Galvanic bath

Abstract

The invention relates to a galvanic bath for depositing a nickel-molybdenum alloy which consists of an aqueous solution of amine complexes and/or ammonium complexes in each case of nickel and/or molybdenum, the galvanic bath containing citric acid and/or citrate ions and/or oxidation products of the citric acid and/or the citrates, and molybdenum being present in different oxidation stages, in particular as Mo(V) and Mo(VI), in the galvanic bath.

1 . An electroplating bath for depositing a nickel-molybdenum alloy, said bath comprising an aqueous solution of amine complexes and/or ammonium complexes, in each case of nickel and/or molybdenum, wherein
 the electroplating bath contains a citric acid and/or citrate ions and/or oxidation products of citric acid and/or of citrates, and wherein molybdenum is present in different oxidation states, in the electroplating bath.   
     
     
         2 . The electroplating bath as claimed in  claim 1 , wherein the concentration of the citric acid and/or of the citrate ions and/or the oxidation products of citric acid and/or of citrates is in the range from 0.1 to 0.6 mol/l, in particular from 0.1 to 0.4 mol/l. 
     
     
         3 . The electroplating bath as claimed in  claim 1 , wherein the electroplating bath contains a proportion of molybdenum of at least 15% by weight. 
     
     
         4 . The electroplating bath as claimed in  claim 1 , wherein the concentration of nickel is in the range from 0.20 to 0.35 mol/l, in particular from 0.22 to 0.3 mol/l. 
     
     
         5 . The electroplating bath as claimed in  claim 1 , wherein the electroplating bath contains an ammonium concentration in the range from 0.20 mol/l to 0.40 mol/l, preferably from 0.25 to 0.35 mol/l. 
     
     
         6 . The electroplating bath as claimed in  claim 1 , wherein the concentration of molybdenum is in the range from 0.01 to 1 mol/l, in particular from 0.02 to 0.06 mol/l. 
     
     
         7 . The electroplating bath as claimed in  claim 1 , wherein the molybdenum/nickel ratio is in the range from 1:10 to 1:4. 
     
     
         8 . The electroplating bath as claimed in  claim 1 , wherein
 the electroplating bath contains further salts of alloy-forming metals, for example salts of nickel and/or cobalt and/or iron and/or phosphorus and/or rhenium and/or palladium and/or platinum, and   where the individual metals are preferably present in a concentration in the range from 0.1 to 5% by weight.   
     
     
         9 . The electroplating bath as claimed in  claim 1 , wherein the bath contains organic additives such as stabilizers, wetting agents and brighteners. 
     
     
         10 . The electroplating bath as claimed in  claim 1 , wherein the electroplating bath contains at least one additive selected from the following group or a mixture thereof:
 brighteners, preferably in a concentration in the range from 0.01 to 5% by weight,   wetting agents, preferably in a concentration in the range from 0.05 to 0.5% by weight,   electrolyte salts, preferably in a concentration in the range from 0.2 to 0.8 mol/l, particularly preferably in a concentration in the range from 0.3 to 0.6 mol/l,   sulfur-containing additives, preferably in the concentration range from 0.1 mg/l to 4.0 g/l, particularly preferably in the concentration range from 0.2 mg/1 to 2.0 g/l.   
     
     
         11 . The electroplating bath as claimed in  claim 1 , wherein electrolyte salts such as sodium salts and potassium salts are present in the electroplating bath. 
     
     
         12 . The electroplating bath as claimed in  claim 1 , wherein the concentration of the electrolyte salts is in the range from 0.2 to 0.8 mol/l, but preferably in the range from 0.3 to 0.6 mol/l. 
     
     
         13 . The electroplating bath as claimed in  claim 1 , wherein the electrolyte salt is an inorganic electrolyte salt, in particular from the group consisting of sulfates and chlorides, or an organic electrolyte salt, in particular from the group consisting of citrates. 
     
     
         14 . The electroplating bath as claimed in  claim 1 , wherein
 the electroplating bath contains ketoglutaric acid and/or aconitic acid and/or ketoglutarates and/or aconitates, and   where the concentration of these materials is preferably in the range from 0.1 to 0.6 mol/l, particularly preferably from 0.1 to 0.4 mol/l.   
     
     
         15 . The electroplating bath as claimed in  claim 1 , wherein the electroplating bath contains gluconates, tartrates or hydroxycarboxylic acids. 
     
     
         16 . The electroplating bath as claimed in  claim 1 , wherein
 sulfur-containing additives such as sulfanilamides, sulfonimides, sulfonic acids or sulfonates have been added to the electroplating bath, and   where the concentration of these sulfur-containing additives is preferably in the range from 0.1 mg/l to 4.0 g/l, in particular from 0.2 mg/l to 2.0 g/l.   
     
     
         17 . The electroplating bath as claimed in  claim 1 , wherein at least one surfactant from the group consisting of cationic, anionic, nonionic, amphoteric surfactants, or mixtures of the abovementioned surfactants, is present as wetting agent in the electroplating bath. 
     
     
         18 . The electroplating bath as claimed in  claim 1 , wherein the pH of the electroplating bath is in the range from 4 to 11, but particularly preferably in the range from 7.5 to 9.5. 
     
     
         19 . The electroplating bath as claimed in  claim 1 , wherein the electroplating bath contains alkali metal hydroxide for adjusting pH. 
     
     
         20 . The electroplating bath as claimed in  claim 1 , wherein the electroplating bath has a temperature in the range of from 20 to 85° C., in particular from 50° C. to 75° C. 
     
     
         21 . An object, preferably a contact element of a plug connector, the surface of which has been coated with a nickel-molybdenum alloy using an electroplating bath as claimed in  claim 1 . 
     
     
         22 . The electroplating bath as claimed in  claim 1 , wherein the molybdenum is present as Mo(V) and Mo(VI).