GB2036800A

GB2036800A - Process for nickel electroplating and electroplating solution therefor

Info

Publication number: GB2036800A
Application number: GB7937506A
Authority: GB
Original assignee: M&T Chemicals Inc
Current assignee: M&T Chemicals Inc
Priority date: 1978-11-01
Filing date: 1979-10-30
Publication date: 1980-07-02
Also published as: JPS5569286A; CA1148496A; DE2943028A1; FR2440420A1; GB2036800B; DE2943028C2; BR7907042A; AU5235279A; AU534916B2; JPS6231076B2

Abstract

A nickel electrodeposit is prepared by passing electric current from an anode to a cathode through an aqueous electroplating solution containing at least one nickel compound and (i) 0.005-0.10 g per litre of an unsubstituted or substituted acetylenic amine and (ii) 0.005-0.25 g per litre of a sulphonated acetylenic compound or a salt thereof wherein the acetylenic bond and sulphonated radical are connected by a C1-C6 chain or an acetylenic compound having both characteristics (i) and (ii) in an amount of 0.005-0.35 g per litre.

Description

SPECIFICATION Process for nickel electroplating and electroplating solution therefor.

The present invention relates to a process for the preparation of a nickel electrodeposit and to an electroplating solution therefor.

To conserve nickel and reduce costs, a number of procedures have been adopted by the nickel plating industry. Some of these procedures include reducing the thickness of the nickel deposited, substituting cobalt for some or all of the nickel when cobalt is less expensive or more readily available, and more recently electrodepositing nickel-iron, cobalt-iron, or nickel-cobalt-iron alloys in which as much as 60% of the deposit may consist of relatively inexpensive iron.

However, when deposit thickness is reduced, it is necessary to use more effective or "powerful" nickel brighteners or higher concentrations of nickel brighteners, so that the degree of brightening and levelling to which the nickel plating industry has grown accustomed may be obtained. The more "powerful" nickel brighteners or high concentrations of brighteners, while capable of producing the desired brightening and levelling, may nevertheless cause unacceptable side effects. The deposits may peel or may be highly stressed, severely embrittled, less receptive to subsequent chromium deposits or exhibit hazes, reduced low current density covering power or "throw" or striations and skip plate i.e.; areas in which a deposit is not obtained.

in order to overcome or minimise the deleterious effects of "powerful" brighteners or high concentrations of brighteners, the addition of various sulphinic acids or their salts has been recommended by Brown in U.S. Patent Specification 2,654,703; the use of organic hydroxy sulphonates has also been recommended by Passal in U.S. Patent Specification 3,697,391 for this purpose.

Unfortunately these compounds severely reduce the deposit levelling and brightness range.

Further attempts have been made to improve low current density characteristics when "powerful" brighteners or high concentrations of brighteners are used, viz.: i) The use of aromatic monoamines, aromatic polyamines, unsubstituted polyethylenepolyamine by Du Rose in U.S. Patent Specification 3,630,857.

ii) The use of N-(3-sulphopropyl) pyridinium inner salts by Rosenberg in U.S. Patent Specification 3,862,019.

iii) The use of N-disubstituted amino propylene or its hydrochloride by Law in U.S. Patent Specification 4,054,495.

While these compounds do improve low current density characteristics, they still do not produce low current density deposits which are free from darkness and skip plate.

It is an object of this invention to provide processes and compositions for depositing electrodeposits of nickel which possess a greater tolerance for "powerful" brighteners and high concentrations of brighteners. It is also an object of this invention to accomplish this tolerance without affecting the levelling of the deposits. It is further an object of this invention to accomplish this tolerance while providing low current areas free from darkness and skip plate without affecting the bright range.

In accordance with one aspect of this invention there is provided a process for the preparation of a nickel electrodeposit, which comprises passing electric current from an anode to a cathode through an aqueous acidic electroplating solution containing at least one nickel compound, the electroplating solution containing (i) 0.005 to 0.10 gram per litre, preferably 0.01--0.04 g/l, of a substituted or unsubstituted acetylenic amine, and (ii) 0.005 to 0.25 gram per litre, preferably0.01-0.10g/l, of a sulphonated acetylenic compound or salt thereof where the acetylenic bond and sulphonate radical are connected by a carbon chain containing 1 to 6 carbon atoms, for a time sufficient to form a metal electroplate upon the cathode.

Examples of the said acetylenic amines are: 4-diethylamino-2-butyn-1 -ol 1,6-bis-(diethylamino)-2-hexyne 1 -dimethyla mino-2-propyne N-methylpropargyl amine propargyi amine 1 -diethylamino-2-propyne 5-dimethyla mino-2-methyl-3-pentyn-2-ol 1 -dimethyíamino-2-pentyne 3-methylamino-1 -butyne 1 -dimethylamino-2-hexyne 1 -dimethylamino-2-butyne 1 -diethylamino-2-butyne 1 -diethylamino-2-hexyne 4-diethylamino-1 -butyne 4-diethylamino-2-pentyne-4-ol 1,6-bis(morpholino)-2-hexyne 6-diethylamino-1 -piperidino-2-hexyne.

Examples of the said sulphonated acetylenic compounds of this invention are: 2-butyne-1 4-disulphonic acid 2-butyne sulphonic acid propargyl sulphonic acid 1 -butyne sulphonic acid 1-pentyne sulphonic acid.

In accordance with a second aspect of this invention there is provided a process for the preparation of a nickel electrodeposit which comprises passing electric current from an anode to a cathode through an aqueous acidic electroplating solution containing at least one nickel compound, the electroplating solution containing 0.005 to 0.35 gram per litre of an acetylenic compound which is both an amino compound and a sulphonated compound or salt thereof and wherein the acetylenic bond and sulphonate radical are connected by a carbon chain containing 1 to 6 carbon atoms, for sufficient time to form a metal electroplate upon the cathode.

In accordance with a further aspect of this invention there is provided an aqueous acidic electroplating solution as defined in the first and second aspects of the invention described above.

The electroplating solutions of this invention may also contain at least one substance chosen from: (a) Class I brighteners (b) Class II brighteners (c) Anti-pitting or wetting agents.

The term "Class I brighteners" are used herein, and as described in Modern Electroplating, Third Edition, F. Lowenheim, Editor, is meant to include aromatic sulphonates, sulphonamides, sulphonimides, etc., as well as aliphatic or aromatic-aliphatic olefinically unsaturated sulphonates, sulphonamides, sulphonimides, etc. Specific examples of such plating ,additives are: (1) sodium o-sulphobenzimide (2) disodium 1,5-naphthalene trisulphonate (3) trisodium 1,3,6-naphthalene trisulphonate (4) sodium benzene monosulphonate (5) dibenzene sulphonimide (6) sodium 3-chloro-2-butene-1 -sulphonate (7) sodium ,B-styrene sulphonate (8) monoallyl sulphamide (9) diallyl sulphamide (10) allyl sulphonamide.

Such plating additive compounds, which may be used singly or in suitable combinations, are desirably employed in amounts ranging from about 0.5 to 10 grams per litre and provide the advantages described in the above literature reference and which are well known to those skilled in the art of nickel electroplating.

The term "Class II brighteners" as used herein, and as described in Modern Electroplating, Third Edition, F. Lowenheim, Editor, 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 acetylenic compounds, N-heterocyclic compounds, dyestuffs, etc.

Specific examples of such plating additives are: (1) 1,4-di-(p-hydroxyethoxy)-2-butyne (2)1 1,4-di-(B-hydroxy-y-chloropropoxy)-2-butyne (3)1 ,4-di-(P-,y-epoxypropoxy)-2-butyne (4) ,4-di-(P-hyd roxy-y-butenoxy)-2-butyne (5)1 ,4-di-(2'-hydroxy-4'-oxa-6'-heptenoxy)-2-butyne (6) N-(2,3-dichloro-2-propenyl)-pyridinium chloride (7) 2,4,6-trimethyl N-propargyl pyridinium bromide (8) N-allylquinaldinium bromide (9) 2-butyne-1 ,4-diol (10) propargyl alcohol (11) 2-methyl-3-butyn-2-oI (12) quinaldyl-N-propanesulphonic acid betaine (13) quinaldine dimethyl sulphate (14) N-allylpyridinium bromide (15) isoquinaldyl-N-propanesulphonic acid betaine (16) isoquinaldine dimethyl sulphate (17) N-allylisoquinaldine bromine (18) 1,4-di-(p-sulphoethoxy)-2-butyne ( 1 9) 3 -(P-hyd roxyethoxy)-propyne (20) 3-(p-hydroxypropoxy)-propyne (21) 3-(P-sulphoethoxy)-propyne (22) phenosafranin (23) fuchsin.

When used alone or in combination, desirably in amounts ranging from about 5 to 1000 milligrams per litre, a Class II brightener may produce no visual effect on the electrodeposit, or may produce semi-lustrous, fine-grained deposits. However, best results are obtained when Class II brighteners are used with one or more Class I brighteners in order to provide optimum deposit lustre, rate of brightening, levelling, bright plate current density range, low current density coverage, etc.

The term "anti-pitting or wetting agents" as used herein is meant to include a material which functions to prevent or minimize gas pitting. An anti-pitting agent, when used alone or in combination, desirably in amounts ranging from about 0.05 to 1 gram per litre, may also function to make the baths more compatible with contaminants, such as oil, grease, etc. by their emulsifying, dispersing, solubilizing, etc. action on such contaminants and thereby promote attaining of sounder deposits.

Preferred anti-pitting agents may include sodium lauryl sulphate, sodium iauryl ether-sulphate and sodium dialkylsulphosuccinates.

The nickel compounds employed for electrodepositing nickel are typically added as the sulphate, chloride, sulphamate, or fluoborate salts. The sulphate, chloride, sulphamate and fluoborate salts of nickel are generally employed in concentrations sufficient to provide nickel in the electroplating solutions of this invention in concentrations ranging from about 10 to 150 grams per litre.

The nickel electroplating baths of this invention additionally may contain from about 30 to 60 grams per litre, preferably about 45 grams per litre of broic acid or other buffering agent to control the pH (e.g. from about 3.5 4.5, preferably 4.0) and to prevent high current density burning.

In order to prevent "burning" of high current density areas, and provide for more uniform temperature control of the solution, solution agitation may be employed. Air agitation, mechanical stirring, pumping, cathode rod and other means of solution agitation are all satisfactory. Additionally, the solutions may be operated without agitation.

The operating temperature of the electroplating baths of this invention may range from 400C to 700C, preferably from 500C to 620C.

The average cathode current density may range from about 0.5 to 12 amperes per square decimetre, with 3 to 6 amperes per square decimetre providing an optimum range.

Typical aqueous nickel-containing electroplating solutions (which may be used in combination with effective amounts of cooperating additives) include the following wherein all concentrations are in grams per litre (g/l) unless otherwise indicated.

TABLE f Aqueous Nickle-Containing Electroplating Solutions.

Minimum Maximum Preferred Component: NiS04.6H20' 75 500 300 Ni Cl2.6H20 20 135 60 H,B6, 30 60 45 pH (electrometric) 3.5 4.5 4.0.

During bath operation, the pH may normally tend to rise and may be adjusted with acids such as hydrochloric acid, sulphuric acid, etc.

Anodes used in the above baths may be electrolytic or sulphur containing nickel bars, strips or small chunks in titanium baskets. All anodes are usually suitably covered with cloth or plastic bags of desired porosity to minimize introduction into the bath of metal particles, anode slime, etc. which may migrate to the cathode either mechanically or electrophoretically to give roughness in cathode deposits.

The substrates on which the nickel electrodeposits of this invention may be applied may be metal or metal alloys such as are commonly electrodeposited and used in the art of 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 iron, steel, alloy steels, copper, tin and alloys thereof such as with lead, alloys of copper such as brass, bronze, etc., zinc, particularly in the form of zinc-base die castings; all of which may bear plates of other metals, such as copper, etc. Basis metal substrates may have a variety of surface finishes depending on the final appearance desired, which in turn depends on such factors as lustre, brilliance, levelling, thickness, etc. of the nickel electroplate applied on such substrates.

While nickel electrodeposits can be obtained employing the various parameters described above, the brightness, levelling, ductility and covering power may not be sufficient or satisfactory for a particular application. In addition the deposits may be-hazy or dull, and also exhibit striations, skip plate, peeling, poor brightness range or poor chronium receptivity. These conditions may especially result after the addition of excessive replenishment amounts of Class II brighteners, or from the use of especially powerful Class II brighteners.

By adopting the present invention the aforementioned deficiencies will be corrected to a satisfactory degree.

Additionally when used together, compounds from these classes will permit the use of higher than normal concentrations of Class II brighteners, thus permitting higher rates of brightening and levelling without the undesirable striations, skip plate, poor brightness range, etc. normally expected under these conditions.

Compounds exemplifying the two components (i) and (ii) in accordance with the first aspect of this invention are unusual in that they act synergistically together to produce sound low current density deposits substantially free from darkness, striations, skip plate, etc. without affecting levelling or the brightness range of the electrodeposit in the presence of "powerful" or high concentrations of Class II brighteners. These compounds when used independently of one another and in the presence of "powerful" or high concentrations of Class II brighteners still produce electrodeposits exhibiting one or more of the following effects: low current density darkness, striations, skip plate, poor brightness range.

The following examples illustrate the invention except for Panel 1 which is comparative.

TABLE II Compositions in g/jitre

Panel ' Panel Panel Panel Panel 1 2 3 4 5 NiSO4.6H,6- 300 300 300 300 300 NiCi2.6H2O 60 60 60 6a 60 K,'BO 45 45 45 1 45 45 pH 4.0 4.0 4.0 4.0 4.0 temperature 600C 600C 600C 600C 600C sodium o-sulpho- 1.35 1.35 1.35 1.35 1.35 benzimide propargyl alcohol 0.005 0.005 0.005 0.01 0.005 monoethoxylated 0.01 0.01 0.01 0.01 0.01 propargyl alcohol 1-diethylamino-2- Nil 0.02 0.025 Nil 0.02 propyne sodium salt of propargyl sulphonic acid Nil 0.1 0.05 0.15 0.02 2-butyne- 1,4-diol Nil Nil 0.02 Nil Nil 4-dietylamino-2- Nil Nil Nil 0.01 Nil pentyn-4-ol It will be seen that for Panel 1 (comparative) no component (i) is present.For each of Panels 2-5 (illustrative of the invention) the sodium salt of propargyl sulphonic acid is used as component (ii) and for each of Panels 2, 3 and 5 1-diethylamino-2-propyne is used as component (i) and for Panel 4 4 diethylamino-2-pentyn4-ol as used as component (i).

The conditions for plating the panels from the above aqueous nickel electroplating compositions were as follows: A zinc coated steel panel was stripped in 50% hydrochloric acid, rinsed, and then scribed with a horizontal single pass of 4/0 grit emery polishing paper and 2 grit emery polishing paper.

The cleaned panel was then plated in a 267 ml Hull Cell using the aforementioned compositions for 10 minutes at 2 amperes cell current, using cathode rocker agitation.

OBSERVATIONS: Panel No. 1 - shows a ductile deposit with fair brightness and levelling, low current density darkness skip plate, hazing at 2-4 asf and a thin plate area at 0--13 asf.

Panel No. 2 - shows a bright well levelled, ductile deposit free from low current density defects and a uniform brightness range.

Panel No. 3 - shows a ductile deposit with grood brightness and levelling, excellent brightness range, freedom from low current density darkness and skip plate.

Panel No. 4- shows a ductile deposit with good brightness and levelling, good brightness range, and freedom from low current density darkness and skip plate.

Panel No. 5 - shows a ductile deposit with good brightness and levelling, uniform brightness range, and freedom from low current density defects.

Claims

1. A process for the preparation of a nickel electrodeposit which comprises passing electric current from an anode to a cathode through an aqueous acidic electroplating solution containing at least one nickel compound, the electroplating solution containing: (i) 0.005 to 0.10 gram per litre of an unsubstituted or substituted acetylenic amine, and (ii) 0.005 to 0.25 gram per litre of a sulphonated acetylenic compound or a salt thereof wherein the acetylenic bond and sulphonate radical are connected by a carbon chain containing 1 to 6 carbon atoms, for sufficient time to form a metal electroplate upon the cathode.

2. A process for the preparation of a nickel electrodeposit which comprises passing electric current from an anode to a cathode through an aqueous acidic electroplating solution containing at least one nickel compound, the electroplating solution containing 0.005 to 0.35 gram per litre of an acetylenic compound which is both an amino compound and a sulphonated compound or salt thereof and wherein the acetylenic bond and sulphonate radical are connected by a carbon chain containing 1 to 6 carbon atoms, for sufficient time to form a metal electroplate upon the cathode.

3. A process according to Claim 1 or Claim 2, wherein the electroplating solution contains 10 to 1 50 grams per litre of nickel.

4. A process according to any preceding claim, wherein the electroplating solution contains one or more of nickel sulphate, nickel chloride, nickel sulphamate, nickel fluoborate.

5. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 4 diethylamino-2-butyn-1 -ol.

6. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1,6 bis-(diethylamino)-2-hexyne.

7. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1 dimethylamino-2-propyne.

8. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is N methylpropargyl amine.

9. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is propargyl amine.

10. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1 diethyiamino-2-propyne.

11. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 5 di methylamino-2-methyl-3-pentyn-2-ol.

12. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1 dimethylamino-2-pentyne.

13. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 3methylamino-1 -butyne.

14. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1 dimethylamino-2-hexyne.

1 5. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1 dimetllylamino-2-butyne.

16. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1 diethylamino-2-butyne.

1 7. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1 diethylamino-2-hexyne.

1 8. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 4diethylamino-1 -butyne.

19. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 4diethylamino-2-pentyn-4-ol.

20. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 1 ,6-bis-(morpholino)-2-hexyne.

21. A process according to Claim 1 or Claim 3 or Claim 4, wherein the said acetylenic amine is 6diethylamino-1 -piperidino-2-hexyne.

22. A process according to Claim 1 or Claim 3 or Claim 4 or any one of Claims 11 to 21, wherein the said sulphonated acetylenic compound is 2-butyne-1 ,4-disulphonic acid.

23. A process according to Claim 1 or Claim 3 or Claim 4 or any one of Claims 11 to 21, wherein the said sulphonated acetylenic compound is 2-butyne sulphonic acid.

24. A process according to Claim 1 or Claim 3 or Claim 4 or any one of Claims 11 to 21, wherein the said sulphonated acetylenic compound is propargyl sulphonic acid.

25. A process according to Claim 1 or Claim 3 or Claim 4 or any one of Claims 11 to 21, wherein the said sulphonated acetylenic compound is 1 -butyne sulphonic acid.

26. A process according to Claim 1 or Claim 3 or Claim 4 or any one of Claims 11 to 21 , wherein the said sulphonated acetylenic compound is 1-pentyne sulphonic acid.

27. A process according to Claim 1 substantially as herein described and exemplified.

28. An electroplated article which has been produced by a process as claimed in any preceding claim.

29. An aqueous acidic electroplating solution as defined in any one of Claims 1 to 26.

30. An aqueous acidic electroplating solution substantially as herein described and exemplified.