US3264200A

US3264200A - Electrodeposition of nickel

Info

Publication number: US3264200A
Application number: US338026A
Authority: US
Inventors: Richard J Clauss; Brown Henry
Original assignee: Udylite Corp
Current assignee: OMI International Corp; Udylite Corp
Priority date: 1964-01-16
Filing date: 1964-01-16
Publication date: 1966-08-02
Anticipated expiration: 1983-08-02
Also published as: GB1066663A; FR1420336A; DE1248414B

Description

United States Patent 3,264,200 ELECTRODEPOSITION 0F NICKEL Richard J. Clauss, Allen Park, and Henry Brown, Huntington Woods, Mich., assignors to The Udylite Corporation, Warren, Mich, a corporation of Delaware No Drawing. Filed Jan. 16, 1964, Ser. No. 338,026 8 Claims. (Cl. 204-49) This invention relates to the electrodeposition of nickel and in particular to the plating of ductile semi-bright nickel from aqueous acidic nickel electroplating solutions.

It is well-known in the art that certain aryl sulfonic acids and sulfonamides such as benzene sulfonic acid, naphthalene sulfonic acid, and benzene sulfonamide cause brightening in the nickel deposit obtained from acidic nickel solutions. These aryl sulfon compounds are generally used in conjunction with other types of addition agents such as active unsaturated compounds to obtain fully brilliant bright nickel deposits.

The essential feature which has characterized all of the previous aryl sulfon compounds used in nickel electroplating solutions, whether used alone or in combinations, has been the introduction of appreciable amounts of sulfur into the nickel deposit as nickel sulfide.

This invention is based upon the discovery that one particular aryl sulfon compound, metasulfobenzoic acid,

COOH

may be added to aqueous, acidic nickel solutions in appreciable concentration without introducing more than a very slight trace of sulfur into the nickel deposit. With the use of this compound, the concentration of sulfur in the nickel deposit usually is about 0.005% which is of the order of to A the concentration which arises from the use, in similar concentrations, of other aryl sulfon type compounds such as benzene mono-, and di-sulfonic acids, benzene or toluene sulfonamide, naphthalene mono-, diand tri-sulfonic acids, o-benzoyl sulfimide, and one of its possible hydrolytic products, ortho sulfobenzoic acid.

Metasulfobenzoic acid is unique among aryl sulfon compounds from the standpoint of introducing a minimum of sulfide sulfur into the nickel plate even at concentrations of 1 gram/liter and higher, and yet this compound is capable of markedly reducing the internal tensile stress of nickel deposits especially those obtained from Watts type and sulfamate type of acidic nickel electroplating baths.

While it is true that by using very low concentrations, such as 0.05 to 0.1 gram/liter, of the usual aryl sulfon compounds such as benzene sulfonic acid, o-benzoyl sulfimide, and the other aryl sulfon compounds mentioned above, it is possible to reduce the tensile stress of nickel deposits, and not obtain much greater than about 0.01% sulfur in the plate, nevertheless, a slight excess of these aryl sulfon compounds will start a very perceptible increase in the sulfur content of th nickel plate, and thus the control and maintenance of a consistent very low sulfur content of the nickel deposit is quite difiicult and not of the highest reliability.

When the meta sulfobenzoic acid is introduced into an acidi nickel solution such as the Watts bath, there is no appreciable effect on the appearance of the deposit which remains dull gray. There is, however, a very definite beneficial effect on the reduction of the tensile stress. On the other hand, the widely used aryl sulfon compounds while reducing the internal tensile stress of th nickel deposits also contribute very appreciable amounts of sulfide sulfur (over 0.01%) to the nickel plate at the same time they confer luster and grain refinement.

It was found that if the meta sulfobenzoic acid is added to semi-bright sulfur-free nickel baths, such as Watts baths containing small concentrations of chloral hydrate or formaldehyde, the plate stays semi bright and there is very little increase in sulfur content of the nickel plate, yet the tensile stress is very markedly reduced. Also the use of metal sulfobenzoic acid conjunctively with such compounds as the afore-mentioned aldehydes permits the operation of commercial semi-bright electroplating solutions with wide tolerance to variations of solution temperature and composition. For instance, a Watts type nickel solution which contains 3 grams/liter of the meta sulfobenzoic acid and 150 mg./l. of chloral hydrate may be operated at 150 F. while producing highly ductile semi-bright nickel deposits. In the absence of the sulfobenzoic acid, a gray, grainy deposit is obtained with poor ductility of the nickel deposit at this temperature. This is achieved without introducing more than about 0.005 sulfur. Without the metasulfobenzoic acid present, the temperature of the bath must be reduced to around F. in order to obtain ductile plate.

The use of nickel deposits with a minimum of sulfide sulfur is important in decorative protective applications of nickel-chromium deposits. For instance, the use of two layers of nickel, the first one substantially sulfur-free and constituting at least 50% of the total nickel deposit, and the second containing appreciable amounts of sulfur, followed by chromium plate markedly increases the corrosion resistance of the composite compared to a single layer of bright nickel of equal or double the total thickness overlaid with the same chromium deposit. The first nickel coating of such a double or duplex nickel system must be sulfur-free or substantially lower in sulfur content compared to the subsequent bright nickel which is plated upon it.

Nickel electrodeposits or electroforms used in engineering applications are often of greater thicknesses than thos used in decorative applications. These deposits must have excellent physical properties such as high ductility and low tensile stress. In some engineering applications, it is desirable that the deposits be of a very high degree of purity, and especially that the sulfide sulfur content is low.

The metal sulfobenzoic acid in a nickel sulfamate plating solution, for instance, changes the stress from a tensile to a slight compressive stress. Under the plating conditions necessary to do this, the sulfur content of the deposit was only 0.003%.

Meta sulfobenzoic acid is effective with either fast agitation such as air, or with slower mechanical agitation of the cathode. The optimum concentration ranges from 0.1 to 10 grams/liter. This compound can be used most effectively in nickel solutions such as Watts nickel baths, fluoborate and sulfamate baths and mixtures of these various acidic baths. Boric acid is the preferred buffer, though acetic, succinic, or citric acids can be used, though they are best used in conjunction with boric acid.

The best pH range is from about 2.8 to about 4.5. The temperature of the solution may be from. room to about 180 F. although it is generally preferred to maintain it from 120 F. to F.

When no air agitation is used, it is preferable to us a suitable wetting agent such as sodium octyl or lauryl sulfate or octyl sulfonic acid to prevent gas pitting. With air agitation, it is usually not necessary to use a wetting agent, but one which does not cause over-foaming, such as sodium-2 ethylhexyl sulfate may be used.

The metasulfobenzoic acid not only cooperates with low concentrations of formaldehyde, chloral hydrate and bromal in making possible semi-bright nickel of improved ductility and minimum tensile stress when the bath temperatures are raised :above the usual optimum temperatures, it also cooperates, though not as strikingly, with the following unsaturated compounds: dimethyl fumarate, trimethyl aconitate, coumarin, 3-chloro coumarin, 1,4 di(fl-hydroxyethoxy)butyne 2. In all these cases semi-bright nickel plate of excellent ductility and of very lowstress and very low sulfur content is obtained from Watts, sulfamate, kuoborate, bromide, and low all chloride (100 grams :per liter NiCl .6H O) baths. Also, improvements are obtained if the unsaturated compounds are sufonic acids of the type of HOCH -CEC-CH OC H SO H, or the reaction product of sodium sulfite with r BIC H OC H OCH CECCH OC H OC H Br (or their chloro instead of the bromo derivatives) as detailed in United States Patent 2,841,602, issued July 1, 1958, under Method 4, col. 3. There is always the possibility that the sulfite group adds to the triple bond and leaves a vinyl sulfonic type derivative (a sulfonic group attached to the unsaturated bond) whichal-so functions very effectively.

The metasulfobenzoic acid, by way of illustration, may be used in the bath formulations shown below to give lustrous, ductile, very low stressed semi-bright nickel deposits which contain less than 0.01% sulfur. It is preferred to use the compound as the free acid or the nickel salt.

Example I Concentration, grams/liter NiSO .6H O 200-300 NiCl .6H O 15-50 H BO 30-50 Meta sulfobenzoic acid 0.2- Chloral hydrate 0.03-0.2 Formaldehyde 0.01-0.1

Example II NiSO .6H O 200-300 NiCl .6H O -50 H BO 30-50 Meta sulfobenzoic acid 0.5-5 Chloral hydrate 0.04-0.2 1,4-di(fl-hydroxyethoxy)butyne-Z 0.01-0.1

Example III Ni(SO NH (nickel sul-famate) 250-500 NiCl .6H O 0-30 H BO 30-50 Meta sulfobenzoic acid 0.5-5

Example IV NiSO .6H O 200-300 NiCl .6H O 30-60 H BO 30-50 Meta sulfobenzoic acid 0.5-5

Coumarin and/ or 3-chlorocoumarin and/or dimethyl fumarate 0.050.4

I Example V NiSO .6H- O or Ni(SO NH 250-400 NiCl .6H O 0-30 H BO 30-50 Succinic acid 0 5 Meta sulfobenzoic acid 0.3-7 Form-aldehyde 0.01-0.15 Chloral hydrate 0.02-0.25

(nickel or sodium salt) 0.01-0.15

Example VI Ni(SO NH (nickel sulfamate) 250-500 NiBr 0-30 added to the baths as a nickel salt.

H BO 3040 Meta sulfobenzoic acid 0.5-5

In the above cited siX examples, the preferred pH range is 2.8-4.5 and bath temperature 140-150 F. The cathode current densities may be an average of 40 to 60 amps/sq. ft. with air agitation, and much higher with fast mechanical solution agitation.

The metasulfobenzoic acid is generally prepared by the sulfon-ation of benzoyl chloride or benzoic acid with chlorosulfonic acid. The metasulfobenzoic acid is usually neutralized with nickel hydroxide or nickel carbonate, and It, however, can be added as the free acid, or as sodium or magnesium, etc., salt. If too high a concentration of the free acid is added to the nickel bath at one time the pH of the bath may drop below pH=1 and therefore the nickel salt of the acid is the preferred form for additions if concentrations greater than about 1 gram/liter are added at one time. Of course, one would not use a copper or lead salt as this would introduce well-known harmful metal ions. In general, therefore, the nickel salt or free acid is preferred. It should be understood that when metasulfobenzoic acid is referred to herein, the expression includes the nickel salt of the compound. When the free acid is added to the nickel bath then due to the preponderance of nickel ions over hydrogen ions, the metasulfobenzoic acid is mostly in the form of the nickel salt or ionized nickel salt. Small percentages of ortho and para sulfobenzoic acid may be present in the metasulfobenzoic acid, though in general the more pure grades are preferred.

Besides the beneficial co-action of the metasulfobenzoic acid with formaldehyde, chloral hydrate and the aforementioned unsaturated compounds, it also cooperates to give ductile semi-bright nickel plate with other unsaturated compounds such as allyl alcohol and butyne diol, though in these latter cases, the cooperation is not quite as good as with the previously mentioned unsaturated compounds.

What is claimed is:

1. A bath for the electrodeposition of ductile low-stress nickel plate from an aqueous acidic nickel plating bath containing at least one nickel salt selected from the group consisting of nickel sulfate, nickel sulfamate, nickel fiuoborate, nickel bromide, and nickel chloride up to about grams/liter of NiCl .6H O and containing dissolved therein about 0.1 to about 10 grams/liter of metasulfobenzoic acid.

2. A bath for the electrodeposition of ductile semibright nickel plate of low stress from an aqueous acidic nickel plating bath containing at least one nickel salt selected from the group consisting of nickel sulfate, nickel sulfamate, nickel fluoborate, nickel bromide, and nickel chloride up to about 100 grams/liter of NiCl .6H O and containing dissolved therein about 0.1 to about 10 grams/ liter of metasulfobenzoic acid, and an unsaturated compound selected from the group consising of ll HCH CCI CHO, CBr CHO, CH =C-CH OC H SO H, HOC H OOH CECCH OC H OH, and HOCH -CECCH OC H SO H, in a concentration of about 0.01 to about 0.25 grams/liter.

3. A bath as claimed in claim 2 and wherein said unsaturated compound is formaldehyde in a concentration of about 0.01 to about 0.15 grams/liter.

4. A bath as claimed in claim 2 and wherein said unsaturated compound is chloral hydrate in a concentration of about 0.02 to about 0.25 grams/liter.

5. A method for the electrodeposition of ductile lowstress nickel plate comprising the step of electrodepositing semi-bright ductile nickel from an aqueous acidic nickel plating bath containing at least one nickel salt selected from the group consisting of nickel sulfate. nickel sulfamate, nickel fiuoborate, nickel bromide, and nickel chloride up to about 100 grams/liter of NiCl .6H O, and containing dissolved therein about 0.1 to about 10 grams/liter of metasulfobenzoic acid.

6. A method for the electrodeposition of ductile semibright nickel plate of low stress comprising the step of electrodepositing semi-bright ductile nickel from an aqueous acidic nickel plating bath containing at least one nickel salt selected from the :group consisting of nickel sulfate, nickel suldamate, nickel fluoborate, nickel bromide, and nickel chloride up to about 100 grams/liter of NiCl .6H O, and containing dissolved therein about 0.1 to about 10 grams/liter of metasulfobenzoic acid, and an unsaturated compound selected from the group consisting of 6 CClgCHO, CBr OHO, CHFC-CH OC H SO H, HOC2H4OCH2'CECCH2OC2H40H, and HOCH2CEC-CH2OC3H6S03H, in a concentration of about 0.01 to about 0.25 grams/ liter.

7. A method as claimed in claim 6 and wherein said unsaturated compound is formaldehyde in a concentration of about 0.0 1 to about 0.15 grams/liter.

8. A method as claimed in claim 6 and wherein said unsaturated compound is chloral hydrate in a concentration of about 0.02 to about 0.25 grams/liter.

References Cited by the Examiner UNITED STATES PATENTS 2,841,602 7/ 1958 Brown et a1. 204-49 X 2,849,353 8/1958 Kardos 20449 3,152,975 10/1964 Kardos ct a1. 204-49 JOHN H. MACK, Primary Examiner. G. KAPLAN, Assistant Examiner.

Claims

1. A BATH FOR THE ELECTRODEPOSITION OF DUCTILE LOW-STRESS NICKEL PLATE FROM AN AQUEOUS ACIDIC NICKEL PLATING BATH CONTAINING AT LEAST ONE NICKEL SALT SELECTED FROM THE GROUP CONSISTING OF NICKEL SULFATE, NICKEL SULFAMATE, NICKEL FLUOBORATE, NICKEL BROMIDE, AND NICKEL CHLORIDE UP TO ABOUT 100 GRAMS/LITER OF NICL2.6H2O AND CONTAINING DISSOLVED THEREIN ABOUT 0.1 TO ABOUT 10 GRAMS/LITER OF METASULFOBENZOIC ACID.