DE3202489C2 - Electrolyte for electrochemical gold plating and process for its production - Google Patents

Abstract

The invention relates to the field of the electrochemical deposition of metallic coatings, in particular it relates to an electrolyte for gold plating and a method for its production. The electrolyte for gold plating has the following composition (in g / l): hexapotassium μ-ethylenediaminetetraacetate bis (gold sulfite / I) 10.5-210, alkali salts of ethylenediaminetetraacetic acid 17.8-140, distilled water remainder. The electrolyte can also contain additives such as ethylenediamine tetra azetatokupfer / II-bis- (2-aminoethylammonium) or ethylenediaminetetraacetate-cadmium-bis- (2-aminoethylammonium) contain in an amount of 0.01 to 15 g / l. The process for producing the electrolyte for gold plating consists in the conversion of the reactants, the tetrachloro gold / III / acid, the alkali salt of ethylenediaminetetraacetic acid, alkali sulfite, potassium hydroxide and ammonium chloride in one stage in distilled water at a temperature of 80 up to 90 ° C and the following ratio of the reactants (in g / l) carried out: tetrachloro gold / III / acid 12.6-250, alkali salt of ethylenediaminetetraacetic acid 39-1000, alkali sulfite 6-190, potassium hydroxide 32-800, ammonium chloride 6.6 -132; this reaction results in an electrolyte for gold plating and a precipitate of chlorides and sulphates of alkali metals, and the latter is separated from the electrolyte by filtration. The present invention can be used in the electronics, watchmaking, and jewelry industries

Description

Tetrachloroauric [III] acid 12.6 to 250 Alkali salt of Ethylenediaminetetraacetic acid 39 to 1000 Alkali sulfite 6 to 190 Potassium hydroxide 32 to 800 Ammonium chloride 6.6 to 132

3 4

The additives mentioned in an amount below Hexakaliumys-ethylenediamine-

0.01 g / l does not affect the quality of the top coat; in tetraazetatobis (gold sulfite [I]) 210

in an amount above 15 g / l, however, they lead to sodium and potassium salts

an unnecessary hardness of the coating, whereby the inner ethylenediaminetetraacetic acid 52

The tension of the upper cover is increased, resulting in undistilled water remaining
is casual

The electrolyte according to the invention is produced according to a method which consists in that the. Ner environmental temperature of 3O ⁰ C using entry of the reactants - the Tetracljloro- barren by stainless steel or graphite. The gold [III] acid, the alkali salt of the ethylenediamine, current density 0.6 A / dm ² , the pH value 7.5-8.0.
traacetic acid, alkali sulfite, potassium hydroxide The current efficiency is 98%. The Vickers hardness and the ammonium chloride - in distilled water make 736-785 N / mm ² . The coating is matted in one stage at a temperature of 80 to 90 ⁰ G and dark yellow,
the following ratio of the named reactants (in
g / l): 15 Example 2

The implementation of tetrachloroauric [III] acid is carried out (12.6 g), disodium salt of ethylenediaminetetraacetic acid (39 g), potassium sulfite (9.5 g), potassium-20 hydroxide (32 g) and ammonium chloride (6.6 g) in 125 ml of distilled water at a temperature of 80 to 85 ° C through.

After the reaction has subsided, the solution becomes

carries out, through the said reaction an elec- tric cooled and left to stand until the precipitate of the trolyte for gold plating and a precipitate of the chlorides and sulfates of the alkali metals (the sodium ride and sulfates of the alkali metals and the last and potassium). The trolleys are then filtered to remove the electrolyte by filtration. Solution from the precipitate and pour distilled ethylenediaminetetreaacetate copper [II] -bis- (2-amino- water to fill up to 1 liter. As a result, ethylammonium) is made by reacting ethyl to obtain an electrolyte for gilding the following lenediaminetetraacetic acid with copper carbonate and 30 composition (in g / l):
Ethylenediamine and subsequent isolation from dimethylformamide. Hexapotassium - ^ - ethylenediamine-

Ethylenediamine tetraacetate cadmium bis (2-aminotetraacetate bis (gold sulfite [1]) 10.5

äthylammonium) is made by reacting ethyl, sodium and potassium salts

lenediaminetetraacetic acid with cadmium carbonate and ethylenediaminetetraacetic acid 17.8

Ethylenediamine and subsequent isolation from dirne- distilled water remainder

ethylformamide.

The electrolyte according to the invention for gold plating The electrochemical deposition is carried out with a

has a scattering power of up to 100% and a current ner temperature of 40 ⁰ C using an yield of 90 to 100%. The durability of the electrodes made of platinum or platinum-coated titanium. Current-. trolyts at a temperature of 25 ° C is more than dense D _k = 0.3 A / dm ² , pH = 8.0-3.5.
two years, the electrolyte starts to dissipate with a current. The current yield is 98%. The Vickers hardness

to decompose density of 15 A / dm ^2. The electrolyte is 883 N / mm ² . The coating is shiny yellow,
produces high-quality, highly finely dispersed coatings with a Vickers hardness of 687 45 _R. -, _
to 1961 N / mm ² , which μπι and more example ä at a thickness of 3
are pore-free.

The following are examples of specific feed- Man leads the implementation of tetrachloro-

compositions of the electrolyte according to the invention gold [III] acid (32.5 g), disodium salt of ethylenedi- and methods of making the same are listed. 50 amine tetraacetic acid (256.9 g), potassium sulfite (22.7 g), potassium hydroxide (216 g) and ammonium chloride (17.2 g) in Example 1 240 ml of distilled water at a temperature of

80 to 85 ° C.

The reaction of tetrachloro is carried out. After the reaction has subsided, the solution becomes

gold [lll] acid (250 g) disodium salt of the ethylenedi- 55 cooled and until the precipitation of the amine tetraacetic acid (785 g), potassium sulfite (190 g), potassium chlorides and sulfates of the alkali metals (of the sodium hydroxide (640 g) and ammonium chloride (132 g) in and potassium). Then the solution is filtered off 950 ml of distilled water from the precipitate in one stage with a solution and a distilled temperature of 90 ^° C. is poured through. Add water until it is filled to 1 liter. As a result

After the reaction has subsided, the solution 60 is obtained an electrolyte for gold plating of the following cooled down and until the precipitation of the composition (in g / l):
Chlorides and sulphates of alkali metals (sodium

and potassium). Then the Lö- Hexakotium-zü-ethylenediamine-

solution from the precipitate of the salts mentioned and tetraazetatobis (gold sulfite [I]) 27

Pour distilled water to make up to 1 liter of 65 sodium and potassium salts
added. The result is an electrolyte for ethylenediaminetetraacetic acid 19

gold plating with the following composition (in g / l): distilled water remainder

The electrochemical deposition is carried out at a temperature of 60 ^° C. using anodes made of platinum, graphite or stainless steel. Current density = 03 A / dm ² , pH = 8.0-9.0.

The current efficiency is 97%. The Vickers hardness of the coating is 902 N / mm ² . The coating is glossy light yellow.

Example 4

The implementation of tetrachloroauric [III] acid is carried out (105 g), ethylenediaminetetraacetic acid disodium salt (1000 g), chewing sulfite (95 g), potassium hydroxide (800 g) and ammonium chloride (66 g) in 750 ml of distilled water at a temperature of 80 to 85 ° C.

After the reaction has subsided, the solution is cooled and until the precipitate has precipitated out Let stand chlorides and sulfates of the alkali metals. The solution is then nitrated from the precipitate and pour distilled water to make up to 1 liter. The result is an electrolyte for Gold plating of the following composition (in g / l):

Example 6

The reaction of tetrachloroauric [IH] acid (12.6 g), ethylenediaminetetraacetic acid disodium salt (39 g), sodium sulfite (6 g), potassium hydroxide (32 g) and ammonium chloride (6.6 g) in 125 ml of distilled water is carried out at a temperature of 80 to 85 ° C.
After the reaction has subsided, the solution becomes

ίο cooled down and until there is no precipitation of the chlorides and sulphates of the alkali metals (of sodium and potassium). Then it is filtered remove the solution from the precipitate and pour distilled water until it is made up to 1 liter. in the The result is an electrolyte for gold plating with the following composition (in g / l):

Hexapotassium zi-ethylenediamine tetraacetate bis (gold sulfite [l])
Sodium and potassium salts of ethylenediaminetetraacetic acid, distilled water

10.5

17.8 remainder

Hexapotassium - ^ - ethylenediamine tetraacetate bis (gold sulfite [I])
Sodium and potassium salts of the
Ethylenediaminetetraacetic acid
distilled water

The electrochemical deposition is carried out at a temperature of 80 ° C using anodes made of platinum or platinum-coated titanium. Current density = 0.7 A / dm ² , pH = 9.0.

The current efficiency is 97%. The Vickers hardness of the coating is 883 N / mm ² . The coating is matt yellow.

Example 5

The reaction of tetrachloroauric [III] acid (32.5 g), the dipotassium salt of ethylenediaminetraacetic acid (437 g), potassium sulfite (22.7 g), potassium hydroxide (216 g) and ammonium chloride (17.2 g) in 240 ml distilled water at a temperature of 80 to 85 ⁰ C through.

After the reaction has subsided, the solution is cooled and until the precipitate has separated out Left to stand of potassium chloride and potassium sulfate, then the solution is filtered off from the precipitate and pour distilled water to make up to 1 liter. The result is an electrolyte for Gold plating of the following composition: (in g / l):

The electrochemical deposition is carried out at a temperature of 45 ° C using anodes made of platinum or platinum-coated titanium. Current density = 0.3 A / dm ² , pH = 8.0.

The current efficiency is 98%. The Vickers hardness of the coating is 883 N / mm ² . The coating is remainder 30 glossy yellow.

Example 7

To 1 liter of electrolyte, prepared according to Example 2, add 0.01 g of ethylenediaminetetraacetate cadmium bis (2-arninoethylammonium) added.

The result is an electrolyte for gold plating with the following composition (in g / l):

Hexapotassium - ^ - ethylenediamine-

tetraazetatobis (gold sulfite [I]) 10.5 sodium and potassium salts of

Ethylenediaminetetraacetic acid 17.8 Ethylenediaminetetraacetate cadmium

-bis- (2-aminoethylammonium) 0.01

distilled water remainder

Hexapotassium - ^ - ethylenediamine tetraacetate bis (goidsulfite [I])
Potassium salt of

Ethylenediaminetetraacetic acid
distilled water

55

27

32
rest

The electrochemical deposition is carried out at a temperature of 7O ⁰ C using anodes made of platinum, graphite or stainless steel. Current density = 0.4 A / dm ² , pH = 8.0-9.0. The current efficiency is 97%. The Vickers hardness of the coating is 912 N / mm ² . The coating is glossy light yellow.

60 The electrodeposition is carried out at a temperature of 85 ° C using platinum or stainless steel. Current density = 0.2 A / dm ² , pH = 8.5.

The current yield is 100%. The Vickers hardness of the coating is 981 N / mm ² . The coating is dense and shiny yellow.

Example 8

To 1 liter of electrolyte, prepared according to Example 1, 15 g of ethylenediaminetetraacetate cadmium bis (2-aminoethylammonium) are added added.

The result is an electrolyte for gold plating the following composition (in g / l):

Hexakaliunv / it-ethylenediamine tetraacetate bis (gold sulfite [l])
Sodium and potassium salts of ethylenediaminetetraacetic acid

210 52

Ethylenediamine tetraacetate cadmium bis (2-aminoethylammonium) distilled water

15 rest

The electrodeposition is carried out at a temperature of 40 ° C using anodes made of platinum, platinum-coated titanium or stainless steel. Current density = 0.8 A / dm ² , pH = 8.0.

The current yield is 100%. The Vickers hardness of the coating is 1961 N / mm ² . The coating is glossy yellow.

Example 9

To 1 liter of electrolyte, prepared according to Example 3, 1 g of ethylenediaminetetraacetate cadmium bis (2-aminoethylammonium) is added added.

As a result, an electrolyte for tracking can be obtained the following composition (in g / l):

Hexakotassiumyz-ethylenediamine tetraacetate bis (gold sulfite [I]) 27

Sodium and potassium salts of ethylenediaminetetraacetic acid 19

Ethylenediamine tetraacetate cadmium bis (2-aminoethy ammonium) 1

distilled water remainder

Hexakaliunv / rf-ethylenediamine tetraacetate bis (gold sulfite [l]) 105

Sodium and potassium salts of the
Ethylenediaminetetraacetic acid 140

Ethylenediamine tetraacetate copper I] -

-bis- (2-aminoethylammonium) 15

distilled water remainder

The electrochemical deposition is carried out at a temperature of 40 ° C. Use of anodes made of platinum, platinum-coated titanium or stainless steel. Current density = 0.8 A / dm ² , pH = 9.0.

The current yield is 100%. The Vickers hardness is 1765 N / mm ² . The coating is glossy yellow.

Example 12

Example 11

To 1 liter of electrolyte, prepared according to Example 4, is added 15 g of ethylenediaminetetraacetate copper / IIAbis- (2-aminoethylammonium) added. As a result, an electrolyte for gold plating with the following composition is obtained (in g / l):

To 1 liter of electrolyte, prepared according to Example 2,

add 0.01 g of ethylenediaminetetraacetate copper [II] bis- (2-aminoethylammonium) added. The result is an electrolyte for gold plating with the following composition (in g / l):

The electrochemical deposition is carried out at a temperature of 60 ⁰ C using anöden of platinum, platinized titanium or stainless steel. Current density = 0.4 A / dm ² , pH = 9.0.

The current yield is 100%. The Vickers hardness is 1373 N / mm ² . The coating is dense and shiny yellow.

Example 10 hexapotassium - ^ - ethylenediamine-

tetraacetate bis (gold sulfite [I]) 10.5

Sodium and potassium salts of the
Ethylenediaminetetraacetic acid 17.8

Ethylenediamine tetraacetate copper [II] - -bis- (2-aminoethylammonium) 0.01

distilled water remainder

The electrochemical deposition is carried out at a temperature of 80 ^° C. using anodes made of platinum, platinum-coated titanium or stainless steel. Current density = 0.2 A / dm ² , pH values = 9.0.

The current yield is 100%. The Vickers hardness is 981 N / mm ² . The coating is glossy yellow.

1.5 g of ethylenediaminetetraacetate copper [l l] bis (2-aminoethylammonium) added.

The result is an electrolyte for gold plating the following composition (in g / l):

Hexapotassium - ^ - ethylenediamine-

tetraacetatobis (gold sulfite [I]) 27

Sodium and potassium salts of ethylenediaminetetraacetic acid 19

Ethylenediamine tetraacetate copper [II] - -bis- (2-aminoethylammonium) 1,5

distilled water remainder

The electrochemical deposition is carried out at a temperature of 60 ^° C. using anodes made of platinum, platinum-coated titanium or stainless steel. Current density = 0.4 A / dm ² , pH = 8.5.

The current yield is 100%. The Vickers hardness of the coating is 1471 N / mm ² . The coating is shiny, rosy-yellow.

60

65

Claims (6)

1 2 From DE-OS 29 23 747 are an electrolyte of these claims: genus and a method for its production be known, the further still significant amounts of potassium 1. Electrolyte for electrochemical gold plating, containing sulfate and potassium hydrogen phosphate, the the 5 method consists in that one from the aqueous solution of tetrachloroid [HI] acid with ammonium hy- - Hexapotassium zi-ethylenediamine tetraacetate bis drug phosphate a poorly soluble gold compound, (gold sulfite / 1 /), namely bis- (dihydrophosphatomonohydrophospha- - Alkali salts of ethylenediaminetetraacetic acid to) ammonium aurate precipitates, the precipitate of the and washes 10 chloride ions and then this precipitate - Contains distilled water by introducing it into an aqueous solution of Disodium salt of ethylenediaminetetraacetic acid, potassium characterized.daßer umhydroxid and potassium sulfite dissolves This process is multi-stage and this leads to irreplaceable mechanical 10.5 to 210 g / l hexapotassium - ^ - ethylenediamine - 15 see gold losses. In addition, one receives after tetraazetatobis (gold sulfite [rD this process uses an electrolyte that 17.8 to 140 g / l alkali salts containing ethylenediaminetetra- phate and potassium sulphate. When setting acetic acid of the electrolytic bath with an electrolyte 20 substances enriched what the technological process contains the gold plating adversely affected. It is also not 2. Electrolyte according to claim 1, characterized thereby possible, the content of the electrolyte of hexapotassium - / «- draws that he also increase ethylenediaminetetraazeta-ÄthylendiamintetraacetatobisigoldsulfitTJ]) tokupfer [ll] - bis (2-aminoethylammonium) in one and the presence of admixtures, such as potassium hy amount from 0.01 to 15 g / l contains 25 drug phosphate and potassium sulphate limits the consumption 3. Electrolyte according to claim 1, characterized in the area of application of this electrolyte. draws that he is also Äthylendiamintetraazeta- The invention is based on the object tocadmium-bis- (2- (aminoethylammonium) in an electrolyte for electrochemical gold plating from 0.01 to 15 g / l, wrap that does not contain any additions of potassium 4. Process for the preparation of the electrolyte contains 30 gene phosphate and potassium sulfate and one size according to Claim 1, characterized in that the in Ren content of hexapotassium-Zi-ethylenediaminetetraaceto distilled Dissolved water, hereinafter referred to as gtobis (gold sulfite [I]), as well as one mentioned in the technology Reactants in one stage with a design see a simpler process for the production temperature from 80 to 90 ° C and the following ratio of the electrolyte to the electrochemical gold plating nis of reactants (g / l): 35 to develop, which makes it possible to develop irreplaceable mechanical Gold losses can practically be ruled out completely. This is achieved by the features listed in the characterizing part of claims 1 and 4. Beneficial Further developments of the electrolytes according to claim 1 are 40 in claims 2 and 3, further developments of the Method according to claim 4 are given in claims 5 and 6. If the electrolyte contains hexapotassium / i! - be implemented, whereby by this conversion Äthylendiamintetraacetatobis (gold sulfite [I]) of less an electrolyte for gold plating and a precipitate 45 as 10.5 g / l is the speed of the electrochemider Chlorides and the sulphates of the alkali metals get deposition unsatisfactory and with a geten and the precipitate of the electrolyte holds hexapotassium - ^ - ethylenediamine tetraacetal by Filtration is separated. bis (gold sulfite [I]) of more than 210 g / l deteriorates 5. The method according to claim 4, characterized in the quality of the coating. draws that the electrolyte after filtration 50 The content of the electrolyte of alkali salt of the ethylene Ethylenediamine tetraacetate copper [II] -bis- (2-amino diamine tetraacetic acid depends on the content of the elec- äthylammonium) in an amount of 0.01 to 15 g / l trolyts of hexapotassium - ^ - Äthylendiamintetraacetato- is admitted. bis (gold sulfite [I]) immediately. 6. The method according to claim 4, characterized in that the electrolyte according to the invention does not contain any marking, that the electrolyte after filtration 55 amounts in the form of phosphates and sulfates of the Ethylenediamine tetraacetate cadmium bis (2-amino alkali metals, it contains hexakali and n-ethylenediamine ethylammonium) added in an amount of 0.01 to 15 g / l of tetraacetate bis (gold sulfite [I]) at a high concentration will. tion, which makes it possible to comprehensively turn around. 60 The accumulation of the alkali salt of ethylenediamine intetraacetic acid in the electrolytic bath does not affect the technological process of gold plating. To increase the current yield and the hardness of the The invention relates to an electrolyte for coating, it is recommended to use an electrolyte for electrochemical gelling Gold plating, the hexapotassium - // - 65 dung to use, the further ethylenedianiintetraaccäthylcndiamintetraazetatobis (gold sulfite [I]), Alkali salts tatokupfer [II] -bis- (2-aminoäthy! Ammoniuin) or Äihyders Ethylenediaminetetraacetic acid and distilled waslenediaminetetraacetate cadmium bis (2-aminoethylainser contains, and a process for its production. monium) in an amount of 0.01 to 15 g / l. Tetrachloroauric [III] acid 12.6 to 250 Alkali salts of Ethylenediaminetetraacetic acid 39 to 1000 Alkali sulfite 6 to 190 Potassium hydroxide 32 to 800 Ammonium chloride 6.6 to 132