Externally electroless method for producing a nickel alloy and corresponding electrolyte

Abstract

The invention relates to a method for producing a nickel-phosphorus alloy in which a metallic substrate is dipped into an aqueous electrolyte containing at least nickel cations, hypophosphite ions, stabilisers and complexing agents, characterised in that the electrolyte additionally contains pyrones of formula I or the derivatives or salts thereof, wherein R1 represents a hydrogen atom or a hydroxyl group, R2 a methyl group, an ethyl group or a hydroxymethyl group, R3 a hydrogen atom or a hydroxyl group, and R4 a hydrogen atom, a hydroxyl group or a methyl ketone group, and to a corresponding electrolyte.

1 . A method for producing a nickel-phosphorus alloy wherein a metallic substrate is dipped into an aqueous electrolyte comprising nickel cations, hypophosphite ions, at least one stabiliser, and at least one complexing agent,
 and wherein the electrolyte further comprises a pyrone of formula I   
       
         
           
           
               
               
           
         
       
       or a derivative or salt thereof, wherein R1 is selected from the group consisting of a hydrogen atom and a hydroxyl group, R2 is selected from the group consisting of a methyl group, an ethyl group, and a hydroxymethyl group, R3 is selected from the group consisting of a hydrogen atom and a hydroxyl group, and R4 is selected from the group consisting of a hydrogen atom, a hydroxyl group, and a methyl ketone group. 
     
     
         2 . The method of  claim 1  wherein R1 is a hydroxyl group, R2 is an ethyl group, R3 is a hydrogen atom, and R4 is a hydrogen atom. 
     
     
         3 . The method of  claim 1  wherein the electrolyte further comprises at least one ascorbic acid compound selected from the group consisting of L-ascorbic acid and salts thereof, iso-ascorbic acid and salts thereof, and substances that produce L-ascorbic acid or iso-ascorbic acid in the electrolyte. 
     
     
         4 . The method of  claim 1  wherein the electrolyte comprises the at least one ascorbic acid compound in an amount between 0.5 g/L and 100 g/L. 
     
     
         5 . The method of  claim 1  wherein the electrolyte further comprises a mono-hydroxycarboxylic acid or a salt thereof. 
     
     
         6 . The method of  claim 1  wherein the compound of formula I is present in a concentration of at least 5 ppm. 
     
     
         7 . The method of  claim 1  wherein the compound of formula I is present in a concentration of between 0.1 g/l and 25 g/L. 
     
     
         8 . The method of  claim 1  wherein the method is carried out at an electrolyte temperature of at least 85° C. 
     
     
         9 . The method of  claim 7  wherein the method is carried out at an electrolyte temperature of at least 92° C. 
     
     
         10 . An aqueous electrolyte for producing nickel-phosphorus alloys comprising nickel cations, hypophosphite ions, at least one stabiliser, and at least one complexing agent,
 and further comprising a pyrone of formula I   
       
         
           
           
               
               
           
         
       
       or a derivative or salt thereof, wherein R1 is selected from the group consisting of a hydrogen atom and a hydroxyl group, R2 is selected from the group consisting of a methyl group, an ethyl group, and a hydroxymethyl group, R3 is selected from the group consisting of a hydrogen atom and a hydroxyl group, and R4 is selected from the group consisting of a hydrogen atom, a hydroxyl group, and a methyl ketone group. 
     
     
         11 . The aqueous electrolyte of  claim 10  wherein the electrolyte further comprises at least one ascorbic acid compound selected from the group consisting of L-ascorbic acid and salts thereof, iso-ascorbic acid and salts thereof, and substances that produce L-ascorbic acid or iso-ascorbic acid in the electrolyte. 
     
     
         12 . The aqueous electrolyte of  claim 11  wherein the electrolyte comprises the at least one ascorbic acid compound in an amount between 0.5 g/L and 100 g/L. 
     
     
         13 . The aqueous electrolyte of  claim 10  wherein the electrolyte further comprises a mono-hydroxycarboxylic acid or a salt thereof. 
     
     
         14 . The aqueous electrolyte of  claim 10  wherein the compound of formula I is present in a concentration of at least 5 ppm. 
     
     
         15 . The aqueous electrolyte of  claim 10  wherein the compound of formula I is present in a concentration of between 0.1 g/l and 25 g/L. 
     
     
         16 . The aqueous electrolyte of  claim 10  comprising a compound of formula I wherein R1 is a hydroxyl group, R2 is an ethyl group, R3 is a hydrogen atom, and R4 is a hydrogen atom.