DE2122455B2 - Aqueous solution for the electroless deposit of a nickel-copper-phosphorous alloy with a maximum of 25% by weight of copper - Google Patents

Description

The object of the invention is therefore to provide an aqueous

35 Solution for the electroless deposition of a nickel

containing coating, with the help of which

it is possible to be smooth, pore-free and from surface defects to produce free coatings of nickel or nickel alloys.

40 It has now been found that this object can be achieved by an aqueous Solution for the electroless deposition of a nickel-copper-phosphorus alloy with a maximum of 25 parts

The invention relates to an aqueous solution for the weight percent copper used in addition to electroless nickel Deposition of a nickel-copper-phosphorus ion, hypophosphite as a reducing agent for the Alloy with a maximum of 25 percent by weight copper, nickel ions, a buffer to adjust the pH Nickel ions, hypophosphite as a reducing agent value nor copper (I) ions with / or copper (II) for which contains nickel ions, a buffer for adjusting the ions and is practically free of a sulfur pH value and contains copper ions, to produce a compound that is sulfide and / or in the solution of surface coatings with an improved 50 hydrosulfide ions.

Appearance. When using the above-described,

Solutions and methods for electroless deposition - the subject of the invention forming aqueous coating of nickel-containing coatings on a solution one obtains shiny nickel alloy over-substrate are for example from the US patents, which are extremely corrosion-resistant th 26 90 401, 26 90 402, 27 62 723, 29 29 742, 55 and are already known to be excellent as decorative protective coatings 29 25 425 and 33 38 7-6. Others are suitable. With the aid of the aqueous solutions suitable for the deposition of nickel solution according to the invention, smooth, pore-free and surface and nickel alloys are practically free of surface defects in the 35th annual surface coatings would be produced in the Metal Finishing Handbook, 1967, Metal and Plastics Publications, Inc., Westwood. New 60 sen, do not tarnish and their corrosion-resistant jersey, pp. 483 to 486, described. The known aqueous solutions are 5 times better than the corrosion resistance of the loose deposits of nickel coatings contained in the previously known nickel coatings, determined in the salt spray test,
general nickel ions, a reducing agent such as an extremely important feature of the 1. B. hypophosphite, a buffer for adjusting the 65 claimed aqueous solution is the fact that the desired pH and a complexing agent it is free of sulfur compounds, which in the Lö for the metal ions, which are precipitated from the solution by sulfide and / or hydrosulfide ions. Wähjung should prevent. the previously known aqueous electroless loading

3 4

coating baths always use sulfur or sulfur compounds in aqueous solution

dung contained in stabilizing amounts because trains.

Sulfur is known as an excellent bath stabilizer As already mentioned, it is assumed that the cupist, According to the application it is also the fer (I) ions for the increased stability of the bath, which last traces of sulfur compounds, which in the 5 increased corrosion resistance of the deposit and Solution supply sulphide and / or hyposulphide ions, because the improved appearance of the deposit is responsible, to indicate a bath, with the help of which it is on high and that the copper (II) ions ~ a deposit surprisingly effective way is possible to deliver bright, strong tion with an improved appearance. As a result, glossy, to produce ductile coatings. A stage can lead to electroless nickel deposit bilization the aqueous solution according to the invention io approximate solution both copper (I) and copper (II) through Sulphide ions or hydrosulphide ions are not to be added, the copper (I) compounds being required. It is believed that those in the invention compounds are preferred.

according to the aqueous solution contained Kup- Both the simple and the complex, in

fer (I) ions have a stabilizing effect on the copper that is soluble in the electroless coating solution

have aqueous solution. i ₅ ferrous compounds are used as a source for the copper ions

From "Metallwissenschaft und Technik", February suitable for the purposes of the present invention.

1960, No. 2, pp. 109 to 112, it has already been Typical examples of suitable compounds are

knows that copper (I) ions in aqueous coating- copper (l) acetate, copper (II) acetate, copper (I) -ben-

treatment baths electroless nickel deposition bezoate, copper (II) benzoate, copper (I) bromide, copper

accelerate, from a stabilizing effect on ao fer (II) citrate, copper (II) bromide, copper (I) carbonate,

the aqueous bath and the use of copper (II) carbonate, copper (I) chloride, copper (II) -

Copper (I) ions in sulfur-free coating chloride, copper (I) fluoride, copper (II) fluoride, copper

bathing is not mentioned in it. fer (II) nitrate, copper (I) hydroxide, copper (II) sulfate,

Similar, albeit less advantageous, Er- copper (I) ammonium chloride and copper (II) ammonium

Results are obtained when the aqueous solution is 25 sodium chloride.

The invention, which is practically free of a sulfur compound, can be used to keep the copper in solution, which sulphide and / or complexing agents may be required in the solution, in particular when it provides hydrosulphide ions and adds copper (II) ions. if the copper is present in comparatively large quantities this will also change the appearance of the under-use. Complexing agents for copper are known and, for example, in the US patents approximately improved coatings, even if 29 38 805, 33 12 430 and 33 83 224 are described using nickel alloys produced using this solution.
Stability of this solution and the corrosion resistance. With regard to the copper (I) compound, the coatings produced with it should be pointed out somewhat less that many of these compounds are not completely soluble in water than when using copper (I) ions or solution and are not completely soluble that some of a combination of copper (I) - and copper (II) - 35 _{SO are} completely insoluble. The copper (I) compound is jeionen. If the aqueous solution of the invention contains only copper (II) ions for the purposes of the present invention, it is expedient to add one to it in such an amount that the other bath stabilizer is concentrated in which it contains copper (I) ions. ions in the order of magnitude is not a sulfur compound, which only provides a few ppm (parts per million). As a result, solution delivers sulfide and / or hydrosulfide ions. 40 of which it is sufficient if copper (I) compounds that

The aqueous solution forming the subject of the invention is regarded as practically insoluble in aqueous solution

rige solution for the electroless deposition of a be, are soluble to such an extent that

Nickel-copper-phosphorus alloy with at most they provide copper (I) ions whose concentration is for

25 percent by weight copper, which, in addition to nickel ions, is sufficient for the purposes of the present invention.

Hypophosphite, a buffer and copper (I) - and / or ₄₅ Easily soluble copper (I) compounds are however

Copper (II) ions optionally also a grain preferred.

plexing agents for the nickel and / or copper ions. When they are used, they are deposited during formation

may contain, preferably has a pH of metal deposits from the coating solution

between 4.0 and 13.0, in particular between 4.0 and copper and nickel together from with the formation of a

5.5, and it preferably contains 5 to 200, ins- 50 nickel-copper-phosphorus alloy. There are several

especially 15 to 100 ppm copper (I) ions. Factors contributing to the amount of in the electroless

The invention is described below with reference to the alloy of commonly deposited copper in

explained in more detail on the drawings. Dab? I shows a drawing. One such factor is, for example

F i g. 1 is a graph of the copper- the pH of the solution, and it has been found

concentration in a nickel-copper-phosphorus 55 that a low pH, especially below

Alloy coating as a function of the pH value of 4.5, a higher concentration of the co-deposited

electroless aqueous coating solution, favored with its copper. The relationship between the

The coating has been made, the pH of the solution and the concentration of the

F i g. FIG. 2 is a graph of the copper deposited in FIG. 1 shown in the

concentration in a nickel-copper-phosphorus 60 for explanatory purposes the electroless solution of the

Alloy coating as a function of the copper ions - Example 1 below under the specified

concentration was used in the conditions used for its production, the 200 ppm

the electroless aqueous coating solution. Copper (I) ions in the form of copper (I) chloride added

F i g. 3 four photomicrographs of the surface had been given. The pH was varied by different Alloy coatings with and without 65 would be adjusted from ammonium hydroxide. From Fig. 1 Copper and / or with precipitated sulfur and it can be seen that the copper deposition is considerable

Fig. 4 two photomicrographs of the cross-section increasing when the pH falls below 5.0,

tes of two using the invention- Another factor affecting the copper concentration

What seems to affect the deposit is the copper concentration in the plating solution. This relationship is shown in FIG. 2 for an acid bath, curve A illustrating the relationship between the content of copper (I) ions in the solution and the copper content in the nickel deposit obtained, while curve B illustrates the relationship between the copper (II) content in the solution and the copper content in the deposit. The electroless deposition solution is that of Example 1 given below using the conditions given.

A third factor that appears to affect the concentration of copper in the deposit is temperature the solution. It has been found that in acid baths with a pH between about 4.0 and 5.0, the concentration of copper in the deposit increases significantly as the solution temperature drops to a value below about 88 ° C.

From the above it can be seen that the copper content in the deposit is proportionate can be high compared to the copper hook in the solution, especially if the solution is at low pH, low solution temperature, or both. The above attempts show that copper deposition can and can be preferred to nickel deposition frequent regeneration with a copper salt may be necessary. Usually the copper concentration varies in the deposit between 0.1 and 12 percent by weight, but it can also be up to 25 percent by weight, especially in thin deposits, e.g. B. those with a thickness of 0.635 mm or less.

The numerical value for the copper concentration given in the deposit in the drawings can be a bit misleading. Without being bound by theory, it is believed that at least in acidic solutions with a pH value of less than 5 on a highly active surface the copper first alone or together with some nickel in the form of a thin film and then together with Nickel with the formation of a first layer, which is highly concentrated in copper, which is combined with Nickel and copper plated is deposited. It is believed that this is particularly the case at low pH of the solution and at a low bath temperature applies. As a result, it is believed that the total thickness of the deposit obtained from a boundary layer connected to the coated substrate in Contact is with the highest concentration of co-deposited copper and that of the substrate furthest surface with the lowest copper concentration, with between a copper concentration gradient exists in these two layers. If during the deposit If the solution is regenerated with copper for a certain substrate, then a Structure where the concentration is high in the part of the deposit that is at the time of regeneration is formed, a new copper concentration gradient being created. This is shown in FIGS. 4 A and 4 B explained, which represent cross-sections through deposits, wherein in F i g. 4 A during the deposit was regenerated twice, while in FIG. 4 B was not regenerated. The layer structure is off F i g. 4 A clearly visible.

The amount of tolerable copper in the solution depends on various factors. For example leads to a change in the basic solution, e.g. B. a change in relation to the complexing agent, a Change in relation to the nickel or hypophosphite content, to a change in the maximum Amount of copper tolerable in the solution. In addition, the working conditions, e.g. B. the pH host and the temperature, factors related to the maximum copper content in the solution

ίο stand. In this regard it is preferred among Working conditions the content of copper (I) ions in the solution is preferably between 5 and 200 ppm the solution, in particular between 15 and 100 ppm of the solution held. Preferred according to the invention Working conditions are a pH between 4.0 and 7.0, preferably between 4.0 and 5.5. Within the pH range from 4.0 to 5.5 is a preferred working temperature for the electroless Solutions at at least 88 ° C. Under these conditions are at a relatively high concentration the solution of copper (I), e.g. B. of more than about 200 ppm, for reasons that have not yet been clarified, Deposits with a matt rather than glossy appearance and a grainy structure are obtained. It It should be noted that the copper ion concentration ranges given here are guidelines only and that the copper ion concentration in the solution is most suitably kept at a value that is sufficient to achieve the goals stated above

an improved corrosion resistance wedge and a to achieve an improved appearance while at the same time avoiding the formation of powdery matting Deposits.

As already stated above, increased bath stability is obtained when the copper is in the form of Copper (I) ions is present. Although electroless nickel solutions have been used for many years, The baths used to date have the disadvantage, as is known, that they are relatively result in low deposition rates and are unstable. It was also found that the rate of deposition to some extent on the concentration of the reducing agent or of the nickel ions present in the solution depends and that a higher concentration generally leads to a higher deposition rate leads. However, a higher concentration of reducing agent and / or nickel ions leads to a lower bath stability. This is expressed in a

5 "Reduction of the period within which the Solution is subject to uncontrollable decomposition. It is also known that certain additives that be added to an electroless nickel solution, in properly controlled trace amounts, as stabilizers act and retard the rate of bath decomposition. In general, however, these stabilizers represent catalytic poisons and their concentration in the solution is very critical. Trace amounts, preferably within the range of a few ppm

of the solution, lead to stabilization depending on the particular stabilizer used. An excess on the stabilizer, however, partially or completely stops the electroless deposition of metal.

One such stabilizer that is also a catalytic

Is poison is described in US Pat. No. 2,762,723, for example. In this patent there is one acidic nickel plating solution described which stabilizes with sulfide ions and a "sulfide ion regulator"

is sated, which combines with the sulficlions to prevent release from a hot or boiling solution. Such sulfide ion regulators are lead, bismuth, tin, selenium, tellurium, tungsten, thorium, titanium, copper, zinc, manganese and rhenium. The sulfide ions, which are the active constituents of the stabilizing combination, are catalyst poisons and as such reduce and prevent the rate of deposition in trace amounts the deposition of larger quantities. According to the present invention, with small amounts of copper (I) ions, one becomes essential better stability is achieved, and there is only a negligible effect on the rate of deposition, since copper (T) ions are not a catalyst poison represent.

Regarding the use of sulfide ions as a stabilizer, as described in US Pat. No. 2,762,723 indicated, it has been found that the presence of sulfide ions or any other sulfur compound, which is deposited together with the Ni-Cu-P alloy at least partially without current and / or dissociates with the formation of sulfur in the solution in the form of the sulfide or hydrosulfide ion, detrimental both to the appearance of the deposit and to its other properties, such as the corrosion resistance, is. Although the addition of copper to the solution creates a nickel-copper-phosphorus alloy deposit supplies that are smooth and dense and therefore shiny in appearance and corrosion resistant, these go beneficial Properties lost when in the coating solution of the type described too Sulfur is present. Sulfur compounds that are tolerated in the solution to a limited extent can are those that are covalently bonded to carbon atoms, thereby introducing the sulfur in the form of sulfide or hydrogen sulfide ions is prevented from entering the solution. The watery one Solution of the invention is preferably free of sulfur compounds which dissociate in solution with the formation of detrimental sulfide and hydrosulfide ions, and most preferred are such Solutions that are free from all sulfur compounds.

The effect of sulfur in the solution is readily apparent from FIG. 3 which shows four photomicrographs illustrating the surface of four nickel deposits magnified 5000 times. Microphotograph A shows a deposit of a nickel-phosphite solution free of both copper and sulfur compounds. From this it can be seen that the deposit has a rough, irregular appearance. Photomicrograph B shows a deposit from the same solution but containing 10 ppm thiourea based on the solution. There is little difference between the deposits in photomicrographs A and B. Photomicrograph C shows a deposit made from the same solution as A , but containing 100 ppm cupric chloride, based on the solution. A comparison of photomicrograph C with photomicrographs A and B shows the sharp contrast which consists in the fact that no imperfections are seen at all on the surface of the deposit shown in photomicrograph C. Photomicrograph D shows a deposit from the same solution as photomicrograph C but containing 100 ppm thiourea in the deposit. From this it can be seen that the deposit has a rough surface which is only slightly improved over the deposits shown in photomicrographs A and B.

The particular selected as the source of the copper ions for the purposes of the present invention Copper compound is not critical as long as it provides enough copper ions and as long as the anion

ίο the copper compound on the coating solution exerts no adverse influence. For example, it is known that certain anions are sufficient in large quantities, such as B. cyanide, are detrimental to electroless plating solutions, and salts, which these anions or other anions known to be harmful should be avoided.

The solution according to the invention can be hypophosphite contained as reducing agent. It is known that the deposit obtained is used as an alloying element

ao contains phosphorus when the phosphorus content is usually within the range of 5 to 15 percent by weight depending on numerous factors such as B. the ratio of hypophosphite to Nickel in the solution, the pH of the solution

and the like. The most common range for such deposits using commonly known ones Procedure varies between 5 and 10%, although if desired higher phosphorus contents within the range between 10 and 15% are also available are.

The electroless nickel alloy coating solution of the present invention is used in the same way to deposit a nickel alloy like the well-known electroless nickel solutions.

The surface of the substrate to be coated should be free of grease and impurities. When a If the non-metallic surface is to be coated, the surface area on which the deposit is to be deposited must be is to be applied, first be sensitized to him for the reception of the currentless applied To make nickel alloy coating receptive by treating it in a manner known per se with a acidic aqueous solution of tin (II) chloride and then with a dilute aqueous acidic Treated solution of palladium chloride. Sensitization of non-metallic surfaces can can also be achieved by bringing them into contact with a catalyst, by mixing of tin (II) chloride and a noble metal chloride, preferably palladium chloride was, with the tin (II) chloride in stoichiometric Excess over the amount of noble metal chloride is present.

For a better understanding, the invention ar the following examples is described in detail, ir which the stability of a solution was determined by the time elapsed, decomposed spontar to a bath when a catalyzed tissue or ^akt: fourth aluminum was coated. The depositing properties were by coating a; chrome-plated steel substrate. The catalyzed fabric was made by treating a cotton fabric according to the following steps:

1. Rinsing the tissue for 5 minutes in a 20 weight percent ammonium hydroxide solution which was kept at room temperature, from rinsing with cold water;

609 510 / 3S

2. Rinsing for 5 minutes with a 20% acetic acid solution which was kept at room temperature, Rinse with cold water;

3. Immerse the tissue in a sensitizing solution for 20 to 40 seconds Palladium colloids with a tin (IV) acid cliioid, kept at room temperature, rinsing with cold water;

4. 1 to 3 minute immersion in a diluted, hydrochloric acid solution kept at room temperature, rinsing with cold water;

5. Dry the fabric and cut it to the appropriate size.

The activated aluminum used was one obtained by immersion for 2 minutes a 37% hydrogen chloride release activated 2024 alloy.

In all examples, 930 cm ^{2 of} the catalyzed tissue or of the activated aluminum per 3.79 1 of solution were used to initiate the deposition and the spontaneous decomposition to determine the stability. To avoid contamination from contaminants, distilled water and reagent grade chemicals were used.

example 1

Nickel sulfate hexahydrate 35 g

Sodium hypophosphite monohydrate 15 g

Sodium acetate 15 g

Water ad 11

Temperature 91 to 96 ° C

pH 5.0

The activated aluminum caused the above bath to decompose within Minutes with severe build-up on the sidewalls within about 8 minutes. When 50 ppm of cuprous ions [in the form of cuprous chloride] were added to the bath, decomposed it does not change within 60 minutes.

This bath decomposed in about 20 minutes using activated aluminum. When adding 50 ppm, based on the solution, of copper (I) ions in the form of copper (I) chloride] no decomposition occurred for 40 to 45 minutes.

Example 3

Nickel chloride hexahydrate .... 30 g

Sodium hypophosphite monohydrate 10 g

Ammonium chloride 25 g

Ammonium hydroxide except for one

pH 8.5

Water ad 11

Temperature 82 ⁰ C

The addition of the catalyzed tissue to the obi-

The solution caused its decomposition within about 1 to 2 minutes. When adding about 25 ppm of copper (I) ions in the form of copper chloride no decomposition occurred within 4 minutes. When the copper (l) ion content is increased

to 40 ppm based on the solution, no decomposition occurred for about 7 to 8 minutes. An increase of the copper (I) ion content ·. to 50 ppm based on the solution, decomposed in about 10 to 12 minutes. When finally the

Copper (I) ion content increased to 200 ppm of the solution no decomposition occurred for 12 to 15 minutes however, the appearance of the deposited nickel was dull and had a powder structure (granular structure). From the above is to

see that the copper (I) ion stabilizer is more effective in acidic nickel baths than in alkaline baths Badern that in the latter, however, a certain improvement is also achieved.

Example 2

Nickel chloride hexahydrate .... 30 g

Sodium hypophosphite monohydrate 10 g

Ammonium chloride 100 g

Ammonium hydroxide except for one

pH of 9

Water ad 11

Temperature 91 to 96 ° C

Examples 4 to 10

Nickel sulfate hexahydrate 35 g

Sodium hypophosphite monohydrate 15 g

Sodium acetate 15 _g

Sulfur stabilizer 1) 5 _ppm

Water _{ad n}

Temperature 91 to 96 ⁰ C

P ^H value about 5.0

') Admitted in the form of thiourea.

fm ^e £ ^u P ^fer (I) ions were in the form of Kup ⁿ '* ^nd added and ^urde to determine stability in the above described manner ™ ^{e' n} used catalyzed tissue. The gloss and corrosion resistance were also determined, with the following results being obtained

example

No. ¹ )

Copper (l) -gchalt

(ppm)

Gloss () corrosion resistance ^{: l} )

Stability (minutes)

strong gas formation within> 60 30 seconds, immediate formation of
black dirt

Gas formation in 3Va minutes,> 60

black stripes in 1 minute

Gas formation in 40 minutes,> 60

black stripes in 14 '/ 2 minutes

no gas formation or formation of streaks> 60 within 8 hours

due to insufficient 2

Plating time failed the sample
not be rated

no gas formation or formation of streaks> 60 within 72 hours

no gas formation or formation of streaks> 60 within 150 hours

') In Examples 8, 9 and 10 compositions were used in which the thiourea was omitted.

² ) Arbitrary scale determined by visual inspection, the number 1 being a matt, non-reflective surface and the number 5 being a glossy, mirror-like surface; the numbers between 1 and 5 represent degrees of reflectivity.

³ ) Determined by immersing the plated part in 6N hydrochloric acid at 38 ° C.

5 5 1 6th 25th 3 7th 50 4th 8th 0 9 25th 5 10 50 5

The table above shows that thiourea is an effective stabilizer however, that it does not improve the corrosion resistance or the gloss of the deposit and that it has an adverse effect on the deposit in the presence of copper (I) ions. In addition, copper (I) ions without thiourea improve gloss and corrosion resistance the deposit and the stability of the solution are considerable. As a result, those of sulfur are containing compounds of the type described above for free electroless alloy solutions preferred the purposes of the invention.

45 Examples 11 to 16

Copper (II) chloride was added in varying amounts to the composition of Example 1, and the obtained composition was used for plating chromium-plated steel. An 50 example no. the deposits thus obtained were then

peeled off the substrate, and each was on

analyzed their copper content. The amount of copper added to the solution and the amount of Copper found in the deposit on each plated substrate are reported in the table below.

The deposits of Examples 12-15 had a glossy appearance and no gas formation occurred or streaking was observed when the foils of the deposited alloys were placed in 6N hydrochloric acid at 38 ° C were immersed. The deposit of Example 16 was dull in appearance and color exhibited a powdery (granular) structure.

Examples 17-22

The procedure of Examples 11-16 was followed repeated, this time the copper (II) -chloric was replaced by copper (I) chloride. The results obtained are in the following table compiled.

Copper (II) content Copper content in the deposit in the solution

(ppm) (weight percent)

17 18 19 20

Example no.

Copper ffD content
in the solution

(ppm)

Copper content in the
deposit

(Weight percent)

21 60

100

200

0.01 0.39 0.76 1.40 1.90 3.90

20th

40

80

100

200

0.01
0.36
0.68
1.28
1.50
3.44 The results of Examples 11-22 are iiF i g. 2 of the drawing, in which the curve / 65 represents the curve for the copper (I) addition and curve I the curve for the copper (II) addition. It can be seen from this that the two curves are almost parallel to one another.

Example 23 Nickel sulfate hexahyurate 35g

Sodium hypophosphite monohydrate 15 g

Sodium acetate 15 g

Thiodiethylene glycol 25 ppm

Copper (I) chloride 100 ppm

Water ad 11

Temperature 91 to 96 ° C

pH about 5.0

The corrosion resistance of the deposits with varying thicknesses was as follows:

Salt Spray Test (ASTM B-17-57T)

Thickness on the steel

An electroless nickel-copper-phosphorus alloy was deposited from the above composition. She had a shiny appearance. No gas formation or streaking was observed when the foil of the alloy was immersed in 6N hydrochloric acid at 38 ° C. This indicates that certain types of sulfur compounds can be tolerated in the solution without adversely affecting the deposit, thereby improving the stability of the plating solution.

Example 24

Nickel sulfate hexahydrate 35 g

Hydroxyacetic acid

(70% solution) 30 g

Sodium hypophosphite monohydrate 15g

Sodium acetate 15g

Copper (I) chloride 75 ppm

Water ad 11

Temperature 93 ° C

pH about 5.0

A shiny, corrosion-resistant deposit was obtained from the above composition, containing about 3.0 weight percent co-deposited copper in a sample 0.254 mm thick. she had the following characteristics:

Specific weight .... about 8.20 g / cm ³

Melting point ( ⁰ C) about 1000

Vickers hardness (plated) 600

Maximum Vickers hardness through

Heat treatment 1100

Hydrogen content (ppm) 30 to 50

Magnetic properties ... not

magnetic *)

Specific resistance (micro

ohm cm) 150

Treatment time

0.0254 mm

0.0127 mm

0.0076 mm

0.0051 mm

at least 500 hours *)
at least 240 hours *)
at least 96 hours *)
at least 48 hours *)

*) Magnetic moment =

1000

of pure Ni.

") After the treatment with the 5% salt spray, no rust formation or discoloration could be found on the surfaces.

The provision of a new jewelry metal surface coating according to the invention represents a significant technical advance. At present, the most widely used jewelry metal surface coating is chromium which is electroplated onto a substrate. In a process for the deposition of chromium, be ^; For example, for the production of smooth layers, corrosion-resistant layers and when a non-conductor, for example plastic, is to be plated and for the production of a conductive layer, many steps are required. By using the electroless plating composition of the invention, a decorative metal surface coating can be made from the plating solution of the invention by electroless deposition alone, the deposition proceeding to full thickness.

Because of their unusual properties, the electroless nickel-copper-phosphorus alloy deposits usable for many new technical purposes. Although they have a mirror-like appearance their appearance can be changed for example by a quick plating of chrome Achieving a blue and white surface appearance characteristic of chrome plated Surfaces. The alloy deposit has also been found to lend itself to soldering, brazing,

Connecting by means of ultrasound and for the production of other metal-metal bonds according to known methods Procedure is suitable. Since the phosphorus content is consistently above 8 and preferably above 10% can be maintained, the deposited alloy has non-magnetic properties, making them suitable for a metal substrate for subsequent deposition of magnetic coatings is suitable. This is particularly urgent in view of the fact that the alloy has an unusually smooth surface, which results in an even distribution of the Magnetic coating material on the non-magnetic alloy base allows. Another desirable one Property is the hardness of the alloy, which is the same as a wear-resistant surface makes suitable. Finally, the alloy is characterized by a high degree of flexural ductility, dei It is surprising in view of the high phosphorus content, which so far has always been a brittle wedge led. Therefore, the alloy deposit can also be used in such uses in which there is movement of the alloy itself or the combination of the alloy with the substrate on which it is plated, occurs. In this respect

the alloy can be used alone without a substrate, for example to make metal fans will. The ductility is maintained even when the alloy is subjected to high temperatures in use exposed or up to about 100 minutes

is exposed to heat treatment at temperatures of up to 260 ° C for a long time. The ductility can be due to a low hydrogen content, which preferably does not exceed 100 ppm and usually varies between about 20 and 60 ppm.

For this purpose 3 sheets of drawings

Claims (6)

1 2 A wide variety of solutions for the electroless deposition of nickel coatings have already been proposed as patent claims: decorative coating layers, but these have generally emerged from the various 1. Aqueous solution for electroless storage - 5 different reasons than not for these purposes tion of a nickel-copper-phosphorus alloy has proven to be completely satisfactory. So own at most 25 percent by weight copper, containing, for example, those using such solutions Nickel ions, hypophosphite as a reducing agent, the nickel coatings applied do not provide the mirror teeth the nickel ions, a buffer for adjusting the luster, for decorative surface coatings the pH value and copper ions, which is what ίο is desirable, and also arise within indicates that they are practically free of short periods of yellowish haze on the surface Sulfur compound is the nickel plating brought into the solution, which is a corrosion product Sulphide and / or hydrosulphide ions supplies, and represent that under the action of air ent-copper (I) - and / or copper (II) ions. stands. That is, with the previously known water 2. Solution according to claim 1, characterized in that it is not possible to use nickel coatings draws that they apply 5 to 200 ppm copper (I) ions to a substrate, which is not only emen high contains. have a mirror-like gloss, but also a 3. Solution according to claim 1, characterized in that they have good corrosion resistance to show that they effectively protect the substrate from 15 to 100 ppm of copper (I) ions,
contains. ao That also applies to that in the US patent 4. Solution according to one of the preceding baths described in 27 62 723 for the currentless consultation, characterized in that it has a storage of a nickel coating, which in addition to nickel pH value between 4.0 and 13.0. ions, hypophosphite ions, and sulfide ions, which are known as 5. Solution according to claim 4, characterized by acting stabilizer, still contains copper ions. To indicates that they have a pH value between 4.0 »5 as specified in this patent specification in the and 5.5. known nickel plating baths sulfide ions in one 6. Solution after one of the preceding stabilizing amounts, d. H. in a lot of languages characterized in that they also contain greater than about 8 ppb (parts per billion) the one complexing agent for the nickel and / be. Since the sulfur it contains during the AbIa- or contains copper ions. If the nickel coatings also precipitate, one obtains when using this well-known nickel-plating bath a brittle, matt-looking and light-weight corrosive coating.