close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2407490

код для вставки
2,407,489
Patented Sept. 10, 2946
tum-ran sures PATENT orrica
nnnc'raonaiggr‘gonorzmc
to E. I.
Allen G. ‘Gray, Rocky River, Ohio, asalgnor
Wilmington,
du Pont de Nemonrs & Company,
M, a corporation of Delaware
No Drawing. Application September 22, 1942,
Serial No. 459,288
14 Claims.
1
.
This invention relates to the electrodeposition _
of zinc, and more particularly to acid plating com
positions, baths, and processes for the electro'—''
deposition of zinc in the presence of an anthra
quinone sulfonate.
'
~
(01. 204-55) _
2
lesses for the production of dense, adherent, non
porous, and ductile electrodeposits oi.’ zinc which
are readily deposited in low current density areas.
A further object is to provide processes for elec
trodepositing zinc over a variety of current den
sities, including low current densities, on dl?l
Securing a good initial deposit in low current
density areas upon an object being electroplated ' ' cultly platable objects such as irregularly shaped
objects of cast or malleable iron. Further objects
is often a di?icult problem. This vdiillculty, com
will become apparent hereinafter.
monly referred to as lack of "covering power”
The foregoing and other objects of this inven
restricts the usefulness of many electroplating 10 tion
are accomplished by processes in which zinc
systems, since for satisfactory electroplating it
is electrodeposited in the presence or‘ an anthra
is important that the object plated be covered
quinone sulionate and are further accomplished
over its entire surface with a deposit of relative
by electrodepositing compositions and solutions
ly uniform thickness, and, with irregularly shaped
in
which an anthraquinone sulfonate is present.
objects, it is entirely unleaslble to distribute the
The processes and compositions of this inven
current so as to avoid low current density areas.
tion are characterized by their ability to e?ect
> Lack of covering power is an especially trouble
deposition of zinc from acid baths over a wide
range of densities. They are further character
some problem in electroplating such metals as
cast iron and malleable iron, and it has, for in
in that the deposits produced are dense, ad
stance, heretofore been considered impracticable 20 ized
herent,
and of relatively uniform thickness. The
to electroplate malleable or cast iron objects with
applicability of such deposits to corrosion pro
certain metals or in certain otherwise advanta
geous electroplating baths on account of this de
tection of base metals will be readily apparent.
Bene?ts are achieved according to the pres
?ciency.
The problem of securing adequate covering 25 ent invention with any acid-zinc plating baths,
that is, baths having a pH lower than about 7.
power at low' current densities is encountered at
Acid-zinc electroplating baths may contain as
least to some extent in all systems for the elec
the
principal electrolyte, for instance, zinc sul
trodeposition of platable metals, but the need for
a satisfactory answer to this problem has been
fate or zinc chloride as shown in the examples
Zinc is very resistant to corrosion, and accord
as zinc sulfamate, zinc acetate, and zinc formate.
particularly pressing in those systems where an 30 below or may contain any other salt of zinc which
is stable in acid solution and is su?lciently solu
important purpou of the electrodeposited metal
ble to give a substantial supply of zinc ions, such
is to protect the base metal against corrosion.
The baths may be acidic by reason of the pres
ingly with systems for the 'eleetrodeposition of
zinc it is extremely important to have good cover 35 ence therein of an acid zinc salt, such as zinc
ing power in all current density ranges;
7
Solutions for the electrodeposition of zinc may
be broadly classi?ed into two widely di?erent
categories, namely, acid-zinc baths, such as those
sulfate, or of other acid constituents such as‘
. aluminum sulfate or chloride or ammonium chlo
ride, or of both an acidic zinc salt and another
acidic constituent. The acidity need not be great;
is, the pH need not be extremely low, and
containing zinc sulfate, and cyanide-zinc baths, 40 that
may, for instance, desirably be in the range of
such as those containing zinc cyanide, as the elec
trolyte in each case. By means of suitable ad
dition agents cyanld -zinc baths have‘been im
proved in recent years so as to give bright,
I smooth
deposits in all practical current density ranges.
‘ For some purposes such mirror-like deposits are
from about 3.0 to 7.0. As already described, in
, such acid-'zinc systems, the di?iculty of getting
adequate coverage at low current densities is more
pronounced than in alkaline baths such as cya
nide-zlnc baths and the benefits to be derived
from the inclusion of an anthraquinone sulfonate
not required and for these uses the somewhat less
expensive acid-zinc baths would be suitable were‘
it not for the fact that di?lculty is encountered
in securing good coverage at low current densi 50
ties.
It is an object of the present invention to im
prove the covering power at low current densi
ties of acid-zinc electroplating systems; A fur
ther object is to provide compositions and proc 55
are enhanced.
.
According to this invention any anthraquinone
sulfonate may be employed in an electrodeposit
ing composition. There may be used, for instance,
monosulfonic acids, such as l-anthraquinone sul
fonic acid or 2-anthraquinone sulfonic acid, or
polysulfonic acids, such as 1,8-anthraquinone di
sulfonic acid or 2,7-anthraquinone disulfonic
2,407,4sc -
3
4
acid. The bath-soluble salts of the sulionic acids,
suchas sodium, potassium, or ammonium salts,
.
Example II
An acid-zinc plating bath was prepared as_de
or partial salts may suitably be used and because
of their excellent solubility. ease of preparation,
and ease or handling in dry form, the sodium
salts of thesulionic acids may be preferred. The
manner of adding the sulionlc acid is compara
tively unimportant, since whether the addition
scribed in the transactions. of the Electrochemi
' cal Society, vol. 80, p. 390, having the following
composition:
, agent is present asyan acid, or as a salt, or as
a partial salt, will depend upon the pH of the 10
bath. For purposes of this description where
reference is made to a sulfonate, it will be under
stood that this may be a salt or partial salt or
the free acid.
'
zine
Ammonium
sulfate (znsotvnlo)
chloride (N H401)
..............
.............. __
Aluminum sulfate (Al:(S0|)a.l8Hg0) ........ -.
sag. ‘Na
pH’ adjusted to 4.0.
_ Temperature 25° C. I
p
The amount 01 an anthraquinone sulfonate to 15
To this bath was added 0.2 g./l.'of l-anthra
include in an electroplating composition or bath
quinone sodium sulfonate. Smooth white ?ner
will vary, depending upon the plating system in
grained deposits were produced with excellent
volved, the metal being plated, the magnitude of
covering power.
Example III
effect desired, and other similar factors. "The
amount can best be determined by a few simple 20
An acid zinc plating bath was prepared as de
tests in the particular bath to be used. In gen
scribed in the transactions or the Electrochemi
eral it will be round that from about .05 to 5.0
cal Society, vol. 80, p._‘390, having the following
grams per liter of anthraquinone sulfonate will
composition:
.
be satisfactory.
'
Anthraquinone s'ulfonates may be used in acid 25
zinc electroplating baths‘ in combination with
other addition agents with which they are com
patible. As' such additional agents, there may
be used colloidal materials such as glue, wetting
Zinc sulfate (ZnS 04.7Hz0) .................. .
Aluminum chloride (AlCl;.6H;O) ........... __
Sodium sulfate (-NmSO.) .................... .
410
20
75
lbbe
agents such as alcohol sulfates or naphthalene 30
sulfonates, anti-pit agents and similar ancillary
materials. When a second addition agent is used,
the amount of the second agent may be. consider
ably varied but ordinarily it should be present
only in minor amount as, for instance, from about
.1 to 1.0 grams per liter.
When reference is made herein to electrodepo
sition of zinc it will be understood that the zinc
may be co-deposited with another metal or met
als to produce alloys. The invention is applica
ble,'for instance, in the co-electrodeposition of
zinc and nickel or cadmium.
The invention will be better understood by
reference to the following illustrative examples:
Example I
pH 3.5.
' '
Temperature 25° C.
To the bath was added 0.2 g./l. of i-anthra
quinone sodium sulfonate. As has been noted in
35 previous examples, the inclusion of the anthra
quinone sulfonate resulted in a decided increase
in the coverage at low current densities. Smooth,
dense white deposits were produced at current
densities up to about 100 amp./sq. it.
40
Example IV
An acid-zinc plating bath was Drepal‘ed‘as de
scribed in the transactions of the Electrochemi
-cal Society, vol. 80, p. 390, having the following
composition:
45
G./l.
An acid-zinc plating bath was prepared as de~
scribed in the transactions of the Electrochemi
Zinc sulfate (ZnSO?HgO) _________ -.
Sodium acetate (N aC=HaOa3Hr0 . . _
'cal Society, vol. 80, p. 390, having the following
50 Aluminum sulfate (Alg(SOi)|.l8HzO).
composition:
I G./l.
Qua:
sa's’
01.]881.
QM
pH 3.5.
Temperature 25° C.
OzJgal.
Zinc sulfate (Z11S04.7H:O) .................. ._
360
48
Ammonium chloride (N H401) ______________ __
Sodium acetate (N aC;H;0,.3H10) .......... ._
30
l5
4
2
To the bath was added 0.2 g./l. of l-anthra
Smooth, dense light
colored deposits were produced, with excellent
covering power.
55 quinone sodium sulfonate.
pH adjusted to 3.6.
Temperature 25° C.
' Example V
60
An acid zinc plating bath was prepared as de
To this bath was added 0.2 g./l. of l-anthra
scribed in the transactions of the Electrochemical
quinone sodium sulfonate to obtain a bath of
Society, vol. 50, p. 211 with the following compo
this invention. Copper test plates were electro
sition:
plated in this bath at various current densities.
It was found that complete coverage of the test 65
air. I Oz./ga.
plate with zinc was e?ected in oneminute at all
current densities including current densities as
Zinc chloride (ZnCl’) ....................... .136
low as 0.1 amp./sq. it. On the other hand sim
Ammonium chloride (NH4CI) ........ -_
-..
214
Aluminum
chloride
(AlClpGHzO)
...........
_.
1‘
20
ilar test plates electroplated in the solution be
fore the addition of l-anthraquinone sodium sul
pH adjusted to 4.0-.
ionate were not covered in one minute at current 7 ‘ Temperature
25° C.
densities below about 2 to 3 amps. per square foot,
indicating that the inclusion of the anthraqui
To the bath was added 0.2 g./l, of anthraqui
none sulfonate effected an improvement in the
none sodium sulfonate to secure a' bath of this
coverage at low current densities.
75 invention. Copper test plates were electroplated
0
I
.
2,407,489
5
6
make a solution of suitable concentration for elec
in this bath at various current densities. The
covering power obtained in this above chloride
bath was about equal to that obtained from the
sulfate type bath as described in Example ‘1. Fur.
troplating the anthraquinone sulfonate is present
in the solution at a concentration of from .05 to
5.0 grams per liter.
-
4. A zinc electrodepositing composition in dry
form,_comprising zinc chloride and an anthraqui
perior to the sulfate bath described in Example I.
none sulfonate, the proportions of anthraquinone
By ,use of the anthraquinone sulfonate in the
sulfonate and other constituents being such that
above bath complete coverage was obtained at
when the composition is dissolved in water to
current densities as low as 0.1 amp/sq. it. in one
make a solution of suitable concentration for elec
10
minute, whereas similar plates electroplated in
troplating the anthraquinone sulfonate is pres
the solution before the addition of the l-anthra
ent in the solution at a concentration of from
quinone sodium sulfonate were not covered under
0.5 to 5.0 grams per liter.
similar. conditions at current densities of 2 or 3
5. A zinc electrodepositing composition in dry
amp/sq. ft.
15 form, comprising zinc sulfamate and an anthra
Example VI
quinone sulfonate, the proportions of anthraqui
An acid-zinc plating bath of the chloride type
none sulfonate and other constituents being such
was prepared as described in the transactions of
that when the composition is dissolved in water
the Electrochemical Society, vol. 50, p. 211, with
to make a solution of suitable concentration for
the‘ following composition :
20 electroplating the anthraquinone sulfonate is
ther, the conductivity of this bath was much su
present in the solution at a concentration of from
0.5 to 5.0 grams per liter.
Zinc chloride (ZnCh) _______________________ _-
136
18
Sodium chloride (NaCl) __________ _-
_
234
31
Aluminum chloride (AlCh.6H;O) ......... ._
20
3
H 4.0
empe'rature 26° 0.
'
6; A zinc electrodepositing composition in dry
form, comprising a zinc compound and l-anthra
25 quinone sodium sulfonate, the proportions of an
thraquinone sulfonate and other constituents be
ing such that when the composition is dissolved
in water to make a solution of suitable concentra
Smooth, uniform, white dense zinc deposits
tion for electroplating the anthraquinone sul
were produced with excellent covering power at 30 fonate is present in the solution at a concentra
tion of from .05 to 5.0 grams per liter.
7. An aqueous zinc electrodepositing solution
tated solutions.
comprising a zinc compound and about from .05
By including an anthraquinone sulfonate and,
to 5.0 grams per liter of an anthraquinone sul
optionally, another addition agent in a dry mix
ture of zinc salts adapted to give an acid-zinc 35 fonate and having a pH lower than 7.0.
8. An aqueous zinc electrodepositing solution
bath upon dissolution in water, there is obtained
comprising a zinc sulfate and about from .05 tov "
a complete, balanced product which is ideally
5.0 grams per liter of an anthraquinone sulfonate
suited for use by the trade. Such a product may
and having a pH lower than 7.0.
readily‘be dissolved to make an acid-zinc plating
9. An aqueous zinc electrodepositing solution
bath without the necessity of individually meas 40
comprising a zinc chloride and about from .05 to
uring or proportioning the separate constituents.‘
5.0 grams per liter of an anthraquinone sulfonate
While certain illustrative compositions and,
and having a pH lower than 7.0.
processes have been shown, it will be understood
10. An aqueous zinc electrodepositingsolution
that the invention is not limited thereby but that
one skilled in the art, without departing from the 45 comprising a zinc sulfamate and about from .05
to 5.0 grams per liter of an anthraquinone sul
spirit of the invention, may. readily devise numers
fonate and having a pH lower than 7.0.
ous compositions and processes for the electro;
11. An aqueous zinc electrodepositing solution
deposition of zinc in the presence of an anthra
comprising a zinc compound and about from .05
quinone sulfonate.
50 to 5.0 grams per liter of I-anthraquinone sodium
I claim:
,
a
sulfonate ‘and having a pH lower than 7.0.
1. In a process for the electrodeposition of zinc,
12. In a process for the electrodeposition of
the step comprising effecting electrodeposition of
zinc. the step comprising e?ecting electrodeposi.
zinc from an aqueous acid-zinc electrodepositing
tion of zinc from an acid-zinc electrodepositing
solution in the presence of about from .05 to 5.0
grams per liter of l-anthraq‘iinone sodium sul 55 bath in the presence of about from 0.05 to 5.0
gramsper liter of an anthraquinone sulfonate.
fonate.
I
I
13,. In a. process for the electrodeposition of
2. A zinc electrodepositing composition in dry
zinc, the step comprising e?ecting electrodeposi
form, comprising a zinc compound and an an-~
tion of zinc from an acid-zinc electrodepositing
thraquinone sulfonate, the proportions of anthra
quinone sulfonate and other constituents being 60 bath comprising zinc sulfate as the principal elec
'trolyte, in the presence of about from 0.05 to 5.0
such that when .the composition is dissolved in
grams per liter of an anthraquinone sulfonate.
water to make a solution of suitable concentra
14. In a process for the electrodeposition of
tion for electroplating the .anthraquinone sul
’ current densities up to 100 amps/sq. ft. in unagi
fonate is present in the solution at a concentra
zinc,v the step comprising e?ecting electrodeposi
65 tion of zinc from an acid-zinc electrodepositing
bath comprising zincchloride as the principal '
3. A zinc electrodepositing composition in dry
form. comprising zinc sulfate and an anthraqui- ' electrolyte, in the presence of about from 0.05 to
" 5.0 grams per liter of an anthraquinone sulfonate.
none sulfonate, the proportions of anthraqui
tion of from .05 to 5.0'grams per liter. -
.
none sulfonate and other constituents being such
that when the composition is dissolved in water to 70
ALLEN a. can.
Документ
Категория
Без категории
Просмотров
0
Размер файла
444 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа