Note: Descriptions are shown in the official language in which they were submitted.
~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:
-- 1 --
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
105B553
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~
CH2CH2CN
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
1058553
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).
1058553
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
1058553
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.
1058553
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:
.
1058553
¦ 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
1058553
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
H3BO3 50 37 45
FeSO4O7H20 60 5 45
Sorbitol, Mannitol, or 60 10 40
Dulcitol
_ 14
1058553
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.
- 17
1058553
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.
10585S3
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 -
1058553
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
1058553
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.
