DE2045301A1 - Process for the production of a three-layer nickel coating - Google Patents

Description

ΡΛΤΕί. rA.VWÄLTE 2Q453Q1

Η.-NJtSOEN DAN K · dipl.-ing. H. HAITCK diii -.- i h \ s. W. SCHMITZ

HAMBURG-MÜNCHEN DELIVERY ADDRESS : HAMBURG 36 · NEW WALL ti

TIiL. »0 74 28 ITN D» 641 in 'TE I. »GH. ΝΕΟ 1! ΫΛ PATENT HAMBURG

MUNICH 15 ■ MOZARTSTR. 23

THE UDYLITE CORPORATION _TE1 . _{5; tsMSI1} '

■ 2 1 ^ h 1 Hoover Road tbleqr, nbcbbapatbsi μΟνοπβν

Warren, Michigan / USA

Hamburg, September 11th, 1997

Process for the production of a three- layer nickel coating

The Jirfindung relates to an improved method for ! Formation of a melir chi ent galvanic coating a base metal, particularly an improved method for the formation of a galvanic coating, consisting of three nickel coatings that border each other, as well as one nickel bath suitable for carrying out the process.

In the applicant's USA patent 3,090,733 a multiple

layered electroplating on the base metal

wrote, consisting of three adjoining nickel coatings exists, as well as a method for producing this coating. Wk: Disclosed in this patent is the coating of three layers of nickel applied one on top of the other hoHtjininiLon Dick «; built up with a nickel intermediate layer, which ο has a higher fjchwef elgehal fc than the neighboring ones both layers, and the top layer of nickel has one significantly higher sulfur content than the lower one.

1 0- D ft 1 5/1 7 Λ 6 ~ ² ~

As stated in this patent, the electroplating baths can contain various inorganic and organic sulfur-containing Compounds are incorporated from which the middle and upper nickel layers are deposited, to ensure the desired sulfur content of these layers. Sulfur-containing compounds that are used can, are z. B. thiosulfates, sulfites, bisulfites, hyposulfites, hydrogen sulfites, sulfoxylates, sulfites, ^ Thiocyanates, sulphoxides, sulphonic acids, mercapto-aromatic Acids, thiourea, isothiourea, thiohydantoin, Sulfamides, sulfimides, sulfonyl halides, sulfones and the like.

Although the ancestor described in this patent gives a much better protection against corrosion, even with a much thinner total thickness of the nickel deposit than has previously been possible when working showed certain difficulties after this procedure. if ™ ÄiXJBK the sulphurous bathslits are used Baths, as has been found, are opposite to air stirrers sensitive to high temperatures, which affects the speed, with which the deposition can be carried out is limited. In addition, the electrolytic removal of the metallic impurities such as zinc, copper itnd lead, which arise in the bathroom, i.e. the switching off of these metals is not effected until the sulfur-containing additives through Oxidation have been set. Daqtaodeutefc, daü after

1 fJ. <! ./ 1 746 - * -

Turning these metals off the sulfur-containing additives in the galvanic baths must be replaced before further deposition can be carried out. This is both time consuming and also costly.

The object of the invention is therefore to provide an improved method to form a three-layer Niekel coating that with higher Abseidungsgeschwindiglceiten can be carried out and from which metallic impurities

removes ^v

-en ■■ ..-...

will be able to create. In addition, a galvanic bath should be used for performing the method of forming the three-layer coating.

The object is achieved by a method for forming a multilayer nickel coating atif a corrosion-prone. Metal surface by galvanic deposition of a firmly adhered end lower layer of micrometers a thickness of about 3.81 to 38.1 / µm (0.15 to 1.5 mils) and an average j |

Sulfur content of less than about 0.03 fa _f Depositing an intermediate nickel layer firmly adhering to the lower layer with a thickness of about 0.127 to 508 / µm (0.005 to 0.2 mil) and an average sulfur content of about 0.05 to 0.3 ';<> and depositing an upper nickel layer adhering to the intermediate layer with a thickness of about 5 ° 8 to 38.1 _{μm (0 v} 2 to 1.5 ntil) and an average sulfur content of about 0.02 to 0.15 ^,

1f / 1746 - ^k - ■ '

.j ,. 20-5301

wherein the upper layer has a lower average sulfur content than the intermediate layer and a higher one than the lower layer. The method is characterized in that at least one thiosulfonate is added to the galvanic bath a nitrile or amide is added as a sulfur source for at least the middle or intermediate layer. It has been found that using thiosulfonates of nitriles or amides instead of the sulfur-containing compounds as described in US Pat. No. 3,090,733 are disclosed, the baths air-agitated and on higher Temperatures can be brought, which allows a faster deposition, and that metallic impurities, such as Zinc, copper and lead can be removed from the bath without the sulfur-containing compound first being oxidized would have to be destroyed.

More specifically, in the practice of the invention, thiosulfonates of nitriles or amides are used at least in the plating bath for forming the middle nickel-containing layer, and preferably in the plating baths for the two, middle and upper nickel layers, in order to keep the sulfur source in to provide these layers. As already noted above, the sulfur content of the middle nickel layer is preferably in the range from about 0.05 to 0.3 %, while in the upper layer it is in the range from about 0.02 to 0.15%

10 '' "./1746

the thiosulfonates of the nitriles or amides the galvanic baths for .ßrzeugting the intermediate layer in quantities in Ranges from about 0.01 to 0.4 g / l, preferably 0.03 to 0.1 g / l and used to produce the upper layer in amounts in the range from about 0.01 to 0.04 g / l. Of course, the exact amount in which the Thiosulfoiuite of nitriles or amides are to be used, depend on the particular compound or compounds used, so that in some cases they are in amounts outside of the above specified ranges are to be used so that the compound used is sufficient, the desired amount To give sulfur in the particular nickel layer.

The thiosulfonates of nitriles or amides that are used in the Methods according to the invention can be used are represented by the formulas below;

(A) "SO -R-S-R-CN

3 ' j (

(B) "SO ₃ -RSR ₁ -
| Cj SO, -RbR -

where R is an alkyl group with 2 to k carbon atoms and R _{1 is} either an alkyl group with 2 to 6 carbon atoms or an alkyl aryl group of the structure

in which R is an alkyl group with 2 to 4 carbon atoms, mean.

In general, these connections can through. implementation of a mercapto-alkyl sulfonate with a nitrile or a Amide can be produced.

Examples of compounds that are used in the erfindimgsgemäße Methods that can be used are the following;

II H H II (1) NC-C-C-C-C-CN

II · II II S

SSo ₃

II II

(2) HC - C - CH

• II

(CIiJ ₃

so ~

"7 _ 10 ■. /? 7 /,

II H Il HC - C - C. t II S. r (CIi ₂ ; S. I.

- NH,

SO,

H HC

H C

II

- CN

(CH,)

SO

II H H II H II Toilet - C - C - C - C - C - C. H H I. H H H S.

- CN

so.

O
it

-C-

(7)

C ι

S t

C H

C H

O ti

-C- NH,

SO,

II C

S ι

- CN

SO,

Particularly good results are obtained when the reaction product of mercapto-propylsulfonate with butylenedinitrile or acrylonitrile is used. Although specific references are made herein to these compounds as intended for use are preferred in the method according to the invention, this is not a limitation to this Thiosulfonates should be understood, rather they are only examples of such compounds.

When producing the three-layer nickel coating by the process according to the invention, it is possible to form

the lower layer is a nickel bath according to Watts for a matt finish Coatings and a bath for matte, semi-gloss or bright nickel coatings can be used to form the top layer, provided that the top has a higher sulfur content than the lower layer.

Although, g achieved with this three-layer Nickelüberzüg increased corrosion protection, even in the absence of a chromium overlay coating, it is preferred in many cases that the top layer of nickel with a final thin usual glossy or microcracked or microporous layer of chromium, suitably a thickness of about 0.000127 to 0 .00508 mm (0.005 to 0.2 mils). In general, it has been found convenient that the lower nickel layer be thicker than the upper; the preferred ratio is between about $ 0:50 to 80:20 in order to achieve the best ductility of the coating, but when ductility is not primarily important, "

thickness ratios of about k0: 60 are common. Excellent corrosion protection for the base metal surface is also obtained.

It should be noted that the nickel layers that make up the coating according to the invention can contain small amounts of other components in addition to sulfur, as are typical for such coatings, such as, for. Ii, carbon, selenium, tellurium, zinc, cadmium, and iron

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like that. In addition, these nickel layers can also contain significant amounts of cobalt, e.g. B. amounts of up to at least 50% cobalt can be contained in the nickel layers. Frequently, however, it has been found to be expedient for the lower nickel layer, if possible, to consist of pure nickel.

Accordingly, the lower nickel layer can consist of a nickel bath _ according to Watts, a fluoborate, a high chloride,

a SuIfamat nickel bath or a largely black / silver-free semi-gloss nickel bath. The baths from which the intermediate nickel layer is made can be of the same type as that used to deposit the lower layer, or an alkaline nickel bath or a high sodium, ammonium, lithium, or magnesium bath. The bath from which the intermediate layer is generated containing a course or more Tliiosulfonate of nitriles or amides, in the indicated further above W amounts to provide the desired amount of sulfur for this intermediate layer be ensured. Likewise, the electroplating baths from which the top layer is deposited can be the same as those used to create the intermediate layer, except of course that the concentration of sulfur compounds, such as the thiosulfonates of nitriles or amides, are lower than in the baths for the intermediate layer. If a decor itivex ^ coating is desired, the top nickel layer is made of

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a polished nickel bath in which one or more of the organic Sulib-oxy compounds listed in Table II U.S. Patent 2,512,280 and Table II of U.S. Patent 2 800 4 ^ IO are listed - the connections are also preferably used with unsaturated compounds or amines to achieve smoothness and gloss at the same time to get - are used.

These galvanic baths can also contain other components ^

contain, such as wetting agents to prevent hydrogen pores, buffers such as boric acid, formic acid, citric acid, acetic acid, Fluoboric acid and the like. For example, the baths can be used at temperatures in the range of room temperature, i.e. about 20 C to at least about 85 C and at pH values for acidic baths in the range from about 1 to 6 can be operated. It should be noted that the electroplating baths of this invention can be operated in the same way as in U.S. Patent '3,090,733 for creating the three-layer Nickel plating described. It has been found, however, § that when using the special sulfur-containing compounds, as described above, shorter ones Deposition rates are possible than when using of the compounds listed in the just mentioned USA patent, because air circulation and higher temperatures are possible and metal contaminants such as zinc, copper and lead can be removed electrolytically without the organic sulfur compounds are destroyed beforehand

10 - / 17 4

- 12 -

~ 12 -

have to. Thus, the process according to the invention can be used like that in US Pat. No. 3 ° 90 733 ^{for the} production of the three-layer nickel coating on steel, aluminum, zinc, magnesium, brass and similar corrosion-sensitive base metals, but brings a significant advance over this known process in that the certain and particular sulfur-containing compounds of the invention are used which have been found to be unique to the compounds disclosed in the United States patent.

In order to make the invention even clearer to the person skilled in the art and to show him how it is to be carried out, are the the examples below. In these examples, percentages and parts are given unless otherwise specified Based on weight.

EXAMPLE 1

Steel plates were provided with a three-layer nickel coating as indicated below:

15 / µm (0.6 mil) of a sulfur-free semi-bright nickel layer with a sulfur content of $ 0.003 «

1.5 / µm (Ο, Οό mil) of a high-sulfur nickel layer with a sulfur content of 0.1 ^ 3 %

1 ^i: ■ / 1 74 6 ■: - 13 -

by a concentration of 0.05 g / l of a reaction product of butanedinitrile and mercaptopropane sulfonate (1) in an air-stirred nickel bath at 6'J ° C (145 ° p).

1.0 / µm (0.4 mil) of a bright nickel layer of a sulfur content of 0.05 / ί.

This deposit was covered with a thin chrome coating, a thickness of 0.25 µm (0.1 mil), and then If the accelerated Corrodkote test was carried out "■ After 10 hours there was a missing point (rust spot), whereas the same plates without the high-sulfur intermediate layer had more than 25 missing points (rust spots).

IiKI GAME 2 ■ ■ - ■ - ■ -.

JSs a coating as described in Example 1 was produced

represents, except, -. that "the concentration of the thiosulfonate dinitrile was increased to 0.1 g / l. The sulfur content of the intermediate layer was increased to 0.22%. The three-layer nickel coating coated with -CIiiOiri. was considerably more sweet than a coating of the same thickness in which the high sulfur intermediate layer was omitted.

■ 1 ^r M 7 h 6

EXAMPLE 3

Plates were coated with a three-layer nickel like provided as follows:

10 / um (0, ^ mil) of a sulfur-free semi-bright nickel layer with a sulfur content of 0.003 fa,

1.75 / µm (0.07 mil) of a high-sulfur nickel layer with a sulfur content of 0.16>, obtained by a concentration of 0.09 g / l of the conversion product of propyl nitrile and mercaptopropyl sulfonate in an air-stirred nickel bath at a temperature of 60 C ( 1 hü Γ).

10 / uni (Ofk mil) a shiny nickel layer with a sulfur content of 0.05 / °

This coating was covered with a chrome layer of a thickness of 0.25 µm (0.01 mil) followed by the CASS test subject. After, '20 hours, there was no otel Ie aiii' that Base metal penetrated, whereas same plates without the high sulfur oil intermediate layer mohr a Is I'l Kehlste! Leu (Uoststellcn) showed.

iloispie.l. k

Ks were records with the dr «? Lychichtigeii Nicke lüborzug and

- 15 -

strand a chrome top coat, as described in Example 1, assuming that the perforated sulfur-containing layer had been applied (1) from a non-air-agitated nickel bath according to Watts at a temperature of k6 C (155 F) using Ό.2 g / l benzenesulfinate ( USA patent 3,090,733) and (2) an air-agitated Liickelbad according to Watts at a temperature of 63 C (1 ^ 5 P) using 0.0 ^ 5 g / l of the reaction product of butanedinitrile and mercaptopropyl sulfonate. a

After the plates 32 hours the accelerated Corrodkote test had been exposed showed the plates with the high sulfur layer made using Benzenesulfinate had been made 100 missing points (rust spots) while the plates made with the high sulfur content Schiclit using the Urasetzurgsprodukoe ■■ obtained from butanedinitrile and mercaptopropyl sulfonate had been, showed about 25 missing points (rust spots).

EXAMPLE 5

Comparative tests with regard to the stability of the bath additives in example A (i) and 3 in hot nickel solutions showed: i) after a nickel solution was kept at a pH of 1.5 and a temperature of 57.2 C (.1- 35 ^c ), k7 * £> of the benzenesulfonate were oxidized while

- 16 -

2) none after 2 ^ 1 hours under the same conditions Loss of the thiosulfonate of the dinitrile had occurred.

- 17 -

1 ^f - · - "■? /! 6

Claims (1)

2Ü45301 - 17 patent claims V1 ./ Process for the formation of a three-layer nickel coating on a corrosion-prone metal surface by galvanic deposition of a lower firmly adhering nickel layer with a thickness of 3 »81 to 38.1 / µm (0.15 to 1.5 mil) and an average sulfur content below 0, 03 ^, depositing a nickel layer firmly adhering to this lower layer with a thickness of 0.127 to 5.0.8 / µm (0.005 to 0.2 mil) and an average sulfur content of 0.05 to 0.3 ^c i ° and depositing an upper, on the intermediate layer firmly adhering nickel layer with a thickness of 5.08 to 38.1 / µm (0.2 to 1.5 mil) and an average sulfur content of 0.02 to 0.15 ^c / ° t , the upper layer being a lower one has an average sulfur content than the intermediate layer and a higher than the lower layer, characterized in that the galvanic bath contains at least one thiosulfonate of a nitrile or amide as Schwofe J .quo I le for at least the middle or intermediate layer is added, 2 . Vor / ahroii according to claim 1, characterized in that as a thiosulfonate of a Nifcril or Amld.s nine Vorhin dung, Hiifigtiwah I t from the sri l'Orinels listed below, is used by - 18 - 1 i. · '·' Ι 7 / -β Implementation of a mercaptoalkyl sulfonate with a Nitrile or an amide are available: (A) "SO-R-S-R-CN (B) "SO-RSR ₁ -C-NII (C) "SO ₃ -RSR ₁ - (CIl) wherein R is an alkyl group having 2 to C-h Äfcoraen mid R is either an alkyl group having 2 to 6 C-Atonen or Alkylary! group of the structure in which R is an alkyl group with 2 to h carbon atoms. 3. Procedure according to claim 2 , whereby ffckennztiiclmot, dui> die sulfur ellia L cowardly connection to the ";: ilvaiii" ciLon ilacl in a mengo from Opi to Ο, - 'l · g / l zjißeseifc ^ ic. H. Vorfiihreri according to claim 3 »thereby {? Ekmm: - * c glues, that di <i smolder" ο lha Lha L tige! Connection dom fja i VauiiKclieii had for the creation "tier * intermediate layer in von (), () ') bi.s O _t I g / 1 added wix'd » ^ll? BADORiQJNAL That the sulfur-containing compound is added to the electroplating bath to JSrzeuguiig · · of the upper layer in an amount of O to _P O1 Ο, Ο'ι g / l characterized in-5c Verfaliren according to claim 3 ». 6. Ver-fahr-s according to claim 3 »characterized in that as a sulfur-containing compound, the reaction product of mercaptopropane sulfonate and the dinitrile of butane is added. 7 · Procedure according to claim 3 »characterized in that as the sulfur-containing compound, the reaction product used by mercaptopropane sulfonate and acrylonitrile will. S. GalTranisches wrapping bath to carry out the procedure according to claims 1 to 7 for the formation of a nickel layer for a multilayer coating, characterized by an aqueous acidic nickel salt solution and at least f an organic sulfur-containing compound is selected from the group consisting of thiosulfonates from HiibriJen and amides in an amount that has a sulfur content ensures from 0.02 to $ 0.3 in the coating, 9. Galvanic bath according to claim 8, characterized in that that it contains thiosulfonates of nitriles or amides, which by reaction of a mercaptoalkyl - 20 - sulfonate obtained with a nitrile or an amide can be and under the following general Formulas fall: (A) "SO ₃ -RSR ₁ -CN
(Β) "SO-RSR ₁ -C ^ NH ₂
(C) "SO ₃ -RSR ₁ - (CN) ₂ where R is an alkyl group with 2 to h carbon atoms and R _{1 is} either an alkyl group with 2 to 6 carbon atoms or an alkyl-aryl group of the structure in which R "is an alkyl group with 2 to k carbon atoms. 10. Galvanic bath according to claim 9 »characterized in that the sulfur-containing compound in an amount from 0.01 to 0.4 g / l is present in the bath. 11. Bath according to claim 10, characterized in that the organic sulfur-containing compound is the reaction product of mercaptopropane sulfonate and butanedinitrile is. - 21 - ic ·, / <· 74 ₆ 12. Galvanic bath according to claim 10, characterized in that that the sulfur-containing compound is the reaction product of mercaptopropane sulfonate and acrylonitrile. 109315/174