP V l-naphthalenesulfonic acid Z-naphthalenesulfonic acid GROUP VI 1' ⁇ . 1?.
• Nickel (II) salt of 2-naphthol-6,8-disulfonic acid 2-naphthol-6,8-disulfonic acid
• Nickel bromide 0.1 M pH: 2.1 Temperature: 50 C. Current density: 30 rna./cm. Properties of the nickel deposit:
• Nickel (II) salt of m-benzenedisulfonic acid 0.7 M Nickel bromide: 0.1 M pH: 3.5 Temperature: 50 C. Current density: 30 ma./crn. Properties of the deposit:
• Nickel (11) salt of benzenesulfonic acid 0.4 M
• Nickel bromide 0.1 M pH: 2.5
• Temperature 50 C.
• Current density 30 ma./cm.
• Nickel (11) salt of 1 naphthalenesulfonic acid
• Nickel (II) salt of 2,7-naphthalenedisulfonic acid
• the sulfonates from Groups I and II were found to be novel additives to existing plating solutions. By using these compounds as additives We found that the stress of the nickel deposits from the plating solutions could be altered from tensile to near zero, and also to compressive stress.
• An example of a stress reducer from the two groups is shown below, and stress of the deposits are compared to deposits from the reference Watts-bromide plating solution Reference plating solution (Watts-bromide) Nickel sulfate: 1.2 M Nickel bromide: 0.20 M Boric acid: 0.62 M Temperature: 52 C. pH: 4.0 Current density: 60 ma./cm. Stress: 18,000 p.s.i. Group I.Additive to reference plating solution:
• Nickel (II) salt of 3-amino-2,7-naphthalenedisulfonic acid .05 M Stress: 12,000 p.s.i. Change in stress: 30,000 p.s.i. more compressive Group II.--Additive to reference plating solution:
• Nickel (II) salt of 2-naphthol-6,8-disu1fonic acid
• organo sulfonates from Group I and Group II can be used as brighteners for existing plating solutions. An example from each group is shown below.
• Nickel sulfate 1.2 M
• Nickel (H) salt of 3-amino-2,7-naphthalenedisulfonic acid 0.05 M
• Carbon content 1250 p.p.m.
• Nickel sulfate 1.2 M Nickel br0mide:0.2-0 M Nickel (II) salt of 2-naphthol-6,8-disulfonic acid:
• M mols per liter.
• ma./cm. milliamperes per square centimeter.
• the organosulfonic acid itself or other soluble salts thereof may be used, the sodium salts and nickel salts being preferable.
• organo-sulfonic acids or salts when used as additives, they may be added to any of the common plating solutions such as those comprising nickel sulfate, nickel. sulfamate, nickel bromide, nickel fluoborate and nickel chloride or other nickel salts or mixtures of such salts, preferably with buffer materials as, for example, boric acid.
• the amounts of such nickel salts which may be employed are quantities which are now conventional in this art for such baths.
• the plating solution to which the Group I or Group II compounds or salts are added comprises nickel sulfate and nickel bromide.
• the concentrate of organo-sulfonic acid for sulfonate may suitably range about 0.01 mol per liter to about 0.1 mol per liter, but there is no critical upper limit and they can be used up to saturation concentration value.
• the nickel salt of the organo-sulfonic acid of Group I and Group II is preferably used with nickel bromide.
• concentration of the nickel sulfamate may suitably range from about .1 mol per liter to 1.0 mol per liter and up to saturation, and the nickel bromide from preferably .05 mol per liter to 0.2 mol per liter.
• the baths are aqueous solutions on the acid side, such as those of a pH of 2.0-6.0.
• The. baths of this invention can be used for electroplating nickel or any substrate, including uranium, by means well known to the art for electroplating nickel from nickel plating baths.
• Current densities of 30 milliamperes per square centimeter-60 milliamperes per square centimeter (30 ma./cm. -60 ma./cm. are suitable as sho wn in the examples.
• Higher current densities can be used, such as 50-400 amperes (sq. dm.) particularly with agitation of the bath.
• a bath for depositing nickel plate consisting essentially of an aqueous acidic solution of at least one nickel salt selected from the group consisting of nickel sulfate, nickel sulfamate, nickel bromide, nickel fiuoborate, and nickel chloride, and contained dissolved in said nickel plating solution in a concentration of about .01 mol per liter to saturation, a compound selected from the group of organic sulfonic acids and their salts in which the organic sulfonic acid is selected from the group of compounds having the formula It it wherein two of the R groups are SO H and one R group is OH, the remaining R groups being H.
• a bath for depositing nickel plate consisting essentially of an aqueous acidic solution of at least one nickel salt of an organic sulfonic acid selected from the group of compounds having the formula I l R R wherein two or three of the R groups are --SO H and one of the R groups is NH and the remaining R groups are l I R R wherein two of the R groups are SO H and one of R group is OH, the remaining R groups being H,
• a method of electrodepositing nickel comprising the step of electrodepositing nickel from the solution defined in claim 1.
• a method of electrodepositing nickel comprising the step of electrodcpositing nickel from the solution defined in claim 2.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Electroplating And Plating Baths Therefor (AREA)

Applications Claiming Priority (1)

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Cited By (7)

Families Citing this family (2)

• 1971
  • 1971-04-23 US US00137062A patent/US3726768A/en not_active Expired - Lifetime
• 1972
  • 1972-04-12 BE BE781965A patent/BE781965A/fr unknown
  • 1972-04-19 DE DE19722218967 patent/DE2218967A1/de active Pending
  • 1972-04-21 FR FR7214290A patent/FR2134419B1/fr not_active Expired

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