CA1058553A - Electrodeposition of alloys of nickel, cobalt, or nickel and cobalt with iron - Google Patents

Abstract

ELECTRODEPOSITION OF ALLOYS OF NICKEL, COBALT, OR NICKEL AND COBALT WITH IRON

--- Abstract of the Disclosure - In accordance with certain of its aspects, this invention relates to a process for the preparation of an electrodeposit which contains iron and at least one metal selected from the group consisting of nickel and cobalt which comprises passing current from an anode to a cathode through an aqueous plating solution containing an iron compound and at least one member selected from the group consisting of cobalt compounds and nickel compounds providing cobalt or nickel ions for electrodepositing alloys of iron with cobalt and/or nickel and containing in combination an effective amount of:
(1) at least one member selected from the group of cooperating additives consisting of:
(a) primary brightener (b) secondary brightener (c) secondary auxiliary brightener (d) anti-pitting agent, and (2) an organic hydroxy-sulfonate compound of the formula:

wherein M is a cation having a valence of 1-2; k is an integer 1-2 corresponding to the valence of M; and R is hydrogen or a monovalent aliphatic group of 1-16 carbon atoms; and (3) an hydroxy carboxylate complexing compound or a polyol complexing compound selected from the group consisting of mannitol, sorbitol and dulcitol; and (4) an iodide of a bath compatible cation or a compound providing an iodide anion when plating cobalt-containing alloys;
for a time period sufficient to form a sound metal electroplate upon said cathode surface.

Description

~05~S53 ELECTRODEPOSITION OF ALLOYS OF NIGKEL, GOBALT
`OR NICKEL AND COBALT WITH IRON

This invention relates to improved processes and com-positions;for the electrodeposition of semi-bright or bright iron alloys with nickel or cobalt or nickel and cobalt. More particularly, this invention relates to the use of a new additive to improve the plating of iron-containing alloys of nickel, cobalt and nickel-cobalt.
Because of the much lower cost of iron and its salts as contrasted to that of nickel and cobalt and their salts it would be highly desirable to electrodeposit alloys of nickel or cobal~ or nickel and cobalt with iron containing an appreciable iron content thereby reducing metal and salt costs.
DETAILED DESCRIPTION
.
In accordance with certain of its aspects, this invention provides a process for the preparation of an electrodeposit which con-tains iron and at least one metal selected from the group consisting of nickel and cobalt which comprises passing current from an anode to a cathode through an aqueous plating solution as defined below for a time period sufficient to form a sound metal electroplate upon said cathode surface.
The aqueous plating solution according to the invention contains at least one ferrous compound and at least one member selected from the group consisting of nickel compounds and cobalt compounds providing nickel and/or cobalt ions for electrodepositing alloys of iron with nickel and/or cobalt, and containing in combination an effective amount of at least one member selected from the group con-sisting of:

B

~L051~5~3 ~a) primary brightener ~b) secondary brightener (c) secondary auxiliary brightener; and (d) anti-pitting agent; and an organic hydroxy-sulfonate compound of the formula:

~ R_~_so3_ M

wherein M is a cation having a valence of 1-2; k is an integer 1-2 corresponding to the valence of ~; and R is hydrogen or a mono-valent aliphatic group of 1-16 carbon a~oms; and an hydroxy carboxylate complexing compound or a polyol complexing compound selected from the group consisting of mannitol, sorbitol and dulcitol; and an iodide of a bath compatible cation or a compound providing an iodide anion when plating cobalt-containing alloys J
i.e. when the aqueous plating solution contains a cobalt compound.
For bright, well-leveled alloy plating primary brighteners such as diethoxylated 2 butyne-1,4-diol or dipropoxylated 2 butyne-1,4-diol may be used in cooperation with a ?

~5~3S53 sul~o-oxygen secondary brightener, preferably saccharin, a secondary auxiliary brightener and an anti-pitter. If full brightness and leveling are not desired a fairly lustrous deposit with fair leveling may be obtained using as a primary brightener a nitrogen heterocyclic compound such as N-allyl quinolinium bromide at a concentratlon of about 5 to 20 mg~l in cooperation with a sulfo-oxygen secondary brightener, a secondary auxiliary brightener and an anti-pitter.
The substrates on which the nickel-iron, cobalt-lron or nickel-cobalt iron containing electrodeposits of this invention may be applied may be metal or metal alloys such as are commonly elec~rodeposited and used in the art o~ electroplating such as nickel, cobalt, nickel-cobalt, copper, tin, brass, etc.
Other typical substrate basis metals from which articles to be plated are manufactured may include ferrous metals such as steel;
copper; alloys of copper such as brass, bronze, etc.; zinc, particularly in the form of zinc-base die castin~s; all of which may bear plates of o~er mekals, such as copper~ etc. Basis metal substrates may have a ~ariety of surface finishes depending on the final appearance desired, which in turn depends on such factors as lusterg brilliance, levelin~, thickness, etc. of the nickel-rion, cobalt-lron and nickel-cobalt-iron containing electroplate applied on such substrates.
me term "primar~ brightener" as used herein is meant to include plating additive compounds such as reaction products of epoxides with alpha-hydroxy acetylenic alcohols such as diethoxylated 2 butyne-1,4-diol or dipropoxylated 2 butyne-1,4-diol, other acetylenicsg N-he~erocyclics, active sulfur compounds dye-stuffs, etc. Specific examples of such plating additives are 1,4-di~ hydroxyethoxy)-2-butyne (or diethoxylated 2 butyne-1,4, diol) 1,4-di-(~-hydroxy-~f-chloropropoxy)-2-butyne 1,4-di~ r-epoxypropoxy)-2-butyne . 1,4-di-~-hydroxy~ butenoxy)-2-butyne 1,4-di-(2'-hydroxy-4'-oxa-6'-heptenoxy)-2~butyne N-1~2-dlchloropropenyl pyridinium chloride

2,4~6-trimethyl N propargyl pyridinium bromide N-allyl quinaldinium bromide N-allyl quinolinium bromide 2-butyne-1,4-diol propargyl alcoho~
2-methyl-3-butyn 2-ol thiodiproprionitrile [ /CHzCHs~

thiourea phenosafranin fuchsin When used alone or in combination, a primary brightener may produce no visual effect on the electrodeposit, or may produce semi-lustrous, fine grained deposits However, best results are obtained when primary bri~hteners are used with either a secondary brightener, a secondary auxiliary ~rlghtener, or both in order to provide optimum deposit luster, rate of brightening, le~eling, bright plate current denslty range, low current density coverage, etc.

~ 5~3553 The term "secondary brightener" as used herein is meant to include aromatic sulfonates, sul~onamides, sulfonimides, sul~inates, etc. Specific examples of such plating additives . are:
1. saccharin 2 trisodium 1,3,6-naphthalene trisulfonate

3. sodium benzene monosulfonate 4O diben~ene sulfonimide 5. sodium benzene monosulflnate Such plating add~tive compounds, which may be used singly or in suitable combinations, have one or more o~ the following functior. :
1. To obtaln semi~lustrous deposits or to produce substantial grain-refinement over the usual dull, matte, grainy, non-reflective deposits from additive-~ree baths.
2 To act as ductilizing agents when used in combination with other additives such as primary brighteners.
3. To control internal stress o~ deposlts, generally by making the stress desirably compressive.

4~ To introduce controlled sulfur contents into the electrodeposits to desirably af~ect chemical reactivity, potential dlfrerences in composite coating systems, etc. thereby decreaslng corrosion, better protecting the basis metal ~rom corrosion, etc.
qhe term "secondary auxiliary brightener" as used herein is meant to include aliphatic or aromatlc-allphatic olefinically or acetylenically unsaturated sul~onates, sulfo-namides, or sulfonimides, etc. Speci~ic examples of such plating additives are:
lo sodlum allyl sulfonate . 2. sodium-3-chloro-2-butene-1-sulfonate 3. sodium ~-styrene sul~onate 4. sodium propargyl sul~onate

5. monoallyl sulfamide fH2N-S02-NH-CH2-~H=C~z) 15 ` 6. diallyl sul~amide _ _ NN-Allyl .

. NH-Allyl 7O allyl sulfonamide Such compounds, which may be used singly (usual) or in combination have all of the functions given for the secondary brighteners and in addition may have one or more of the follo~ing functions~
1. They may act to prevent or minimize pltting (probably acting as hydrogen acceptors).

2. They may cooperate with one or more secondary brighteners and one or more primary brighteners to give much better rates o~ brightening and leveling than it would be posslble to attain with any one or any two compounds selected from all three o~ the classes:
~1) primary brightener, (2) secondary brightener; and (3) secondary auxiliary brightener used either alone or in combination.
3~ They may condition the cathode sur~ace by catalyt~c poisoning, etc. so that the rates of consumption of cooperating additives ~ (usually o~ the primary brightener type) may be substantially reduced, making ~or better economy o~ operation and control~
Among the secondary auxiliary brighteners one may also include ions or compounds Or certain metals and metalloids such as zinc, cadmium9 selenium, etc. which, although they are not generally used at present, have been used to augment deposit luster, etc. Other cooperating additives of organic nature which may be useful are the hydroxy sulfonate compounds of U. S.
Patent No. 3,697,391 i9e. typically, sodium formaldehyde bisulfite, the function of which is to make baths mcre tolerant ~ 1058553 to primary brightener concentrations, to increase tolerance toward metallic impurities such as zinc, etc., and, in this invention, to make the bath more tolerant to the complexing agent used and its concentration and also to the content of iron in the bath.
The term "anti-pitting agent" as used herein is an organic material (different rrom and in addition to the secondary auxiliary brigh~ener) whlch has surfactant properties and which ~unctions to prevent or minimi~e gas pitting. An anti-pitting agent may al~o function to make the baths more compatible with contaminants such as oilJ grease~ etc. by ~heir emulsifying, dispersing, solubilizing, etc. action on such contaminants and thereby promote attaining of sounder deposits.
Anti-pitting agents are optional additives which may or may not be used in combination with one or more members selected from the group consisting o~ a primary brightener, a secondary brightener, and a sec~ondary auxiliary brightener. Of the four classes of organic surfactants, i.e., anionic~ cationic, non-ionic or amphoteric~ the type commonly used for the electro-deposition of Ni, Co, Fe, or alloys thereof and for ~unctioning as anti-pltters is the anionic class. me anionic class individual members commonly used may be exemplified by the following:
sodium lauryl sulfate sodium lauryl ether sulfate sodium di-alkylsulfosuccinates sodlum 2-ethylhexyl sul~ate Typical nickel-iron-containing, cobalt-iron-containing, and nickel-cobalt-iron-containing bath compositions which may be used in combination with effective amounts of about 0.005-0.2 grams per liter of the primary brightener, with about 1.0-30 grams per liter of the secondary brightener, with about 0.5--10 grams per liter of the secondary auxiliary brlghtener, and with about 0.05-1 gram per liter of anti-pitting agent5 described herein, are summarized below. Combinations of prlmary brightener 3 and o~ secondary brighteners may also be used with the total 10. concentration of members of each class coming within the typical concentration limits statedO
The hydroxy-sulfonate additive compounds of the invention may be prepared according to ~he following general reaction:

H [ 3 ] I I -C-503 1 M

wherein M is a cation having a valence of 1-2; preferably M
~s an alkali metal or alkaline earth metal cation or ammonium;
k is an integer 1-2 corresponding to the valence of M; and R is hydrogen or a monovalent aliphatic groùp o~ 1-16 carbon atoms.
Typical nickel-containing, cobalt-containing, and nickel-cobalt-containing bath compositions also containing iron which may be used ~n combination with effective amounts of about 0.5-5 g/l of the hydroxy-sulfonate additive compounds and effective amounts of about 0.005-0.~ g/l of the primary 105~553 brighteners, with about 1.0-30 g~l o~ the secondary brightener, with about 0.5-10 g/l o~ the secondary auxiliary brightener, and with about 0.05-1 g/l of anti-pitting agent, described herei are summarized below. Boric acid should be present in an amount o~ ~rom 15 grams per llter to 60 grams per liter.
Mannitol, sorbitol and dulcitol are optical isomers having the ~ollowing ~ormula:

HOCHz(CHOH) 4 CH 2 OH

Mannitol, sorbitol, and dulcitol are used in single or combined concentration of 10 grams per liter to 60 grams per liter. Thei function in nickel 3 cobalt and iron alloys thereof plating baths have been disclosed in U. S. 3,804,726.
The aqueous bath compositions for electrodeposition of cobalt with iron or nickel and iron alloys may contain effective amounts o~ iodide from widely varying sources. Ionic iodide compounds have been found to be most preferred since the addition of such compounds has been found to be convenient and inexpensive. Any waker-soluble iodide having a bath-compatible cation associated therewith may be employed in amounts sufficien to provide enhanced cobalt-containing electrodeposits as compar0 to cobalt-containing electrodeposits which may be obtained in the absence of iodide ion. Typical iodide compounds include the alkali metal iodides, alkaline earth iodides, other inorganic water-soluble metal iodides, as well as organic or other sultabl compounds which may provide ionizable iodide ions on addition to the bath.

Examples o~ such iodide compounds include sodium iodide, potassium iodide, cesium iod~de~ llthium iodide, ammonium iodide, calcium iodide, magnesium iodide, nickel iodide, cobaltous iodide, etc. Materials which are converted to iodide in the cobalt-containing electroplating bath or during the electrodeposition process may also be employed. In particular;
iodine may be added (such as in the form of a solution in methanol) to the aqueous cobalt~containing bath composition to provide effective amounts o~ iodide anions by interaction with bath constituents such as cobaltous ion~ according to the invention herein. Organic compounds which provide ionizable iodide ions may also be employed, but the use of such compounds is generally not preferred unless the organic moiety contributes some added effect which may be desirable for a particular cobalt or cobalt-alloy electroplating process.
Any effective amount of iodide may be employed. By an effective amount as used herein is meant an amount of iodide which is sufficient to provide improved cobalt-containing electrodeposits from a cobalt-containing electroplating bath composition as compared to an identical cobalt-electroplating bath composition which is essentially free of iodide ions. In typical bath compositions which contain cobalt ions it has been found that at least about 0.1 g/l of iod~de (measured as iodide, I-, ion) has been found to be sufficient to obtain improved cobalt deposits and at least 0.1 g/l has been found to give excellent results. An iodide ion concentration of 0.1-5 g/l will generally be found sufficient. Higher amounts of iodide may be used, but in general the use of excessive amounts of iodide does not produce further enhancement of the cobalt-containing 3~ electrodeposit and may only serve to increase costs.

~o58~53 Typical aqueous nlckel-containing electroplating baths ~which may be used in combination with ef~ective amounts o~ cooperating additives) include the rollowing wherein all . concentrations are ~n grams per liter (g/l) unless otherwise indicated.
Salts to make up the bath are of the types generally used for nickel and cobalt plating i.e. the sul~ates and chlorides, usually combinations thereof. Ferrous iron may be added as Ferrous Sul~ate or Ferrous Chloride, or Ferrous Sulramate, preferably the sulfate which is easily available at low cost and good degree of purity (as FeSO4-7H20).

TABLE I
AQUEOUS NICKEL-CONTAINING ELECTROPLATING BAT~S
Component Minimum Maximum Preferred nickel sulfate 200 500 300 nickel chloride - ~ 30 80 45 ~errous sul~ate 5 80 40 boric acid 35 55 45 pH (electrometric) 3 5 4 A typical sul~amate-type nickel plating bath which may be used in practice o~ this invention may include the rollowing components:
.

¦ TABLE~ II
Component Minimum Maximum Preferred ¦ nickel sulfamate330 400 375 ¦ nickel chloride15 60 45 ¦ ferrous sulfamate ~ 60. 40 ¦ boric acid 35 55 45 sorbitol, mannitol, 10 ~0. 40 or dulcitol ¦ pH (electrometric) 3 5 4 ¦ A typical chloride-free sulfate~type nickel plating ¦ bath which may be used in practice of this invention may include l the following components:
¦ TABLE III
Component Minimum Maximum Preferred l nickel sulfate 300 i500 400 l ferrous sulfate 5 60 45 ¦ boric acid 35 55 45 sorbltol, mannitol,10 60 40 ¦ or dulcitol ¦ pH (electrometric~2.5 4 3-3.5 .
¦ A typical chloride-free sulfamate-type nickel plating ¦ bath which may be used in practice of this invention may include ¦ the following components:
¦ TA~LE IV
¦ Component Minimum Maximum Preferred ¦ nickel sulfamate 300 400 350 ¦ ferrous sulfamate 5 60 45 ¦ boric acid 35 55 45 ¦ sorbitol, mannitol,10 60 40 ¦ or dulcitol ¦ pH (electrometric)2.5 4 3-3.5 It will be apparent that the above bathæ may contain compounds in amounts falling outslde the preferred minimum and maximum set forth, but most satisfactory and economical operation may normally be effected when the compounds are present in the baths in the amounts indicated. A particular advantage o~ the chloride-~ree baths of Table III and IV, ~ , is that the deposits obtained may be substan~lally free o~ tensile stress ~nd may permit hlgh speed plating involvlng the use of high speed anodes.
The following is an aqueous cobalt-nickel-iron-containing electroplating bath in which the combination of e~fecti~e amounts o~ one or more cooperating additivés according to this invention will result in beneficial effects.
TABLE V
AQUEOUS COBALT-NICKEL-lRON-CONTAINING_ELECTROPLATING BATH
(All concentrations in g 1 unless otherwise noted Maximum Minimum Preferred . __ Cobalt-Nickel Alloy~~th NiSO4-7H20 400 200 300 SoS04 7H20 225 15 80 NiCl2~6H20 75 15 60 FeSO4O7H20 60 5 45 Sorbitol, Mannitol, or 60 10 40 Dulcitol _ 14 Typical cobalt-iron plating baths are the following:
TABLE VI
Minimum Maximum Pre~erred Watts (high sulfate type) cobalt sul~ate 200 500 300 cobalt chloride 45 150 120 ~errous sulfate 5 60 45 boric acid 15 60 45 sorbitol, mannitol or10 60 40 dulcitol 10. pH electrometric 3.'0 4.5 4,0.
TABLE VII
Minimum Maximum Pre~erred Hi~h Chloride Ty~e ~ _ , cobalt chloride 100 300. 200.
cobalt sulfate 100 300 200 ~errous sulfate 5 60 45 boric acid ~ 15 60. 30 sorbitol, mannitol or10 60. 40.
dulcitol ~S8~iS3 The pH of all of the ~oregoing illustrative aqueous iron-nickel-containing, cobalt-iron-containing and nickel-cobalt-iron-containing compositions may be maintained during plating at pH values of 2.0 to 4.5 and preferab~y from 3.0 to 3.5. During bath operation, the pH may normally tend to rlse and may be adjusted with acids such as hydrochloric acid or sulfuric acid~
etc.
Operating temperature ranges for the above baths may be about 30 to 70C. with tempera~ures within the range of 45 to 65 C. pre~erred.
Agitation of the above baths during plating may consist of solution pumping, moving cathode rod, air agltation or combinations thereof.
Anodes used in the above baths may consist of the particular single metals being plated at the cathode such as iron and nickel, for plating nickel-iron, cobalt and iron, ~or plating cobalt-iron, or nickel, cobalt, and iron, for plating nickel-cobalt-iron alloys. The anodes may consist of the separate metals involved suitably suspended in the bath as bars, strips or as small chunks in titanium baskets. In such cases the ratio of the separate metal anode areas is ad~usted to correspond to the particular cathode alloy composition desired.
For pla~ing binary or ternary alloys one may also use as anodes alloys o~ the metals involved in such a per cent weight ratio of the separate metals as to correspond to the percent weight ratio of the same metals in the cathode alloy deposits desired.
These two types o~ anode systems will generally result in a ~airly constant bath metal ion concentration for the respective 1~ 1058553 metals~ If with fixed metal ratio alloy anodes there does occur some bath metal ion imbalance, occasional adjustments may be made by adding the appropriate corrective concentration of the individual metal salts. All anodes or anode baskets are usually suitably covered with cloth or plastic bags of desired porosity to minimiæe introduction into the bath o~ metal particles, anode slime, etc. which may migrate to the cathode either mechanically or electrophoretically to give roughness in cathode deposits.
The following examples are submitted for the purpose of lllustration only and are not to be construed as limiting the scope of the invention in any way.
Hull Cell tests were run under conditions described as ~ollows and the deposits were examined along a line 2.54 cm from and parallel to the bottom edge of the Hull Cell panel.
A polished brass panel was scribed with a horizontal single pass of ?/O grit emery to give a band width of about 1 cm.
at a distance of about 2O5 cm. ~rom the bottom of the panel. A~te cleaning the panel, including the use o~ a thin cyanide copper strike to assure excellent physical and chemical cleanliness, it was plated in a 267 ml. Hull Cell, at a 2 ampere cell current for 10 minutes, at a temperature of 50~C. and using magnetic stirrlng.
A Watts Nickel bath was prepared having the following makeup composition:

nickel sulfate - 300 g/l nickel chloride - 60 g/l boric acid - 45 g/1 The bath was given a high pH nlckel carbonate treatment to preclpitate heavy metal impurities, treated with 6 grams per 3o liter of activated carbon and filtered after overnight digestion at 60C.

EXAMPLE I
_ 250 ml. Watts Nickel ll g/l Sodium Saccharinate 2.3 g/l Sodium Allyl Sulfonate 0.05 g/l Diethoxylated Butynediol 40 g/l FeSO4o7H20 (equivalent to 8.o g/l Fe~2) 10 g/l Sodium Tartrate Dihydrate pH ad~usted to 4.0 electrometric Thin, iridescent, non-uniform haæy deposit wikh poor ;~n leveling from O ~o about 1.8 asd-brilliant and well-leveled ~rom 1.8 asd ko high current density edge (about 12 asd). On adding 1 g/l Sodium Formaldehyde Bisulfite brilliant, well leveled deposit from O to 12 asd with excellent ductility and 1QW Gurrent density coverage. On lncreasing the FeSO407H20 content to 60 g/l an excellent deposit was st,ill obtained with no noticeable change in appearance or physical properties.
EXA`MPLE II
Same bath composition as ~or Example I except 10 g/l dl-Malic Acid as the hydroxy-carboxylate compound used~
Thin, uniformly hazy, poorly leveled deposit from O
to about 2.2 asd - iridescent, non-uniform, milky from 2.2 asd to about 5.0 asd- brilliant, well-levele~ ~rom 5 asd to high current density edge. On adding 1 g/l Sodium Formaldehyde Bisulfite brilliant, well leveled deposit from O to 12 asd. On increasing the FeSO4-7H20 content to 60 g/l a slightly hazy area about 1 cm. wide and 2.5 cm. long, eliptical in shape, appeared at the bottom low current density corner of the panel but the appearance and physical properties of the remainder of the deposit remained unchanged.

~585S3 EXAMPLE III
Same bath composition as for Example I except that 10 g/l Sodium Citrate Dihydrate was the hydroxy-carboxylate compound used.
Thin, very hazy, poorly leveled deposit between 0 and 3.0 asd - iridescent, non-uniform, milky ~rom 3.0 to about 4.5 asd - brilliant and well-leveled ~rom 4.5 asd to high current density edge. On adding 1 g/l Sodium Formaldehyde Bisulfite a brilliant, well-leveled, ductlle deposit from 0 to 12 asd wikh excellent low current density coverage. On increasing the FeSO4-7H2O content to 60 g/l, a small non-uni~orm, lridescent milky area in the lower high current density end o~ the panel and a slight haze from 0 to about 0.2 asd were obtained - remaind r of panel unchanged in appearanceO On increasing the Sodium Formaldehyde Bisulfite to 2 g/l the high current density defect was eliminated but the very low current density haze persisted -the remainder of the panel was unchanged in appearance.
EXQMPLE IV
~ Same bath composition as for Example I except that 10 g/l Sodium Glycolate was the hydroxy-carboxylate used.
Thin, hazy, poorly leveled deposit from 0 to about 2.2 asd ~ brilliant and well-leveled from 2.2 to 12 asd. On adding 1 g/l Sodium Formaldehyde Bisulfite a brilliant, well-leveledj ductile deposit from 0 to 12 asd w~th excellent low current density coverage. On increasing the FeSO4-7H2O to 60 g/l a thln hazy band from 0 to about 0.05 asd was obtained -the remainder o~ the panel unchanged in appearance.

EXAMPh~ V
Same bath composltion as for Example I except that 10 g/l Sodium Boroglucoheptonate was the hydroxy-carboxylate used Thin hazy deposit from 0 to 1.4 asd - non-uniformly dull with some iridescence from 1.4 to about 5.0 asd - brilliant well leveled from 5.0 asd to high current density edge. On adding 2 g/l of Erythorbic (Isoascorbic) Acld and read~usting pH to 4.0 thin, poorly leveled~ hazy deposit from 0 to about 1.1 asd - dull, iridescent from 1.1 to 4.0 asd, bright with fair levellng from 4.0 asd to high current density edge. On adding 2 g/l Sodlum Formaldehyde Bisul~ite bright deposit from 0 to 12 asd with only fair leveling.
''CO~ALT'-'IRON PLATING -'CO'ANODE USED
A Cobalt Watts type solution was prepared having the , following compositiont cobalt sulfate - 300 g/l cobalt''chloride - 60 g/l boric acid - 45 g~l A~ter make-up the bath was given a high pH Cobalt Carbonate-activated carbon purification ~reatment and filtered after digestion overnight at 60C.
EXAMPLE VI
250 ml. of above stock solution 40 ml/l of 70% by wt. Sorbitol solution 80 g/l ~eSO4-'7H20 ' pH adjusted to 3.6.

; ~058553 Deposit lustrous from O to about 2.0 asd - iridescent milky from about 2 asd to 2.5 asd - milky from 2.5 to 11 asd -non-uni~ormly dull from 11 to 12 asd. On adding ~
Saccharinate bare (no deposit~ from O to about 0.1 asd - lustrous from 0.1 asd to 2.4 asd - dull white from 2.4 asd to 3.0 asd -satiny milky from 3 asd to 12 asd and brittle. On adding ~urther 1 g/l KI (over a nickel strike) the deposit was generally milky from O to about 5.0 asd, and smutty, dull and badly pitted from 5 asd to high current density edge. On adding 2.3 g/l Sodium Allyl Sulfonate deposit lustrous from O to about 1.5 asd, and very dark, non-uniform and very brittle from 1.5 asd to high current density edge. The deposit was so poor tha~ a primary brightener was not added since from experience such a brightener, if anything, will make the deposit worse unless one can start with a ~airly uniformly hazy, glossy, ductile depositO
EXAMPLE ~II
250 ml. above stock solution 4 g/l Ascorbic Acid pH adjusted to 4.3 Lustrous deposit from O to about o.8 asd - dull gray, brittle from 0.8 asd to high current density edge. On adding ¦ 4 g/l Sodium Saccharinate the entire deposit dull with a dark brownish cast. On further adding 20 g/l FeSO4-7H20 the deposit bare along low current density edge, lustrous up to about 0.15 asd - smeary, off-color and covered with micro-mounds from 0.1~
asd to high current.density edge. On increasing the FeSO~-7H20 to 40 g/l the deposit glossy semi-bright from O to about 0.2 asd -non-uniform thin satiny wh~te up to about 3.0 asd - partially lustrous from 3 asd to hlgh current density edge.
Based on the previous two Examples the plating of a sound Co-Fe alloy did not appear promising until the following tests.
EXAMPLE VIII
250 ml. above stock solutlon 40 g/1 FeSO4-7H20 2 g~l Erythorblc Acid lQ 4 g/l Sodium Saccharinate 2.3 g/l Sodium Allyl Sulfonate pH adjusted to 4.0 Non-uniformly milky, brittle deposit from O to 12 asd.
On adding 2 g/l Sodium Formaldehyde Bisulfite bright, poorly leveled deposit from O to about 5.0 asd - yellowish to dark and very brittle from 5 asd to high current density edge. On adding 20 g/1 Sorbitol and readjusting pH to 4.0 deposit lustrous with scattered haze and ductile from O to about 8 asd dull gray, grainy, brittle from 8 asd to high current density edge. On . ~
further adding 50 mg/l Diethoxylated Butynediol deposit bright with poor leveling from O to about 1.8 asd - non-uniformly very milky, iridescent from 1.8 asd to high current density edge.
On further adding 1 g/l KI brilliant poorly leveled deposit from O to about 2 mm. from high current density edge - dull grainy 2 mm~ width band along high current density edge. On increasing the Cobalt Chloride content ~rom 60 to 120 g/l brilliant fairly well-leveled, ductile deposit from O to high current density edge. A satisf`actory bath composition to give a very good, commercially acceptable deposit was then:

3L~58553 Cobalt Sulfate 300 g/l Cobalt Chloride 120 g/l Boric Acid 45 g/l Sorbitol 20 g/l Erythorbic Acid 2 g/l Sodium Formaldehyde Bisulfitel g/l ` Potassium Iodide 1 g/l Sodium Saccharinate 4 g/l Sodium Allyl Sulfonate 2.3 g/l Ferrous Sulfate 40 g/l Diethoxylated Butynediol50 mg/l pH 4.0 It was evident ~rom the test sequence that Erythorbic Acid, Sodium Formaldehyde Bisulfite, Potasslum Iodide and Sorbitol synergistically interacted with 1, 2 and 2 auxiliary brighteners to give an excellent deposit~ increasing the Cobalt Chloride content lncreased the limiting current density. A~ter the addition of KI all the deposits o~ this Example were made over a thin nickel strlke.
EXAMPLE IX
A bath having the following composition was prepared and purified by activated carbon treatment.
cobalt chloride - 200 g/1 cobalt sulfate - 200 g/l boric acid - 30 g/l To 250 ml. of the above bath there were added the equivalents o~ the following:
Sorbitol 40 g/l FeSO4-7H20 40 g/l Sodium Saccharinate 4 g/1 Sodium Allyl Sulfonate 2.3 g/l Potassium Iodide 1 g/l pH adjusted to 4.0 The deposit was non uniformly very milky from 0 to about 3.5 asd and lustrous from 3.5 asd to the high current density edge. The leveling was poor. On adding 1 g/l Sodium :~58S~3 Formaldehyde Bisulfite the deposit was lustrous from O to 12 asd with poor leveling and a very slight rather uniform haze - the ductility was excellent. On further adding 50 mg/l Diethoxylated Butynediol a brilliant, ductile, ~airly well leveled deposit was obtained from O to 12 asd and the low current density co~erage was ~airly good. All the deposits of this Example were made over a thin nickel strike deposit.
EXAMPLE X
The bath of Example I was then sub~ected to a 4~1iter life test using conditions as follows:
Platlng cell - 5 liter rectangular cross-section tl3 cm x 15 cm~ made of Pyrex.~R~ n~
Solution volume - 4 liters to give a solution depth, in absence of anode, of about 20.5 cm.
Temperature - 60C. (maintained by immersing cell in a thermostatically controlled water bath).
Agitation -~moving cathode rod.
Anode - single bagged titanium basket containing - SD nickel squares.
- Cathode - brass strip (2.54 cm x 20.3 cm x 0.071 cm~
bu~fed and polished on one side and immersed to a depth of about 17.8 cm - horizontal bend 2054 cm from bottom and the next 2.54 cm bent to give an internal angle on the polished side of cathode of about 45 - poliæhed side facing anode at an approximate distance o~ 10.2 cm and scribed vertically in center with a 1 cm wide band of a s~ngle pass Or 2/0 grit emery paper scratches.

~ [I5~5S;~

Cell current 5.0 amperes.
Time - solution electrolyzed about 7 hours per day -occasional cathodes plated ~or 30 minutes to evaluate deposit leveling, uniformity, ductility, luster (overall and in low current density recessed area~.
Filtration - occasional batch.
Additions - the pH was periodically ad~usted when necessary with dilute sul~uric acid to within a range of 3.0 to 3.5 electrometric; periodic replenishment additions of khe primary brlghtener and the secondary auxiliary brightener were made to maintain deposit luster and leveling. The ferrous iron content of the bath was maintained with separate nickel and Armco iron anode systems in bagged tikanium baskets with occasional corrective additions o~ ferrous sulfate, based on analysis for ferrous iron, to mainkain the-nickel and ferrous iron cantents of the bath fairly constant.
Plating tesks were first run on the bath of Example I
also conkaining 0.125 g/l Sodium di-n-hexyl-sulfosuccinate and made up initially without Sodium Formaldehyde Bisulfite, us~ng electrolytic nickel squares as anode in a bagged titanium anode basket, adding iron as 40 g/l FeS04-7H20 and using air agitation at a temperature o~ 60C. The first two deposits showed a definite haze in the recess of the bent cathode and at the solutlon line and this was completely eliminated after addlng 1 g~l Sodium ~ormaldehyde Bisulfite to subsequently give brllliant, ductile, quite well leveled deposits overall. After several hundred ampere-hours o~ electrolysis, during which period suitable additive replenishments (mainly 1 brightener and FeSO4-7H20) were made to give a bright, leveled alloy containing about 35% Fe on the average, a ba~ic iron precipitate ~ormed to some extent on the anode bag, some of which also became suspended in the solution resulting in an "orange-peel" defect on "shelf"
areas. On adding 2 g/l Erythorbic Acid the basic ferric salt was reduced and solubilized and excellent performance was again attained.
The deposits had the following general character-istics:
Brightness - very good and easy to maintain.
Ductility - excellent.
Internal Stress - low tensile.
ZO Leveling - ~airly good.
Hydrogen Embrittlement by Chromium Plating - very low.
Pitting Tendency - very low.
Smoothness of Deposits - excellent.

~ 1058553 ~XAMPLE XI
Using the finally evolved bath composition of Example VIII a 4 liter life test was run on depositing a brilliant, leveled cobalt-iron alloy using essentially the conditions of Example X except that the anode metal was cobalt Optimumly using movlng cathode rod agitation to attain best deposit luster in extreme low cathode current density areas, bright, well-leveled, ductile cobalt-iron deposits having tenslle stress were obtained consistently. It was found, however, over an electroly-~0 s~s period o~ several hundred ampere-hours that the average cobalt content was about 94% while the average iron content was only about 6%. This relatively low iron content would not seem to make the decorative plating of bright, leveled cobalt-iron alloy economically attractive because of the preponderant alloy~
metal content would be o~ the relatively expensive cobalt. In contrast, in nickel-iron alloy plating substantially higher iron contents may be obtained, say, up to almost 50%, which together with the lower price for nickel than for cobalt makes nickel-iron alloy plating much more economically attractive for decorative commercial purposes. In cobalt-iron plating the metal cobalt acts as a metal considerably more noble than iron and thereby plates in preference to iron at the cathode even at relatively high bath iron metal contents. However applications may be found for the utilization of a high cobalt-low iron sound alloy deposit to take advantage of possibly special magnetic, metal-lurgical, physical etc. properties.

105~553 Although thls invent~on has been illustrated by reference to specific embodiments, modi~ications thereof which are clearly within the scope of the invention will be apparent to those skilled in the art.

Claims (25)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the preparation of an electrodeposit which contains iron and at least one metal selected from the group consist-ing of nickel and cobalt which comprises passing current from an anode to a cathode through an aqueous plating solution containing a ferrous compound and at least one member selected from the group con-sisting of cobalt compounds and nickel compounds providing cobalt and/or nickel ions for electrodepositing alloys of iron with cobalt and/or nickel and containing in combination an effective amount of:
(1) at least one member selected from the group of cooper-ating additives consisting of:
(a) primary brightener (b) secondary brightener (c) secondary auxiliary brightener (d) anti-pitting agent;
(2) an organic hydroxy-sulfonate compound of the formula:

wherein M is a cation having a valence of 1-2; k is an integer 1-2 corresponding to the valence of M; and R is hydrogen or a monovalent aliphatic group of 1-16 carbon atoms;

(3) a hydroxy-carboxylate complexing compound or a polyol complexing compound selected from the group consisting of mannitol, sor-bitol and dulcitol; and (4) an iodide of a bath compatible cation or a compound pro-viding an iodide anion when plating cobalt-containing alloys for a time period sufficient to form a sound metal electroplate upon said cathode sur-face.

2. The process of Claim 1 wherein said primary brightener is 1,4-di-.beta.-hydroxy ethoxy-2-butyne).

3. The process of Claim 1 wherein said primary brightener is 1,4-d1-.beta.-hydroxy propoxy-2-butyne).

4. The process of Claim 1 wherein said organic hydroxy-sulfonate compound is sodium formaldehyde bisulfite.

5. The process of Claim 1 wherein said hydroxy-carboxylate is sodium tartrate dihydrate.

6. The process of Claim 1 wherein said hydroxy-carboxylate com-pound is malic acid.

7. The process of Claim 1 wherein said hydroxy-carboxylate com-pound is sodium citrate dihydrate.

8. The process of Claim 1 wherein said hydroxy-carboxylate com-pound is sodium glycolate.

9. The process of Claim 1 wherein said hydroxy-carboxylate com-pound is sodium boroglucoheptonate.

10. A process for the preparation of a cobalt-iron electrodeposit which comprises passing current from an anode to a cathode through an aqueous plating solution containing in combination an effective amount of cobalt sul-fate, cobalt chloride, boric acid, sorbitol,erythorbic acid, sodium formal-dehyde bisulfite, potassium iodide, sodium saccharinate, sodium allyl sulfonate, ferrous sulfate, and diethoxylated butynediol for a time period sufficient to form a sound metal electroplate upon said cathode surface.

11. An aqueous plating solution containing at least one ferrous compound and at least one member selected from the group consisting of nickel compounds and cobalt compounds, providing ions for electrodepositing cobalt-iron alloy, nickel-iron alloy, or nickel-cobalt-iron alloy and containing in combination an effective amount of:
(1) at least one member selected from the group of cooperating additives consisting of:
(a) primary brightener (b) secondary brightener (c) secondary auxiliary brightener (d) anti-pitting agent;
(2) an organic hydroxy-sulfonate compound of the formula:

wherein M is a cation having a valence of 1-2; k is an integer 1-2 corresponding to the valence of M; and R is hydrogen or a monovalent aliphatic group of 1-16 carbon atoms;

(3) a hydroxy-carboxylate complexing compound or a polyol complexing compound selected from the group consisting of mannitol, sor-bitol and dulcitol; and (4) an iodide of a bath compatible cation or a compound pro-viding an iodide anion when the aqueous plating solution contains a cobalt compound.

12. The composition of Claim 11 wherein said primary brightener is 1,4-di-(.beta.-hydroxy ethoxy-2-butyne).

13. The composition of Claim 11 wherein said primary brightener is 1,4-di-.beta.-hydroxy propoxy-2-butyne).

14. The composition of Claim 11 wherein said organic hydroxy-sul-fonate compound is sodium formaldehyde bisulfite.

15. The composition of Claim 11 wherein said hydroxy-carboxylate is sodium tartrate dihydrate.

16. The composition of Claim 11 wherein said hydroxy-carboxylate compound is malic acid.

17. The composition of Claim 11 wherein said hydroxy-carboxylate compound is sodium citrate dihydrate.

18. The composition of Claim 11 wherein said hydroxy-carboxylate compound is sodium glycolate.

19. The composition of Claim 11 wherein said hydroxy-carboxylate compound is sodium boroglucoheptonate.

20. The composition as claimed in Claim 11 wherein said nickel compounds are nickel sulfate and nickel chloride.

21. The composition as claimed in Claim 11 wherein said nickel compounds are nickel sulfamate and nickel chloride.

22. The composition as claimed in Claim 11 wherein said cobalt compounds are cobalt sulfate and cobalt chloride.

23. The composition as claimed in Claim 11 wherein said cobalt compounds are cobalt sulfamate and cobalt chloride.

24. The composition as claimed in Claim 11 wherein said ferrous compound is ferrous sulfate or ferrous chloride.

25. An aqueous plating solution which contains cobalt sulfate, cobalt chloride, boric acid, sorbitol, erythorbic¦
acid, sodium formaldehyde bisulfite, potassium iodide, sodium saccharinate, sodium allyl sulfonate, ferrous sulfate, and diethoxylated butynediol.