Note: Descriptions are shown in the official language in which they were submitted.
'' '~'' ~c~c~ u~_~___the Lnver~tion
ln the art of nickeL an~ ni.ckel alloy pl~tin~, a con-
siderable amount of energy is expended for hea~ing solu~ions, as
- most such plating processes operate wi~h op~iTnum bath ~emperatures
ranging from 140F to 165F. ~lost of the heating is done by
steam which requires fossil fuels, such as gas or oil.
In view of the potential shorta~e of fuels, this inyen-
tion has been directed toward the conservation of energy primarily
in the area of platlng bright deposits of nickel, nickel-cobalt
and nickel iron.
In ~he past, operating bright nickel formulations at
low tempera~ures has created such problems as'burned or nodular
' deposits in the high current densi~y regions and the inability
to build good deposit brightness and achieve leveling. In fact,
recent experiments have shown that the basic c'hemical formulations
normally employed in nickel plating, such as the Watts solution
containing approximately 300 grams/liter of nickel sulfate,
60 grams/liter of nickel chloride, and 6.ounces/gallon of boric
~ ' ~ ' ' , ,
. . . . ..
, . . . ..
~ .
. ~_ ' ' ' .
... , . , ., .. , , "~.~,.. . .
i
". . . . ...
.
.-. . . ,
,
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acicl, where the pll ranges rom ~bout 2.8 to about 4 5, wil~ not
give satisfactory bright deposits a~ temperature6 below about
120F, primarily because of severe burned and nodular deposi~s
that have a tendency to ~orm in the high curr~nt density regions.
It is to be noted that the prior art is replete with
literature concerning various methods and techniques from the
electrodeposition of nickel and nickel alloys. However,.the
literature does not provide any teaching which could be said ~o
even remotely suggest the instant invention as it is hereinaEter
described and claimed.
Summary of the Inven~ion
.
It has been found that with certain modifications of the
basic bath formulations entirely satisfactory deposits of bright
nickel and certaln alloys of nickel can be obtained while operat-
ing at plating bath temperatures ranging Erom about 85F to 115F
thus saving signiEicant amounts oE energy. Experiments have sho~m
that it is possible ~or a nickel or nickel alloy plating operation
to be started at temperatures as low as about 75F and that the
heat generated by the wattage expended during the course of plat-
20 ing is all that is required to m~intain the bath temperature at
a level where satisEactory deposits are obtained. It is recog-
nized that slightly more electrical energy is required when
`~ operating at lower temperatures, due to the decrease in conduc-
tivity in the solution, but this additional energy usage is
minute compared to the savings that are realized by the reduction
or elimination of the external heat requirements that are needed
: to maintain pri.or art nickel plaLin~ solutlons a~ the optimum
temperatures.
In connection with the practice oE the :instant invention,
it has been unexpectedly discovered that by reclucing the total
.. ~ .
~ , - .
35~)
nickel ion concentrat:i.on, as clescr:i.be(l h--reina~l-er in de~ail,
of the ylating bath and by the incorpora~ion therein of uni~lUe
combina~ions o~ organic addition agents (hereinaf~er discussed)
satisfactory deposits can be obtainecl while minlrni~ing the amount
of energy necessary to heat the plating bath to a fiuitable plating
temperature. The combination of lo~ nickel lon and addition
agents taught by the instant invention produces suf.~'icient
polarization of these high current density areas and thereby'
. alters the normal pattern of current distribution so that burned'
or nodular deposits are avoided. Extensive testing indicates
that the deposits of the invention a~e achieved without loss o
either cathode or anode efficiency as eompared to a Watts formu-
lation'bath.
Also, in the praetice of the present invention, it is
.15 noted that the reduction in the required amounts of nickel 'chemi-cals further reduces the cost of the operation of a nickel platlng
solution, as salt losses due to drag out and spillage are auto-
- matically recluced which, in turn, reduces waste treatment and
replacement costs proportionately.
20 ' ' In one aspect, the invention concerns a method of
obtaining a bright nickel base deposi-t, i.e., a deposit of nickel,
nickel-cobalt or nickel-iron on a substrate by controlling the
bath charaeteristics in order to minimiæe the amount of energy
necessary to heat the bath to a suitable pla-tin~ temperature.
More specifically the presen-t invention concerns a
method of obtalning a bright nickel base electrodeposit on a
substrate by passing electric current through an aqueous acidic
plating bath containing ions of the metal to be electrodeposited
while minimizing the amount oE energy necess~ry ~o heat the
plating bath to a suita'ble platin~ temperatllre which methocl
.
-- 3 --
~ 0~9~
comprises prov;ding an aqueous ac:idic plating ba~h having a pH
ranging from al~out 2.~ to about 5.0 (usuall~ stabili~ed by means of
a buffering agent, such as boric acid) which conLains fro~ about
25 to about 60 ~/1 of nickel ions, an efEective amount o~ '
chloride ions to cause satisfac~ory anode corrosion during the
formation of ~he electrodeposit, an efective amount o~ at least
one bath soluble primary 'brightener of the first class containing
a sulfo-oxygen group, and an effective amount of at least.one
bath soluble secondary brightener (as described herein), and main-.
taining the platlng bath at a temperature rangln~, from about
85F to about 115F whlle passing sufficient.electric current
through said bath to cause the desired metal ta be deposited on
-the substrate.
' . In the foregolng practlce of the lnventlon, the plating
15 bath contains from about 25 to about 60 g/l of the metal lons to .
be plated.. Accordlngly, when lt is desired to obtain a nlckel-
cobalt deposlt, an approprlate amount of the nickel lons are
- replaced wlth cobalt ions with the cobalt ions being present ln
an amount ranging from about a trace amount to lS g/l. Likewlse,
.when lt is deslred to obtain a nickel-iron deposit, an appropr,iate
amount of the nlckel ions are replaced with ferrous ions with the
ferrous ions being present in an amount ranglng from a trace
amount to about 15 g/l. Obviously, when ferrous lons are included
'in the bath an effective amount of chelating'agent must be used to
prevent the ferrous ions from precipitating.
. In connection with the above description oE the practlce
of the subject lnventlon lt should be noted that the term "nickel
base" ls intended to include nic'kel, nickel-coba'lt al'loys and
nlckel-lron alloys.
'~ ' 30 In addition, the present invent:ion relates to novel
.
. .
~;9 ~ S O
platiny, batlls WtliCh are utill~ed i.n connec~ion with the various
me~hods gene~ally discussed above.
Description of the Pre:~erred
Embodiments of the -rnvention - ''
.
As before noted, a~tempts to o~erate conventional Watts
type bright plating 'baths at low, energy saving temperatures have
' 5 been unsuccessful due in the main to the ~orma~ion of nodular
deposits and the inability to build good deposit brightness-and
achieve levelin~. In an attempt to overcome these problems it
has been unexpectedly discovered that bright, level dèposits of
nickel and nickel alloys can be obtained while operating at low,
energy saving temperatures if (1) the p~l of the bath is'maintained
in the range oE from about 2.8 to about 5.0 (usually by means of
a buffering agent such as boric acid), (2) the concentration
of-the metal ion to be plated is in the range of from about 25
to about 60 g/l, (3) the bath temperature is regulated so as to
15-- range from about 85 to about 115F, (4) an effective amount of
chloride ion is present to cause satisfactory corrosion of
the anode during plating, (5) a primary brightener of the first
class is utilized'to obtain a fine grain deposit, and (6) a
secondary brightener (of the described type) is utilized to
obtain a fully bright and ductile deposit.
~- ' By utilizing the forego'in~ technique, a deposit is
obtained which has leveling and.brightne~s properties which are
equivalent to those obtained from conventional high temperature
bright nickel baths.
The primary addition agents or bri~,hteners of the first
class employed in the practice oE this invent-ion include the aryl.
and a'lkyl sulfo-oxygen compounds, such clS sulfonic aclds and
their metal salts, sulfoxides, sulEonamides, suL~onimides, and
sulfones Prillcipa'lly, these compounds are used to obtain a fine
~' : ,, ~ '' ', .
. . , . :
y~
101~385~
~rain deposit. Since such co~npourlds a~e well known ~o those
skilled in ~he art they wil1 I~O~ be discussed herein in.~urther
detail.
Speci~ic compounds which have been ~ound to be especially
efective ~or this purpose are set ~orth in ~he following Table I.
The concentrations of these materials and combinations thereof
will vary widely, but generally the total concentration thereof
in the bath ranges from abou~ 0.1 to about 30.0 g/-L.
Table 1
Sodium Benzene Sulfonate
Sodium Meta-benzene Disulfonate
Benzene ~ulfonamide
p-Toluene Sul-~onamide
Sodium p-Toluene Sulfonate
Naphthalene Sulfonate
2,7-Naphthalene Dlsulfonate
1,5-Naphthalene Disulfonate
Sodium Naphthalene Trisulfonate
o-Sulfobenzoic Imide (saccharin)
.` 20 Sodium Vinyl Sulfonate
Sodium Al~yl Sul~onate
~ Sodium 2-Butene-1,4-Diol-2-Sulfonic Acid
: Sodium Butane-].,4-Diol-2,3-DisulEonate
. Sodium Thiophene Sulfonate
2-5 Sodium Styrene Sulfonate
Pyridine-.3-Sulfonic Acid
Dibenzene Sul-fonamide
Not all known secondary brightening agents can be
~ employed with the compounds of Table I to give a full bright
....... ... ... .30 deposit in the practice of the instant invention. For exam~le,
such well-known materials as triphenylmethane dyes, derivatives
of pyridine and the like generally give a deposit that is defi-
- cient in the degree of brightness, leveling and ductility. That
is, deposits so obtained do not exhibit physical characteristics
which are necessary for a commercially acceptable deposit.
Secondary brighteners that give ~he desired degree of
brightness, leveling and dwcti]ity when used in combination with
primary addition agents in the practice oE the. present ;.nvention
. , .
. . - 6 -
.
35~
are the lo~er molecular weigh~ ace~ylenic alcohols (rnore speci-
fically propargyl and bu~ne diol) and ~heir epo~ide adducts,
their sulfona~ed adcluc~s, and their alkyl ether sul~onic acid.
~erivatives. The epoxide adducts are col~lmon'Ly formed,by condens-
, 5 ing the appropriate acetylenic alcohol with alkylene oxides, such
- as ethyiene oxide, propylene oxide and epichlorohydrin. Addition'
agents or bri~hteners containing both tlle acetylenic linkage and'
the sulfonic acid group are commonly preparecl,b~ reacting the.
' appropriate acetylenic alcohol wi~h cer~ain alkane sul'tones ,(such
as propane sultone), or by condensing the appropriate acetylenic.
alcohol with a halogen-containing epoxide (such as epichlorohydrin)
followed by replacement of the halogen atom with a sulfonate-group.
' . The generic formula for the secondary brightener used
`: in the practice of the present invention is as follows:
' 15 , , RlC--ccH2OR2
~ wherein Rl is selected from the group consisting oE H, CH2OH,
CH2OR2; R2 is'selected from the group consistin~, of H, (CH2CH2O)nH,
(CH2CH(OH)CH2)nl~, (C~12)mS03M, (C~12CH(O~)CH2)nS03M,
(CH2CH ? (CH2CH(OH)CH2)SO3M, and (CH2CH2O)n(CH2)m 3 ,
. 20 an integer from 1 to 10; m is an integer rom 1 to 4; and M is~'
selected from the group consisting oE hydro~en, ammonium, alkali
, metal, nickel and cobalt.
'Speciic examples of these materials are set forth ln the
. following Table II:
, . .
Table II ' '
(See next pa~e).
- 7
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o ~
C.) O C`J r i C~ a~ r~ o
O O O
o o o ,~ o o o o c~l ~
O O O C O O O O O O '
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p~1 . ' .
~ : ~O-- ~ r~ r~ o U~ C~ C~l C~l Lr~ U
E~ O O G ~J O O O O ,~
¢ bl . ~ . .
K~
E~
7~ ~1 c~l ~ c~l .
o o o ,~
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Z¢ o o o C o o ~ C O O'
O ~
~ o O o C' C o o C~' C C
.
5~ ,,
O O'
C~l X Cl~ ~
$ ~') 0 ~`I O
~, ~ ~ X X
C~ X
$ ~'`1 o~ X
O C~
$ ~ O ~) O
O O~ ~C I _~ $~1
O X V~
~ ' C` ~'.0 t~ C`l O I I I C~
: `-- H E-~ X $ ~ ~ ~ ~ $ C~1ll `~ 1
- -. ~ C 7 ~ OC~ ~ C~
C` C`l ~ ~`J C`J, ~ C`l C~l C`l
$ $ ~ ~ $
' E~ $ ~ O ~ c~ ~
. C,/~ O O O O O .~ C`l O ~) O
4, C~ ' 111~4
~. ~ X X X ~ X
C~ C`C` ~ C`l C`l ~
O O OO U) O
$ ~ X ~ ~ X ~ X~C ~) ,I
~; $
O
~ri
' ' ' C', .4 ~ O
~,p, ~, ~Ll . I I
Fl o o ~) ,~ C~, ,
P- ~ h. ~ tJ h P.
,~ o P.~ ~ ~ o ~ ~ a
o h ^ o ~ ,~v ,~ h ,~ X X F
,~ oo o p~ o o o h
O ~ P.~r~ ~r~r~ ~ri~4~ JJ,
X ~ ~: ~ o ~ ~
o ^~^ o Io l o I ~ ~P
¢ ~ ~ ~ h t~ 1~ h ;~
. ~' X r-l - 'Cl ^ ~, ~ O I C~l
h o o ~
~ F ~F o~. I,s~ I ,~ I ~ ~
~,r, ~ o ~ ~ h
P~ ~P.~ ~ c~ 1 X
O~ ~1 o oo ~ ~ ~-~ O
P ~ h ~h P. -)I rJ I 3
~.~.O ~ o ~~,r. v~ r ~ o
:=1 h ~ I U I ~ I h I ~rl I ~rl I ~~ ^ h
~ P~ $ ~ , c~ l ~c~
- O . . .. . . . . . ~ O
~ ,~ c~ oo a~ r-~
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To ~la~e, experimen~al da~l has indicated that in connec-
t:ion Witil the practice of the subject in-vention i~ is preferred
to employ the secondary brightener in total concentra~on ranging
froM about O.OOL to about 3.0 g/l.
In the evaluation of the nickel and nickel alloys
deposited in accordance with che teachings of the instant inven-'
tion, the op~imum bath temperature ranges from about 85'~o 115F.
At such te~peratures, the preferred range for nickel'metal ions is
~; u~ from about 25 to about 60 g/l (with cobalt or iron ion being
present as described herein). In addition, :Erom a'bout 5 g/l to
CR ~ about 50 g/l of chloride ions should be present, preEerably ' '~
obtained from nickel chloride, in order to ensure satisfactory
corrosion of the nickel metal anode and increase the conductivity
oE the solution. Any balance of nickel ion being made up either
15 '~ . as nickel sulfate, nickel sulfamate, nickel fluoborate, or other
~ . suitable nickel-containing compounds
The p~l of the plating solution can be varied over a
. . .
range of from about 2.8 to about 5.0, but optimum leveling and
brightness is obtained in the range of about 3.6 to about 4.8.'
For best results, the bath of the present invention should also:`~
'include boric acid as a buffering agentj with the preferred amount
being àbout 60 g/l. However, it should be noted that any amount
of buffering agent ranging from about 35 g/l (grams per liter) to
saturation results in satisfactory system perormance, provided
the pH of the bath is maintained within the be:Eore specified
limits. Wetting agents can also be used in order to guard against
- the possibility of pitted cleposlts from hydrogen evolution at
the cathode surface or :oreign organic contaminat:ion o:E the bath.
In all nicke:L plating, some form of agitation or solution move-
ment is preferably employed and it has been Eouncl thclt the standard
method o air agitat:ion of the soL-l~ion, or continuous movement of
the cathode, is necessary.
.- -- 8
_, ._~ ................. . = = ................. ._.
:. .
In order ~o evaluate the presen~ inven~ion, ~he nickel
solutions were put in 1000 ml air-agitated'~lull Cells, employing
electrolytic nickel as the anode material and 3 1/~" x 5", ~7P-3'0
brass or polished steel test panels as the cathode. In theSe
cells, the 40 angle of the cathode gives a current density
ranging from 1 to 200 ASF when the applied current to the panel
is 5 amperes. Specific examples of some preferred formulations
used in the prac~ice of the invention are se~ forth in the
following examples.
EXAMPLE 1
'' NiS04 6~l2 '75 grams/liter (Ni apPr.ox. 16.5 g/l)
NiC12 6H2O 112 grams/liter (Ni approx. 26.5 g/l)
Boric Acid 52 grams/liter '
pH Range 3.8 to 4.2
-15 Temperature range100F. to 110F.
- Saccharin. 3.2 grams/liter
Sodium Benzene Suifonate2.0 grams/liter
Sodium Allyl'Sulfonate2 0 grams/liter
Sodium 2-Ethyl Hexyl Sulfonate 0.1 grams/liter
Optimum concentrations of the various compounds set forth in Table II.
The deposits from these solutions were fully bright at all
current densities and had good'ductility and leveling properties.
It was found that the leveling and brightness qualities
; could be increased to some degree by employing certain combina-
tions of the acetylenic compounds of Table II The best of such
combin.ations were primarily those that ernployed the acetylenic
sulf~onates with an acetylenic alcohol or epoxide adduct ~hereof.
Specific examples of plating baths ~imilar to those
' described in '~xample 'L which employecl at 'least two secondary
brighteners are described below.
.
~ g _
/i '~ ~
~o~9~
liXAMPL,E II
When 0.0~ g/l o:E compound 7 from Table II (Bis-B-
hydroxyethyl ether-2-butyn-1,4-diol) was used wi~h 0.05 g/l of
compound 10 of Table II (1~4-Dl(~ -hydroxy-A-sulfonic propo~y)-2-
5' butyne), a deposit was obtained which was full-bright, leveled
and ductile from 0.5 to 200 ASF (amps per square :~oot) and with no
burning on the HCD (high current denslty) edge. 'The leveling in
the LCD (low current density) region (0.5 to 40 AS~) was better
than when the compounds were used by themselves, as in Example I.
EXAMPLE III
' ' When 0.02 g/l of compound 2 from Table II (hydroxy-ethyl,
propynl ether) was used with 0.025 g/l of compound 9 cf Table II
(l-y-Sulfopropoxy-2-butyn-~-ol), a deposit was obtained which was
' full-bright, leveled and ductile from 0.5 to 200 ASE and with no
burning on the HCD edge. The leveling in the LCD ~egion (0.5 to
- 40 ASF) was better than when ~the compounds were used'by themselves,
as in Example I. The results were comparable to those of '
Example II.
' EXAMPLE IV
. When 0.01 ~/1 of compound 1 from Table Il (Prop'argyl'~
alcohol) was used with 0.025 g/l of compound 9 o Table II
ulfopropoxy-2-butyn-4-ol), a deposit was obtained which
was full-bright and comparable to Examples II and III in all
respects.
EXAMPLE V
When 0.05 g/l of compound 8 from Table II (Bis-~
-~ hydroxpropyl ether-2-butyn-1,4-diol) was used with 0.025 g/l of
compound 9 o~ Table II (l-Y-SulEopropoxy-%-~utyn-~-ol), a deposit
was obtained which was full-bright and equivcilent to the previous
examples.
- - 10 -
~ ' ~
~6 ~
In colmec~ion wi~h the practice of the invent:ion, lt has
been discovered that cobal~ or iron (toge~her ~ith a sui~able
chelating agent) can be subs~ituted for up to about 25% of the
nickel lon. Such alloy deposi~s are bright and duc~ile and
commercially acceptable.
The substitution of cobalt ion for a portion or the
nickel metal ion was shown to be possible, and the following
example describes a method for producing an alloy deposit contain-
ing approximately 40% cobalt and 60% nickel which is ful.ly bright
with good leveling and ductility properties.
EXAMPLE VI
4 2 33.0 grams/liter
CoS04 ~H2O 32.0 grams/liter
NiC12 6H2o 75.0 grams/liter
15 . Boric Acid . 45.0 grams/liter
- pH range 3.8 to 4 2
~~Temperature range . . 100 to I10F.
Saccharin 3 2 grams/liter
2,7-Naphthalene Disulfonate .4.0 grams/liter
20. So~ium Allyl Sulfonate 2.0 grams/liter
Bis-Hydroxyethylether-2-
butyne-1,4.-diol: 0.04 grams/liter
` - 1,4-di(~ -hydroxy-~ -sulfonic
~- propoxy)-2-butyne: 0.06 grams/liter
It has also been found that iron, as ferrous sulfate or
: ferrous chloride, may be substituted for a portion of the nlckel
ion to give a nickel-iron alloy deposit that contains 20 - 30%
iron, and 70 - 80% nickel, depending upon the ratio of nickel ion
to iron ion in the solution. I:lowever, :in addition to the pre-
` viously described additives, it is nece~sary that a suitable
`- ` chelating agent be employed in order to keep the iron in a
,
_ 1'1 _
,,
10~;~8SV
solubilizecl for~ plcal chela~:i.n~ ~Ig,erl~s i.nc'lutle such rnaterials
as ~he alkall (~r nickel metal salts of cit'ric, ascorbic or
gluconic aci~s.
The ~ol'Lowing example gave a brlght, duc~ile and level'
alloy deposit that analyzed as 13.4% lron, with the balance nickel.
EXAMPLE VII
4 2 llZ grams/liter
6ll2o 60 grams/liter
.. FeS04 7H20 20 grams/llter: '
Sodium Gluconate 22 grams/liter
Boric Acid 45 grams/liter -~
p~ range 3.5 to 3.8 -
Temperature 100F.
Saccharin 3.0 grams/li.-ter
' 15 Monobenzene Sulfonate 2.5 grams/liter
._ Sodium Allyl Sulfonate 2.0 gramsjliter
Bis I-lydroxyethylether-2- .
' ' butyne-1,4-diol 0.04 grams/liter
' '1,4-di(~ -hydraxy- ~-sulfonic
- propoxy)-2-butyne 0.06 grams/liter
Whi]e there have been described herein what are, at
present, considered to be the preferred embodiments of the inven-
.. tion, 'it will be obvious to those skilled in the art that various
changes and modi~ications may be made therein without departing
from the spirit and scope of the invention as hereinafter claimed.
.
,~ ' "
., ,
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